Re: [time-nuts] Temp/Humidity control systems?

[Wes]

On 10/30/2016 10:18 PM, Bill Hawkins wrote:

Think of the fun you'll have determining the heat flow model constants
for the system. In particular, there's no air flow sensor because they
are expensive. You'll need to determine the relation between fan speed
and air flow.
You can buy an automotive mass airflow sensor on eBay for a few dollars.  The 
flow rates may or may not be appropriate, but they're out there.

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Re: [time-nuts] Temp/Humidity control systems?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 31 October 2016 at 10:37, Poul-Henning Kamp  wrote:

> 
> In message  gmail.com>, "Dr. David K
> irkby (Kirkby Microwave Ltd)" writes:
>
> >> > [...] so it might be a relatively cheap way to measure humidity.
> >>
> >> 80m wave-guide is neither cheap, nor in most circumstances, practical
> :-)
> >
> >But you don't need 80 m of waveguide. 100 mm or so would be sufficient.
>
> Then it would require a quite high frequency...
>

If you try to do an attenuation measurement in the normal operating
wavelength of the guide, then I agree you would need a huge length unless
at very high frequency (100 GHz+), where water absorption becomes high  But
that's not the approach I would take.

I would look at trying to exploit the variation of cutoff frequency of
waveguide with humidity. WR90, which has an internal width of 0.900"
(that's where the 90 comes from),  has a cutoff frequency around 6.5 GHz. I
would expect that to be pretty dependent on the permittivity in the guide.
6.5 GHz is not a ridiculously high frequency to generate, and WR90 is not
unmanageably large. Making the guide bigger would reduce the frequency you
need to generate.

. .
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Re: [time-nuts] Temp/Humidity control systems?

[Bob Camp]

Hi

A multi mode resonant cavity is probably the “easy” approach. Like the 
waveguide, it is 
pressure / temperature / humidity sensitive. The same “can I separate the 
effects” issue applies.

Any enclosed device will have issues with properly representing the humidity in 
the room. 
It’s fortunate that the control goal is 50%+/- 30%. Fancy monitors are not 
required ...

Bob

> On Oct 31, 2016, at 6:17 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 31 Oct 2016 06:07, "Poul-Henning Kamp"  wrote:
>> 
>> 
>> In message <
> canx10hcpa5sozukqe00c5hcm-zrwkblnsojcoljokdriols...@mail.gmail.com>, "Dr.
> David K
>> irkby (Kirkby Microwave Ltd)" writes:
>> 
>>> [...] so it might be a relatively cheap way to measure humidity.
>> 
>> 80m wave-guide is neither cheap, nor in most circumstances, practical :-)
> 
> But you don't need 80 m of waveguide. 100 mm or so would be sufficient.
> 
> I have not looked at any of the papers someone have a link to, but I would
> imagine one problem would be there's litter airflow in the waveguide,  so
> it would be very slow to respond.
> 
> Dave
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message 
, "Dr. 
David K
irkby (Kirkby Microwave Ltd)" writes:

>> > [...] so it might be a relatively cheap way to measure humidity.
>>
>> 80m wave-guide is neither cheap, nor in most circumstances, practical :-)
>
>But you don't need 80 m of waveguide. 100 mm or so would be sufficient.

Then it would require a quite high frequency...

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Temp/Humidity control systems?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 31 Oct 2016 06:07, "Poul-Henning Kamp"  wrote:
>
> 
> In message <
canx10hcpa5sozukqe00c5hcm-zrwkblnsojcoljokdriols...@mail.gmail.com>, "Dr.
David K
> irkby (Kirkby Microwave Ltd)" writes:
>
> > [...] so it might be a relatively cheap way to measure humidity.
>
> 80m wave-guide is neither cheap, nor in most circumstances, practical :-)

But you don't need 80 m of waveguide. 100 mm or so would be sufficient.

I have not looked at any of the papers someone have a link to, but I would
imagine one problem would be there's litter airflow in the waveguide,  so
it would be very slow to respond.

Dave
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Re: [time-nuts] Temp/Humidity control systems?

[Jeremy Nichols]

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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message 
, "Dr. 
David K
irkby (Kirkby Microwave Ltd)" writes:


> [...] so it might be a relatively cheap way to measure humidity.

80m wave-guide is neither cheap, nor in most circumstances, practical :-)


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[Bill Hawkins]

Looking at it as a problem in thermodynamics, which has equations for
the flow and storage of heat, it might have a simple solution.

If you can have your equipment closet hotter than the basement will ever
be, we can use basement air for cooling the closet.
The basement air can be held to about +/- 5 degrees F with conventional
heating and cooling. You should dehumidify to 50% or less if that is a
problem. 30% is a reasonable minimum. You should have a fan or two to
stir the basement air.

Install the biggest standard air filter you can find in an inside wall
of the closet, which will filter incoming air. Install one or more
exhaust fans on the wall opposite the filter. At least one of the fans
must be variable speed. Or you could use an array of small fans with
individual switches to get controlled air flow - better yet, make two of
the fans in the array variable speed. Shouldn't be a problem if you use
common 12 VDC fans.

Now for the control system. You need sensors for closet temp and
basement temp and humidity, and also one for the power flow into the
closet. Electrical power leaving the closet on 50 ohm cables is assumed
to be negligible. You need a D/A converter to control the speed of the
fans.

You know the temperature of the closet air (maybe want an average) and
you know the temp and RH of air available to cool the closet. The RH
will affect the heat capacity of the air. Now you calculate the amount
of basement air needed to balance the heat flows at the desired
temperature, and adjust the fans to provide it.

Think of the fun you'll have determining the heat flow model constants
for the system. In particular, there's no air flow sensor because they
are expensive. You'll need to determine the relation between fan speed
and air flow.

I'd do this myself to determine the attainable precision, but I live in
an old folks apartment now. Let us know how it turns out.

Bill Hawkins

I know you wanted a COTS solution, but I think this is what you need for
1 degree control. You can't do it with on/off control.

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Re: [time-nuts] Temp/Humidity control systems?

[Wes]

On 10/27/2016 6:43 AM, Ron Bean wrote:

BTW some of us are more sensitive to humidity than others. I can't tell
you the RH of a room, but I can tell you when it's too dry for comfort.
I want it as close to 50% as I can get it without growing mold on the
walls. Some "experts" claim that 30% is good enough for anyone, but
they're wrong.

Clearly, you don't live in Arizona :-)
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Re: [time-nuts] Temp/Humidity control systems?

[Attila Kinali]

On Sun, 30 Oct 2016 20:38:49 +
"Dr. David Kirkby (Kirkby Microwave Ltd)"  
wrote:

> I was just reading the Keysight forum on VNAs. Someone was having issues
> measuring a bit of waveguide 80 m long. Dr. Joel Dunsmore pointed out that
> humidity has an effect in waveguide.
> 
> I'm guessing this is due to the change in permittivity in the air, which
> would be most noticeable near the cutoff frequency of the waveguide. That
> should change the magnitude of the reflection, not just the phase, so it
> might be a relatively cheap way to measure humidity.
> 
> Just thinking aloud. I'm probably talking rubbish.

This has been used for quite some time. Though cheap is relative :-)
A non-representative selection of papers that I have lying around here:

"A Reference Standard for Measuring Humidity of Air Using a Re-entrant Radio
Frequency Resonator", by Huang, Ripple, Moldover, Scace, 2006
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=902995

"Automatic digital microwave hygrometer", by Hasegawa, Stokesberry, 1975
http://dx.doi.org/10.1063/1.1134331

"ELECTRICAL PROPERTIES OF ATMOSPHERIC MOIST AIR: A SYSTEMATIC,
 EXPERIMENTAL STUDY", by Carlon, 1988
http://www.dtic.mil/dtic/tr/fulltext/u2/a199599.pdf

"The Refractive Indices and Dielectric Constants of Air and its Principal
Constituents at 24,000Mc/s", by Essen, Froome, 1951
http://dx.doi.org/10.1088/0370-1301/64/10/303

Don't ask why i have these papers


Attila Kinali





-- 
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Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Temp/Humidity control systems?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 28 October 2016 at 01:05, Poul-Henning Kamp  wrote:

>The exception is the "cold mirror" type of sensor, which measures the
> >dewpoint by cooling a mirror and bouncing a light off it to sense the
> >temperature where dew condenses on it. Those are expensive, and they
> >require maintenance to keep the mirror clean.
>
> And they are comparatively slow, last I saw one it could only do
> a measurement every second minute.
>

I was just reading the Keysight forum on VNAs. Someone was having issues
measuring a bit of waveguide 80 m long. Dr. Joel Dunsmore pointed out that
humidity has an effect in waveguide.

I'm guessing this is due to the change in permittivity in the air, which
would be most noticeable near the cutoff frequency of the waveguide. That
should change the magnitude of the reflection, not just the phase, so it
might be a relatively cheap way to measure humidity.

Just thinking aloud. I'm probably talking rubbish.

Dave
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message 
, Chris 
Albert
son writes:

>[...] the water comping out of the pipe is always about 58F.

Unless you live close to a volcano or an artesian spring, the
temperature will be exactly the yearly average air-temperature of
your climate.

Precisely how deep you need to dig for stability that varies with
your geology and precipitation, it may be as little as one meter,
it may be as deep as 10 meters.

>My point here is that if you really want to keep something at constant
>temperature what you want is huge amounts of dirt, rock or concrete, not so
>much a heater/cooler

This is certainly true for any passive object, but as soon as we talk
about heat-emitting objects, this no longer holds, and you have to
take thermal conductivity, -capacity and -impendance into account.

If you happen to dig a deep trench anyway, by all means plonk a
PE40 tube down there to run liquid through, but unless you are
*really* dedicated, don't start digging just for constant
temperature.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[Chris Albertson]

There are people making a lot of money installing heating cooling systems
that take advantage of the Earth's thermal stability.   What they do is dig
a hole the size of a swimming pool and lay out a zig-zag pattern of pipe on
the bottom of the hole then backfill the hole.   Assuming the pipe is
buried deep enough which depends on where you live, the water comping out
of the pip is always about 58F.   In the summer they use the 58F water to
cool the air, in the winter with snow outside 58F water seems almost warm
and ty use it for heating, pre-heating.If the pipe farm is big enough
you can keep a house comfortable with just a water recirculation pump.

My point here is that if you really want to keep something at constant
temperature what you want is huge amounts of dirt, rock or concrete, not so
much a heater/cooler

A basement is not quite deep enough nor far enough away from heated living
space to be stable.  But I think rather then fighting it, measure the
day/night year round average temperate of the basement room and make THAT
your set point temperature.This minimizes the temperature difference
and minimizes the amount of work out heater/cooler will have to do.It
should save money but also reduce the amount of temperature change. So,
 try using bricks or blocks all around and set the thermostat for about 58F
or whatever the local average is

For something as small as a 10Mhz oscillator I've wanted to try an
experiment where I drill hole drop in the electronic part then fill in the
hole.



On Thu, Oct 27, 2016 at 12:41 AM, Poul-Henning Kamp 
wrote:

> 
> In message <20161026210517.26c0fd397b1cae5ba9c12...@kinali.ch>, Attila
> Kinali w
> rites:
>
> >Probably the easiest is to get some glass/mineral wool insulation and
> >put it over all the walls, including ceiling and floor. I do not recommend
> >any foam or styropor based insulation as almost all of them are
> inflamable.
> >This should get you into the area of 10-100W/K thermal resistance for your
> >closet (assuming something like 4cm thick insulation gets about 40W/K).
>
> Stop!
>
> Over insulating is a 100% sure-fire way to get unstable temperature inside,
> because it amplifies the consequences of any change in power dissipation.
>
> It is a classic mistake to build a 100mm insulated enclosure inside an
> office-like enviroment and end up having less stable temperature on
> the inside than the outside.
>
> Cinderblocks is a much better material for that scenario, because they
> have both thermal mass and inertia (= heat capacity and heat impedance)
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Temp/Humidity control systems

[Van Horn, David]

There is a wax which melts at 70F.  Phase change stores and releases a lot of 
heat.

Somewhat optimistic IMHO
https://www.wired.com/2015/05/table-sucks-heat-lower-ac-bills/

http://www.stacoolvest.com/news/

Technical:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4809117/
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Re: [time-nuts] Temp/Humidity control systems?

[Joe Leikhim]

I am in Florida and my garage gets quite warm and damp. I installed a 
window A/C unit and the results were mixed. It got cooler, but not 
necessarily dryer. And my utility bill suffered. So I built up a simple 
controller to control the 120VAC power to the A/C. It is a thermoplastic 
plastic electrical box containing a humidistat, a relay , low voltage 
transformer (doorbell type) and a mechanical timer.


I set the humidistat to ~ 55% where above that setting the relay turns 
on the A/C load. A mechanical timer allows me to force the A/C to run up 
to an hour if I am working in the garage and need cooling. The A/C is 
set to minimum temperature so it continues to control humidity even if 
the temperature is low. I have a provision to wire a magnetic reed 
switch to the garage door to turn off the A/C if the garage door is 
opened. I still need to run a wire and hook that up.


I am also remodeling an existing storage "shed" attached on the side of 
my house into a walk in closet and intend to replicate this same 
arrangement with a small wall mounted A/C to keep that space dry.


--
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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Re: [time-nuts] Temp/Humidity control systems?

[F. W. Bray]

Have you looked into wine cellar equipment?

They sell equipment that's designed to control temperature and humidity for 
custom built wine cellars that can be anything from an retrofitted insulated 
closet to a small room.  I think that they also sell prefab cellars to put into 
an existing space.

KE6CD

> On Oct 26, 2016, at 8:59 AM, John Ackermann N8UR  wrote:
> 
> I may have the opportunity to build a small "clock room" and am considering 
> whether I could make it an environmentally controlled space.  I'd like to 
> learn about the options for doing this.
> 
> The space would probably be 6x8 feet or so, in a basement with one outside 
> wall.
> 
> Can anyone point me to purveyors of the hardware to do something like this?  
> Because I'll have a limited time to build this, I'm looking for something 
> that uses more-or-less off the shelf gear, and not a whole lot of custom 
> engineering.
> 
> Thanks!
> John
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Re: [time-nuts] Temp/Humidity control systems?

[David]

Years ago I had to deal with this and the instruments and sensors we
used matched well against dry and wet bulb measurements.  I suspect
consumer level stuff varies considerably in reliability and accuracy.

The capacitive sensors are tricky to use because they require AC
excitation to prevent damage from electromigration.  I see a lot of
integrated sensors are available now and I wonder how well they really
work

On Fri, 28 Oct 2016 09:39:04 +1100, you wrote:

>You are correct to question commercial humidity sensors.
>It seems to have come about because no-one can make a dollar by selling 
>humidity.
>Manufacturers do not tell the truth, they think ours is as good as theirs so 
>we 
>should claim the same accuracy. People buy these sensors, believe them, and 
>buy more.
>
>It is not hard to measure humidity/temperature. (they should be measured 
>together).
>Cover the bulb of an ASTM32C thermometer with cotton gauze. Insert it through 
>the wall
> of a short length (18”) of 4” metal tube, insert another ASTM32C thermometer 
> through the side 
>of the tube 4” upstream. Put a computer fan on the outlet of the tube sucking 
>air over 
>the thermometer bulbs at about 4m/s. Wet the thermometer bulb, but NEVER touch 
>it with your fingers.
>In about 3 minutes you can take two temperature readings. There are a number 
>of tables and calculation methods,
>some much worse that others that will convert these values to air temperature, 
>Relative humidity,
>Dew Point temperature etc. You get accuracy of 1% from temperatures measured 
>to 0.1C.
>If anyone is interested I have basic routines for XCEL spreadsheet use to do 
>the hard work.
>This is based on the WMO Reference Psychrometer developed by Russel Wylie of 
>NML Australia.
>
>> On 28 Oct 2016, at 12:43 AM, Ron Bean  wrote:
>> 
>> And since this is time-nuts: Measuring humidity accurately is tricky. 
>> According to people who have tested them, commercial electronic humidity 
>> sensors, when tested in a lab, have never come anywhere close to the 
>> accuracy claimed in the data sheet. The best you can hope for is 
>> consistent readings, not absolute accuracy.
>> 
>> ...
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

Dew Point measurement technology is limited by surface energy problems,
in the near vicinity of the surface,Van der Waals or London forces create 
uncertainties
in the physical processes and dew point instruments always seem to have these 
uncertainties.
The physical equilibrium on the surface of a water film has proved reliable, 
hence the reliance 
of reference instruments using psychrometery. Dew point technology is mainly 
used for measurement
at extremes of dewpoint well outside the conditions in ambient weather and in 
in-line situations 
in industrial control where precision gives way to convenience.

cheers,
Neville Michie

> On 28 Oct 2016, at 11:05 AM, Poul-Henning Kamp  wrote:
> 
> 
> In message <20161027134312.ga18...@panix.com>, Ron Bean writes:
> 
>> And since this is time-nuts: Measuring humidity accurately is tricky. 
>> According to people who have tested them, commercial electronic humidity 
>> sensors, when tested in a lab, have never come anywhere close to the 
>> accuracy claimed in the data sheet.
> 
> The main problem in measuring humidity is physical gradients:  It is
> incredibly hard to create a volume of homogenous humidity on a planet
> which has gravity, and for that reason, a lot of labs are not anywhere
> near as accurate as they think they are.
> 
>> The exception is the "cold mirror" type of sensor, which measures the 
>> dewpoint by cooling a mirror and bouncing a light off it to sense the 
>> temperature where dew condenses on it. Those are expensive, and they 
>> require maintenance to keep the mirror clean.
> 
> And they are comparatively slow, last I saw one it could only do
> a measurement every second minute.
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <20161027134312.ga18...@panix.com>, Ron Bean writes:

>And since this is time-nuts: Measuring humidity accurately is tricky. 
>According to people who have tested them, commercial electronic humidity 
>sensors, when tested in a lab, have never come anywhere close to the 
>accuracy claimed in the data sheet.

The main problem in measuring humidity is physical gradients:  It is
incredibly hard to create a volume of homogenous humidity on a planet
which has gravity, and for that reason, a lot of labs are not anywhere
near as accurate as they think they are.

>The exception is the "cold mirror" type of sensor, which measures the 
>dewpoint by cooling a mirror and bouncing a light off it to sense the 
>temperature where dew condenses on it. Those are expensive, and they 
>require maintenance to keep the mirror clean.

And they are comparatively slow, last I saw one it could only do
a measurement every second minute.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[Eric Scace]

   Ha!

   That is the system my brother Greg Scace designed and built while at NIST. 
He has given a lot of papers around the world on its metrology technology.

   On the side, he manufactures the reference calibration tools for espresso 
machines 
.

   Greg is still working there… as is his wife Casey (on cryptography)… and my 
father Bob Scace worked there for 25 years on microelectronics and 
nanotechnology… my other brother Brian retired recently from NIST… and I worked 
there for a few years 1978-1981 on international data networking problems. I 
think the Scace family has the record for maximum number of family members 
employed at NIST.

— Eric Scace

> On 2016 Oct 27, at 13:32 , William H. Fite  wrote:
> 
> Just for the fun of it, here is how NIST measures humidity.
> https://www.nist.gov/sites/default/files/documents/calibrations/sp250-83.pdf
> 

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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

You are correct to question commercial humidity sensors.
It seems to have come about because no-one can make a dollar by selling 
humidity.
Manufacturers do not tell the truth, they think ours is as good as theirs so we 
should claim the same accuracy. People buy these sensors, believe them, and buy 
more.

It is not hard to measure humidity/temperature. (they should be measured 
together).
Cover the bulb of an ASTM32C thermometer with cotton gauze. Insert it through 
the wall
 of a short length (18”) of 4” metal tube, insert another ASTM32C thermometer 
through the side 
of the tube 4” upstream. Put a computer fan on the outlet of the tube sucking 
air over 
the thermometer bulbs at about 4m/s. Wet the thermometer bulb, but NEVER touch 
it with your fingers.
In about 3 minutes you can take two temperature readings. There are a number of 
tables and calculation methods,
some much worse that others that will convert these values to air temperature, 
Relative humidity,
Dew Point temperature etc. You get accuracy of 1% from temperatures measured to 
0.1C.
If anyone is interested I have basic routines for XCEL spreadsheet use to do 
the hard work.
This is based on the WMO Reference Psychrometer developed by Russel Wylie of 
NML Australia.

> On 28 Oct 2016, at 12:43 AM, Ron Bean  wrote:
> 
>> * You cannot "feel" absolute humidity, always measure it.
> 
> And since this is time-nuts: Measuring humidity accurately is tricky. 
> According to people who have tested them, commercial electronic humidity 
> sensors, when tested in a lab, have never come anywhere close to the 
> accuracy claimed in the data sheet. The best you can hope for is 
> consistent readings, not absolute accuracy.
> 
> The exception is the "cold mirror" type of sensor, which measures the 
> dewpoint by cooling a mirror and bouncing a light off it to sense the 
> temperature where dew condenses on it. Those are expensive, and they 
> require maintenance to keep the mirror clean.
> 
> BTW some of us are more sensitive to humidity than others. I can't tell 
> you the RH of a room, but I can tell you when it's too dry for comfort. 
> I want it as close to 50% as I can get it without growing mold on the 
> walls. Some "experts" claim that 30% is good enough for anyone, but 
> they're wrong.
> 
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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

Just for the fun of it, here is how NIST measures humidity.
https://www.nist.gov/sites/default/files/documents/calibrations/sp250-83.pdf

On Thu, Oct 27, 2016 at 3:30 PM, William H. Fite  wrote:

> NIST-traceable hygrometers are readily available in the $200-$400 range.
>
> Or you can get a couple of airtight boxes of precisely the same volume and
> go gravimetric...
>
> On Thu, Oct 27, 2016 at 9:43 AM, Ron Bean 
> wrote:
>
>> >* You cannot "feel" absolute humidity, always measure it.
>>
>> And since this is time-nuts: Measuring humidity accurately is tricky.
>> According to people who have tested them, commercial electronic humidity
>> sensors, when tested in a lab, have never come anywhere close to the
>> accuracy claimed in the data sheet. The best you can hope for is
>> consistent readings, not absolute accuracy.
>>
>> The exception is the "cold mirror" type of sensor, which measures the
>> dewpoint by cooling a mirror and bouncing a light off it to sense the
>> temperature where dew condenses on it. Those are expensive, and they
>> require maintenance to keep the mirror clean.
>>
>> BTW some of us are more sensitive to humidity than others. I can't tell
>> you the RH of a room, but I can tell you when it's too dry for comfort.
>> I want it as close to 50% as I can get it without growing mold on the
>> walls. Some "experts" claim that 30% is good enough for anyone, but
>> they're wrong.
>>
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>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
>
> --
> Intelligence has never been proof against stupidity.
>



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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

NIST-traceable hygrometers are readily available in the $200-$400 range.

Or you can get a couple of airtight boxes of precisely the same volume and
go gravimetric...

On Thu, Oct 27, 2016 at 9:43 AM, Ron Bean 
wrote:

> >* You cannot "feel" absolute humidity, always measure it.
>
> And since this is time-nuts: Measuring humidity accurately is tricky.
> According to people who have tested them, commercial electronic humidity
> sensors, when tested in a lab, have never come anywhere close to the
> accuracy claimed in the data sheet. The best you can hope for is
> consistent readings, not absolute accuracy.
>
> The exception is the "cold mirror" type of sensor, which measures the
> dewpoint by cooling a mirror and bouncing a light off it to sense the
> temperature where dew condenses on it. Those are expensive, and they
> require maintenance to keep the mirror clean.
>
> BTW some of us are more sensitive to humidity than others. I can't tell
> you the RH of a room, but I can tell you when it's too dry for comfort.
> I want it as close to 50% as I can get it without growing mold on the
> walls. Some "experts" claim that 30% is good enough for anyone, but
> they're wrong.
>
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> mailman/listinfo/time-nuts
> and follow the instructions there.
>



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Re: [time-nuts] Temp/Humidity control systems?

[Ron Bean]

>* You cannot "feel" absolute humidity, always measure it.

And since this is time-nuts: Measuring humidity accurately is tricky. 
According to people who have tested them, commercial electronic humidity 
sensors, when tested in a lab, have never come anywhere close to the 
accuracy claimed in the data sheet. The best you can hope for is 
consistent readings, not absolute accuracy.

The exception is the "cold mirror" type of sensor, which measures the 
dewpoint by cooling a mirror and bouncing a light off it to sense the 
temperature where dew condenses on it. Those are expensive, and they 
require maintenance to keep the mirror clean.

BTW some of us are more sensitive to humidity than others. I can't tell 
you the RH of a room, but I can tell you when it's too dry for comfort. 
I want it as close to 50% as I can get it without growing mold on the 
walls. Some "experts" claim that 30% is good enough for anyone, but 
they're wrong.

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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 8:06 AM, Poul-Henning Kamp wrote:


In message <837330db-2015-4ae5-8c9c-f444f569f...@n1k.org>, Bob Camp writes:


Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” (let’s
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably
ok for any gear that I can think of. As long as you *never* go in and out of the
cave, comfort in the cave is a non-issue.


Danger Will Robinson!

Under no circumstances should your dewpoint be above the temperature on
the other side of the door.

If you have 40C at 80% humidity your dew-point temperature is 35C, which means
that whenever you open the door your clock cave will fog up.

If you run your clock cave at 40C, humidity needs to be well below
30% to hold the dewpoint below room tempreatyre.  That is both hard,
expensive and prone to electrostatic discharges.


Assuming the humidity in the basement is under control (if not, fix that), all 
I need
to do for humidity in the closet is to exchange air with the basement.


"fix that" is usually non-trivial, and from very to horribly expensive.

The cardinal rule is that you should only exchange air (basement/outside,
or cave/basement) when the air outside has lower *ABSOLUTE* humidity.

And I keep stressing that it is *ABSOLUTE* humidity, because people simply
don't pay it enough attention.

25C/40%RH air holds 9.2 g/m³ water ... as does 15C/72%RH air.

This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.

One would think that somebody had designed fans to measure this,
but it is expensive: Cheap humidity sensors measure relative humidity
and you need to correct for both temperature and pressure to get
absolute humidity.



And having looked into this in some detail - there's a whole lot of "go 
look at a psychometric chart" when you try and write some code to do the 
conversion.


It's similar to the "steam tables" (in fact, it's identical to the 
problem of generating steam tables, it's all about vapor pressure of 
water vs temperature and such)
There's not some nice equation to solve - It's more done by an iterative 
solution of the equation that goes the other way.



https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4813973/pdf/sensors-16-00398.pdf
has some of the background




And therefore, at the risk of repeating myself again:

If you build your clock cave in the basement, it should be air-tight
and you should manage the humidity in it separately from the rest
of the basement.

PS: Here is a good webcalculator:

http://go.vaisala.com/humiditycalculator/5.0/




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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 8:02 AM, John Hawkinson wrote:

jimlux  wrote on Thu, 27 Oct 2016
at 07:51:37 -0700 in :


(and frankly, if someone made something that opened/closed my
windows, I'd love that too, for the same reason.


http://www.mcmaster.com/#motorized-louvers/=14s2pox


No, the existing  windows - we need to be able to see out of it.. We 
have the usual aluminum frame sliding windows.



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Re: [time-nuts] Temp/Humidity control systems

[Scott Stobbe]

I'm not sure I follow the insulation is bad argument, thermal time constant
= RC, better insulation, longer time constant.

On Thu, Oct 27, 2016 at 12:37 PM, Mike Naruta AA8K  wrote:

> On 10/27/2016 03:41 AM, Poul-Henning Kamp wrote:
>
>> Over insulating is a 100% sure-fire way to get unstable temperature
>> inside,
>> because it amplifies the consequences of any change in power dissipation.
>>
>> It is a classic mistake to build a 100mm insulated enclosure inside an
>> office-like environment and end up having less stable temperature on
>> the inside than the outside.
>>
>> Cinder blocks is a much better material for that scenario, because they
>> have both thermal mass and inertia (= heat capacity and heat impedance)
>>
>
>
> True Poul-Henning Kamp.
>
>
> My application was to ecologically stabilize a room exposed to outside
> weather.  I am pleased to see the heater rarely come on, even on cold
> Winter days.  I attribute that to the insulation and equipment mass
> (half-century old computer, avionics, and amateur radio equipment).  Even
> in the Summer heat, the room stays cooler than air temperature (barn roof
> and day/night averaging?).
>
> John's Georgia basement may also enjoy natural cooling and thermal
> inertia.  Cinder blocks may be optimal.  We really need to know John's goal
> and existing conditions.
>
>
>
> Mike - AA8K
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Re: [time-nuts] Temp/Humidity control systems

[Mike Naruta AA8K]

On 10/27/2016 03:41 AM, Poul-Henning Kamp wrote:

Over insulating is a 100% sure-fire way to get unstable temperature inside,
because it amplifies the consequences of any change in power dissipation.

It is a classic mistake to build a 100mm insulated enclosure inside an
office-like environment and end up having less stable temperature on
the inside than the outside.

Cinder blocks is a much better material for that scenario, because they
have both thermal mass and inertia (= heat capacity and heat impedance)



True Poul-Henning Kamp.


My application was to ecologically stabilize a room exposed to 
outside weather.  I am pleased to see the heater rarely come on, 
even on cold Winter days.  I attribute that to the insulation 
and equipment mass (half-century old computer, avionics, and 
amateur radio equipment).  Even in the Summer heat, the room 
stays cooler than air temperature (barn roof and day/night 
averaging?).


John's Georgia basement may also enjoy natural cooling and 
thermal inertia.  Cinder blocks may be optimal.  We really need 
to know John's goal and existing conditions.



Mike - AA8K
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Re: [time-nuts] Temp/Humidity control systems?

[Paul Alfille]

Use one of the Wine cellar room coolers -- they keep the temperature and
humidity fairly constant. Typically ~55F but can vary it. Breezaire and
others are vendors in this area. The units look like a window
airconditioner.

This will work to keep the temperature in a given range, but with rather
abrupt on/off cycles.

If you want a steady temperature, it seems like you need a  lot of thermal
mass and insulation.

On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR  wrote:

> I may have the opportunity to build a small "clock room" and am
> considering whether I could make it an environmentally controlled space.
> I'd like to learn about the options for doing this.
>
> The space would probably be 6x8 feet or so, in a basement with one outside
> wall.
>
> Can anyone point me to purveyors of the hardware to do something like
> this?  Because I'll have a limited time to build this, I'm looking for
> something that uses more-or-less off the shelf gear, and not a whole lot of
> custom engineering.
>
> Thanks!
> John
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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

Mine were 8' x 10' x 7'. "Local pickup only"  ;)
The -20F chamber was 4' x 4' x 7'.
The -80F chamber was 2' x 2' x 5'.

How much space will you need, John? Chances are you could pick up a small
one on ebay and avoid all the jackleg schemes.


On Thursday, October 27, 2016, Poul-Henning Kamp  wrote:

> 
> In message <
> cany2ixrmyy2e9pbdgcqiuzgne_8rpl4kkuw2j4pdjlbj+j1...@mail.gmail.com
> >
> , "William H. Fite" writes:
>
> >Rick, professional environmental chambers [...]
>
> And they come up on fleabay with surprising regularity.
>
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>


-- 
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Re: [time-nuts] Temp/Humidity control systems?

[John Ackermann N8UR]

On 10/27/2016 11:06 AM, Poul-Henning Kamp wrote:


This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.


I learned this myself last summer.  We have a cottage on northern Lake 
Michigan that is about 100 feet from the water.  There is a walk-out 
basement that gets somewhat damp, though a dehumidifier usually keeps it 
under control.  Last summer I opened the cottage later in the season 
than usual, and the basement was very clammy.  So I decided to open the 
slider doors and turn on a box fan to air things out...


When I came back downstairs a couple of hours later, *standing water* 
had condensed on the cold floor tiles!  I had basically been 
dehumidifying Lake Michigan.  Lesson learned (and I spent the rest of 
the vacation trying to dry things out again).


Thanks for all the other comments in this thread.  I'm absorbing and 
will try to summarize back to the group.


John
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message , jimlux writes:

>Disadvantages:
>1) It leaks
>2) It grows stuff (even with additives to prevent it)

Antifreeze prevented that for me.

>3) you've increased the number of thermal transfers: refrigerator coils 
>to air to water to air to contents of box.  Both of the air:water 
>transfers are not particularly efficient in a "cobbled together in the 
>garage" sort of scenario.

Right, it is not a viable method if you want to burn 100+W in your fridge.
I've made it work up to 50W with little trouble.

>However, for a time-cave - I think it would work great  - cheap 
>airconditioner, large thermal mass buffer, well stirred air.

Absolutely.

But the problem in the basement setting is that the heat ends up
in your basement, which means the air can hold more moisture, which
you really do not want.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Temp/Humidity control systems?

[John Hawkinson]

jimlux  wrote on Thu, 27 Oct 2016
at 07:51:37 -0700 in :

> (and frankly, if someone made something that opened/closed my
> windows, I'd love that too, for the same reason.

http://www.mcmaster.com/#motorized-louvers/=14s2pox

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <837330db-2015-4ae5-8c9c-f444f569f...@n1k.org>, Bob Camp writes:

>Your “time cave” does not have a specific spec on temperature or on humidity.
>You get to pick a number for either one. Anything in the “non condensing” 
>(let’s 
>call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
>probably 
>ok for any gear that I can think of. As long as you *never* go in and out of 
>the 
>cave, comfort in the cave is a non-issue. 

Danger Will Robinson!

Under no circumstances should your dewpoint be above the temperature on
the other side of the door.

If you have 40C at 80% humidity your dew-point temperature is 35C, which means
that whenever you open the door your clock cave will fog up.

If you run your clock cave at 40C, humidity needs to be well below
30% to hold the dewpoint below room tempreatyre.  That is both hard,
expensive and prone to electrostatic discharges.

>Assuming the humidity in the basement is under control (if not, fix that), all 
>I need 
>to do for humidity in the closet is to exchange air with the basement.

"fix that" is usually non-trivial, and from very to horribly expensive.

The cardinal rule is that you should only exchange air (basement/outside,
or cave/basement) when the air outside has lower *ABSOLUTE* humidity.

And I keep stressing that it is *ABSOLUTE* humidity, because people simply
don't pay it enough attention.

25C/40%RH air holds 9.2 g/m³ water ... as does 15C/72%RH air.

This is why a lot of people in costal climates who ventilate their
basement during summer "to dry out the basement" get the exact
opposite result:  The air outside is a lot wetter than on the inside.

One would think that somebody had designed fans to measure this,
but it is expensive: Cheap humidity sensors measure relative humidity
and you need to correct for both temperature and pressure to get
absolute humidity.

And therefore, at the risk of repeating myself again:

If you build your clock cave in the basement, it should be air-tight
and you should manage the humidity in it separately from the rest
of the basement.

PS: Here is a good webcalculator:

http://go.vaisala.com/humiditycalculator/5.0/


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 7:37 AM, Bob Camp wrote:

Hi

Ok, take this with a bit of caution ….

Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” (let’s
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably
ok for any gear that I can think of. As long as you *never* go in and out of the
cave, comfort in the cave is a non-issue.



This is an interesting point.. basically you'd turn your DOCXOs into a 
TOCXO where the third oven is your time cave.. you make the set point 
*above* the surroundings, so all you need to do to hold temperature is 
to add heat - which is much, much more controllable in a gradual way 
than removing heat.


The "two radiators and a pump" approach is appealing - you could set it 
up so that the pump is variable speed. That said, there's a fair amount 
of "custom fabrication" involved: you have to find some suitable 
radiators, make the appropriate fittings and connections to your pump 
and hoses, and arrange for fans to blow through them.  You might be able 
to find something off the shelf - Grainger and McMaster are full of 
interesting things - and things to cool hot water using air blowing 
through the coils are probably a fairly off the shelf item.


And, would using a liquid thermal transfer path be any different than a 
variable speed air vent between inside and outside?



What I'm looking for right now is a suitable controller that will run an 
exhaust fan that fits in a 12x12" (approx) opening when the outside 
temperature is "closer" to my target set point than the inside temp:


In Southern California, the outside air temp moves quite a bit during 
the day and rapidly at the day/night transition, so when the garage is 
hot, and outside is cooler, I'd like to exchange air.  Likewise, if the 
garage is cold (cooled down overnight) and outside is warmer, I'd like 
to exchange air to warm it up.


The standard "differential thermostat" seems to only do one of the 
directions (turn on/off load when T1 -T2 > setpoint and T1 > setpoint), 
and I suppose I could "wire or" two of these,  but it seems there should 
be a 'More clever" off the shelf solution.


(and frankly, if someone made something that opened/closed my windows, 
I'd love that too, for the same reason.. I can cold bias the house in 
the morning, leave the AC off all day with the windows closed, and then 
automatically open the windows in the afternoon/evening when the outside 
temperature drops below the inside temperature setpoint)  In combination 
with Time-of-Use electricity rates (something you should consider in 
temperature regulation of your time cave - "store cold at night"), one 
can cheaply pre-cool the house in "super off peak" time.



(Yes, I could program an Arduino to do this, but then I have to cobble 
up a AC relay, a DC power supply, etc., etc)




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Re: [time-nuts] Temp/Humidity control systems?

[Bob Camp]

Hi

Ok, take this with a bit of caution ….

Your “time cave” does not have a specific spec on temperature or on humidity.
You get to pick a number for either one. Anything in the “non condensing” 
(let’s 
call it < 80%) range for humidity is likely ok. Temperature up to 40C is 
probably 
ok for any gear that I can think of. As long as you *never* go in and out of 
the 
cave, comfort in the cave is a non-issue. 

If I load up the cave with gear that runs up the electric bill, the cave will 
self 
heat to some degree. How much it self heats is unclear. The number will be 
highly
dependent on your situation. Based on things like racks full of gear in out of 
the 
way places, it’s a good bet that it will be 10 to 20 C above the temperature in 
the
rest of the basement. 

Assuming the humidity in the basement is under control (if not, fix that), all 
I need 
to do for humidity in the closet is to exchange air with the basement. Since 
the 
volume isn’t very large and (hopefully) the water flow is modest …. a small fan
should take care of that. 

If the closet is bound by the outside (buried) wall and the basement, both 
should be well
controlled temperatures.  If I plug everything in and let it run, the heat rise 
in August should 
be the heat rise in February. Let’s say that’s a 20C rise. The basement is at 
20 C and
the closet is at 40C. Maybe its more, If it’s less,  you need to buy more 
stuff:)

All I need to do is knock the 40C down to 35C with a small amount of “cooling” 
to 
keep things under control. My “humidity” fan might do that. If not, a very 
simple 
water based heat exchanger with a controlled fan will do the job. You need some 
sort
of fan(s) in the closet anyway. Without them you will never get the gradients 
under
control. A pump, 10’ of tubing and two heat exchangers are not a lot of money. 
There
also isn’t a lot to break if you do it right. 

Why do it this way? No compressors to mess up the local power line and break 
every X years (the fridge in the kitchen died Sunday ….. they do break). No 
super
cold surfaces to mess up humidity. No crazy heat flows to create clod drafts 
and 
fast transients in the closet temperature. 

The obvious downside is that you *do* go in the closet. When you do, everything 
goes a bit off. My guess is that you are actually better off letting it recover 
slowly 
than you are trying to move it back in under 10 minutes …. who knows. One 
solution 
to that would be to sub-divide the closet. The gear to do this is cheap. 

Bob



> On Oct 27, 2016, at 10:06 AM, jimlux  wrote:
> 
> On 10/27/16 6:30 AM, Poul-Henning Kamp wrote:
>> 
>> In message , "David J Taylor" writes:
>> 
>>> You can buy the smallest "window" airconditioner and "plumb" it to your
>>> chamber (I used dryer vent hose, cardboard, and lots of duct tape)
>>> 
>>> Attached is a plot temperature and RH of an insulated box about 1.2
>>> meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
>>> bottles of liquid.
>> 
>> You can do *much* better with an old fridge and a small waterpump to
>> circulate water in the cooling loop.
>> 
> 
> 
> I tried that first...
> 
> Advantage is that the mass of the water (serving as a thermal transfer 
> medium) is much greater than that of air.  You wind up with kilos of water at 
> a relatively constant temperature.
> 
> Disadvantages:
> 1) It leaks
> 2) It grows stuff (even with additives to prevent it)
> 3) you've increased the number of thermal transfers: refrigerator coils to 
> air to water to air to contents of box.  Both of the air:water transfers are 
> not particularly efficient in a "cobbled together in the garage" sort of 
> scenario.
> 
> I think your suggestion of just adding (solid) mass to the system is better - 
> the advice to people with wine cellars is to fill empty slots with bottles 
> filled with wine (actually, the advice is to buy more wine, so your cellar 
> doesn't have any empty slots.. but if that's not possible, fill the empties 
> with water, recork and stow them)
> 
> The challenge with a refrigerator as chiller is that getting decent coupling 
> from the cooler coils to the water is tough: you're pretty much restricted to 
> air as the transfer medium.  In a "real chiller" they put the evaporator 
> coils in the water so there's good thermal contact. Refrigerators/freezers 
> aren't made for this - I tried 3 different approaches of varying complexity:
> 
> 1) Put a 5 gallon plastic bucket of water in the refrigerator - the bucket of 
> water does get cold, but--- it also evaporates inside the refrigerator, and 
> the water condenses on the coils, freezes, and then eventually is lost to the 
> air when the unit is defrosted.
> 
> 2) Put an array of copper tubing in close contact with the cold plate in the 
> freezer, weighted down by bricks to make close contact - well, let's just say 
> I found all sorts of interesting galvanic reactions can occur, 

Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 6:30 AM, Poul-Henning Kamp wrote:


In message , "David J Taylor" writes:


You can buy the smallest "window" airconditioner and "plumb" it to your
chamber (I used dryer vent hose, cardboard, and lots of duct tape)

Attached is a plot temperature and RH of an insulated box about 1.2
meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
bottles of liquid.


You can do *much* better with an old fridge and a small waterpump to
circulate water in the cooling loop.




I tried that first...

Advantage is that the mass of the water (serving as a thermal transfer 
medium) is much greater than that of air.  You wind up with kilos of 
water at a relatively constant temperature.


Disadvantages:
1) It leaks
2) It grows stuff (even with additives to prevent it)
3) you've increased the number of thermal transfers: refrigerator coils 
to air to water to air to contents of box.  Both of the air:water 
transfers are not particularly efficient in a "cobbled together in the 
garage" sort of scenario.


I think your suggestion of just adding (solid) mass to the system is 
better - the advice to people with wine cellars is to fill empty slots 
with bottles filled with wine (actually, the advice is to buy more wine, 
so your cellar doesn't have any empty slots.. but if that's not 
possible, fill the empties with water, recork and stow them)


The challenge with a refrigerator as chiller is that getting decent 
coupling from the cooler coils to the water is tough: you're pretty much 
restricted to air as the transfer medium.  In a "real chiller" they put 
the evaporator coils in the water so there's good thermal contact. 
Refrigerators/freezers aren't made for this - I tried 3 different 
approaches of varying complexity:


1) Put a 5 gallon plastic bucket of water in the refrigerator - the 
bucket of water does get cold, but--- it also evaporates inside the 
refrigerator, and the water condenses on the coils, freezes, and then 
eventually is lost to the air when the unit is defrosted.


2) Put an array of copper tubing in close contact with the cold plate in 
the freezer, weighted down by bricks to make close contact - well, let's 
just say I found all sorts of interesting galvanic reactions can occur, 
even at low temperatures - the other problem is that if the circulation 
rate slows, the water in the loop can freeze, and once it starts to 
freeze, it has positive feedback - the flow rate slows even more, and 
pretty quickly, you have tubes full of frozen coolant.  - it is a good 
thing I was doing this in the garage.


3) trying to make a cold plate by using two sheets of aluminum, some 
aluminum spacers, plenty of silicone, and some hose barbs is a lot of 
work, and doesn't seem to work much better.


I think one problem is that the refrigerator/freezer control system is 
designed to work off two sensors: one is a air temperature sensor and 
the other is a sensor on the actual evaporator unit (basically, if it 
gets too cold, it shuts off the compressor to prevent low pressure 
damage).  The "design point" for all of this is also probably not 
optimum for moving heat out of your equipment closet.



And that's just the challenge on "improvised water chiller"

Then you have the other "water to air heat exchanger".. serpentine 
tubing would seem to be the best way, but it turns out that this is 
non-trivial to design so that you get even flow rates in multiple loops, 
if you have multiple paths. And, arranging the tubing effectively is 
hard. There's also all the fabrication/leakage/hose connection issues. 
I tried making serpentines out of copper and aluminum tubing that would 
be part of the shelf on which the bottles are piled.  That cools the 
bottom bottles nicely, but the thermal transfer among the bottles is slow.


The best approach to "get cold to all bottles" (or, more correctly, take 
heat from warm bottles" is to have a fan to circulate air among the 
stacked and racked bottles.  Well, once you are rigging up a fan to push 
air through cold tubing (a re-purposed car heating core - more 
fabrication of adapters from one tubing size to another - I had a big 
box of hose clamps, between size adapters, and pieces of hose of all 
sizes).  Remember that this is all wet at one point or another, either 
from leaks or condensation, so stuff corrodes, rusts, etc.


Yep - a $99 window airconditioner bought on sale (about this time of 
year is good, in the Northern Hemisphere) worked just fine.  Plumbing 
air is a lot easier than plumbing water or glycol coolant.  You won't 
get down to <10C because window air conditioners aren't refrigerators - 
the choice of refrigerant and internal components and set point range 
isn't compatible with that (and putting a small heater on the AC's temp 
sensor, which is in the return air flow to the evaporator did not allow 
me to "bias" the set point)



However, for a time-cave - I think it would work great  - 

Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message , "David J Taylor" writes:

>You can buy the smallest "window" airconditioner and "plumb" it to your
>chamber (I used dryer vent hose, cardboard, and lots of duct tape)
>
>Attached is a plot temperature and RH of an insulated box about 1.2
>meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
>bottles of liquid.

You can do *much* better with an old fridge and a small waterpump to
circulate water in the cooling loop.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <20161027131226.0d5a72e62b2c91f2e13b6...@kinali.ch>, Attila Kinali w
rites:

>> Stop!
>> 
>> Over insulating is a 100% sure-fire way to get unstable temperature inside,
>> because it amplifies the consequences of any change in power dissipation.
>> 
>> It is a classic mistake to build a 100mm insulated enclosure inside an
>> office-like enviroment and end up having less stable temperature on
>> the inside than the outside.
>
>No! Don't Stop! :-)
>
>That's why the next section I wrote described how to get rid of the
>excess heat in a controlled fashio. Of course, simply just insulating
>the room without giving it a lot of thermal mass or any form of control
>of the heat production/exchange will not stabilize the room.

Attila,  I did read that.

You are right in a certain set of circumstances, for instance in a
already climate-regulated office space.

But your model is a recipe for grief and disaster if you do it in
a typical basement, on about 2/3 of the inhabited area of the planet
where you cannot ignore the humidity.

In general in a basement, it is a better idea to set up a closed
space and manage the humidity inside it, than it is to move the
humidity in and out of it.


WRT to humidity, that's a very unlinear relationship, but you can
get far by remembering these five rules:

* Warm air holds more *absolute* humidity (ie: g/m³) than colder air.

* At the same temperture, wetter air is lighter than dryer air.

* The temperature is never the same.

* Condensation should be avoided, period.

* You cannot "feel" absolute humidity, always measure it.

And yes, go ahead and look up number two, it's true.  Dehumidifiers
belong on shelves under the ceiling, not on the floor.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 2:43 AM, Neville Michie wrote:

The nature of air is that when you heat it by one degree Celcius the humidity 
falls by 10%.
That does not change the moisture content of the air, just the activity of the 
same amount of
water vapour with regards to any material with an equilibrium moisture content.
So it is important to control temperature fluctuation if you are going to 
control relative humidity.
cheers,



In this particular case, I did do the calculation of "mass fraction of 
water" from the data - the AC really does pull the water out of the air. 
 The "test article" in this case has relatively small air volume, and a 
large surface area of wood.  Water goes out fast, comes in slow.


There might also be a surface condensation issue on the glass surfaces.

If you look at the wet bulb temperature, it runs a few degrees below the 
air temperature, except when the AC is on, when it plunges several 
degrees in seconds.






Neville Michie



On 27 Oct 2016, at 8:17 PM, David J Taylor  
wrote:

From: jimlux

You can buy the smallest "window" airconditioner and "plumb" it to your
chamber (I used dryer vent hose, cardboard, and lots of duct tape)

Attached is a plot temperature and RH of an insulated box about 1.2
meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
bottles of liquid.

The temperature is fairly stable, but the RH varies wildly - basically,
when the AC unit kicks on, it sucks all the water out of the air in the
box, and then, when it turns off, the (damp) walls of the box rapidly
rehumidify the air.
___

Thanks for that, Jim, and for the graph.

Your graph suggests to me that using /any/ form of artificial control may give worse 
short-term results than simply leaving an underground, uninhabited room with outside 
walls just "as-is".  The slow daily variations may be far more tolerable than 
excursions due to heaters etc. being switched on and off.

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/27/16 2:17 AM, David J Taylor wrote:

From: jimlux

You can buy the smallest "window" airconditioner and "plumb" it to your
chamber (I used dryer vent hose, cardboard, and lots of duct tape)

Attached is a plot temperature and RH of an insulated box about 1.2
meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
bottles of liquid.

The temperature is fairly stable, but the RH varies wildly - basically,
when the AC unit kicks on, it sucks all the water out of the air in the
box, and then, when it turns off, the (damp) walls of the box rapidly
rehumidify the air.
___

Thanks for that, Jim, and for the graph.

Your graph suggests to me that using /any/ form of artificial control
may give worse short-term results than simply leaving an underground,
uninhabited room with outside walls just "as-is".  The slow daily
variations may be far more tolerable than excursions due to heaters etc.
being switched on and off.




Indeed.. a large mass varies slowly.

(hence the suggestions in previous years for finding caves, digging a 
mine shaft, etc)


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Re: [time-nuts] Temp/Humidity control systems?

[Attila Kinali]

Hoi Poul-Henning,

On Thu, 27 Oct 2016 07:41:48 +
"Poul-Henning Kamp"  wrote:

> >Probably the easiest is to get some glass/mineral wool insulation and
> >put it over all the walls, including ceiling and floor. I do not recommend
> >any foam or styropor based insulation as almost all of them are inflamable.
> >This should get you into the area of 10-100W/K thermal resistance for your
> >closet (assuming something like 4cm thick insulation gets about 40W/K).
> 
> Stop!
> 
> Over insulating is a 100% sure-fire way to get unstable temperature inside,
> because it amplifies the consequences of any change in power dissipation.
> 
> It is a classic mistake to build a 100mm insulated enclosure inside an
> office-like enviroment and end up having less stable temperature on
> the inside than the outside.

No! Don't Stop! :-)

That's why the next section I wrote described how to get rid of the
excess heat in a controlled fashio. Of course, simply just insulating
the room without giving it a lot of thermal mass or any form of control
of the heat production/exchange will not stabilize the room.


Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

The nature of air is that when you heat it by one degree Celcius the humidity 
falls by 10%.
That does not change the moisture content of the air, just the activity of the 
same amount of 
water vapour with regards to any material with an equilibrium moisture content.
So it is important to control temperature fluctuation if you are going to 
control relative humidity.
cheers,
Neville Michie


> On 27 Oct 2016, at 8:17 PM, David J Taylor  
> wrote:
> 
> From: jimlux
> 
> You can buy the smallest "window" airconditioner and "plumb" it to your
> chamber (I used dryer vent hose, cardboard, and lots of duct tape)
> 
> Attached is a plot temperature and RH of an insulated box about 1.2
> meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
> bottles of liquid.
> 
> The temperature is fairly stable, but the RH varies wildly - basically,
> when the AC unit kicks on, it sucks all the water out of the air in the
> box, and then, when it turns off, the (damp) walls of the box rapidly
> rehumidify the air.
> ___
> 
> Thanks for that, Jim, and for the graph.
> 
> Your graph suggests to me that using /any/ form of artificial control may 
> give worse short-term results than simply leaving an underground, uninhabited 
> room with outside walls just "as-is".  The slow daily variations may be far 
> more tolerable than excursions due to heaters etc. being switched on and off.
> 
> Cheers,
> David
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv 
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Re: [time-nuts] Temp/Humidity control systems?

[David J Taylor]

From: jimlux

You can buy the smallest "window" airconditioner and "plumb" it to your
chamber (I used dryer vent hose, cardboard, and lots of duct tape)

Attached is a plot temperature and RH of an insulated box about 1.2
meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml
bottles of liquid.

The temperature is fairly stable, but the RH varies wildly - basically,
when the AC unit kicks on, it sucks all the water out of the air in the
box, and then, when it turns off, the (damp) walls of the box rapidly
rehumidify the air.
___

Thanks for that, Jim, and for the graph.

Your graph suggests to me that using /any/ form of artificial control may 
give worse short-term results than simply leaving an underground, 
uninhabited room with outside walls just "as-is".  The slow daily variations 
may be far more tolerable than excursions due to heaters etc. being switched 
on and off.


Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <20161026210517.26c0fd397b1cae5ba9c12...@kinali.ch>, Attila Kinali w
rites:

>Probably the easiest is to get some glass/mineral wool insulation and
>put it over all the walls, including ceiling and floor. I do not recommend
>any foam or styropor based insulation as almost all of them are inflamable.
>This should get you into the area of 10-100W/K thermal resistance for your
>closet (assuming something like 4cm thick insulation gets about 40W/K).

Stop!

Over insulating is a 100% sure-fire way to get unstable temperature inside,
because it amplifies the consequences of any change in power dissipation.

It is a classic mistake to build a 100mm insulated enclosure inside an
office-like enviroment and end up having less stable temperature on
the inside than the outside.

Cinderblocks is a much better material for that scenario, because they
have both thermal mass and inertia (= heat capacity and heat impedance)

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message 
, "William H. Fite" writes:

>Rick, professional environmental chambers [...]

And they come up on fleabay with surprising regularity.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Temp/Humidity control systems?

[Poul-Henning Kamp]

In message <5810d2d2.2070...@febo.com>, John Ackermann N8UR writes:

>I may have the opportunity to build a small "clock room" and am 
>considering whether I could make it an environmentally controlled space. 
>  I'd like to learn about the options for doing this.

You first need to decide what kind of clock room you want:

At one extreme you have a clock vault you never change anything in,
with incredibly stable temperature & humidity, but stabilization
times of days or weeks.

At the other end you have an environmental chamber which hits temperature
and humidity in a matter of minutes after you closed them.

If you want to do this low budget, consider getting a couple of old
fridges or freezers and run water of your chosen temperature
through their cooling loops.  That way you can have multiple different
climates and keep soom stuff stable while you play with other stuff.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

vinotemp.com has all the bits and pieces.  but you're not going to get 1 degree 
control
a 6500 btu/hr air-conditioned is a lot cheaper than a 1500 btu/hr wine cooler 
unit


Sent via the Samsung Galaxy S®6 active, an AT 4G LTE smartphone
 Original message From: Bob Camp <kb...@n1k.org> Date: 10/26/16 
 4:00 PM  (GMT-07:00) To: Discussion of precise time and frequency measurement 
<time-nuts@febo.com> Subject: Re: [time-nuts] Temp/Humidity control systems? 
HI

I would take a look at the “stuff” they make for wine cellars. It’s an 
application aimed 
at the same sort of area size and done in much higher volume than an 
electronics 
closet. 

Bob

> On Oct 26, 2016, at 1:58 PM, John Ackermann N8UR <j...@febo.com> wrote:
> 
> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>> I may have the opportunity to build a small "clock room" and am
>>> considering whether I could make it an environmentally controlled space.
>>> I'd like to learn about the options for doing this.
>>> 
>>> The space would probably be 6x8 feet or so, in a basement with one
>>> outside wall.
>> 
>> I'm lost with the basic concept here.  Help me understand this.
> 
> This room would be a large closet in my basement where two racks of various 
> OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out traffic. I'm not 
> looking for 0.01 degree regulation -- <1 degree C and a few percent humidity 
> throughout the year seems a reasonable goal.
> 
> What I envisioned was a very small heat pump or other heating/air-con unit 
> coupled with some sort of proportional control. I just don't know where to 
> start looking for that, or what other issues to be thinking about.
> 
> (I know the way time-nuts think, and I recall the great ideas posted here in 
> the past about using an old refrigerator, or burying standards in a deep hole 
> -- but this would be wrapped into a bigger construction project that I'm 
> going to be managing from a distance, so I need to keep it fairly 
> straight-forward.)
> 
> Thanks, all!
> 
> John
> 
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Re: [time-nuts] Temp/Humidity control systems?

[Bob Camp]

HI

I would take a look at the “stuff” they make for wine cellars. It’s an 
application aimed 
at the same sort of area size and done in much higher volume than an 
electronics 
closet. 

Bob

> On Oct 26, 2016, at 1:58 PM, John Ackermann N8UR  wrote:
> 
> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>> I may have the opportunity to build a small "clock room" and am
>>> considering whether I could make it an environmentally controlled space.
>>> I'd like to learn about the options for doing this.
>>> 
>>> The space would probably be 6x8 feet or so, in a basement with one
>>> outside wall.
>> 
>> I'm lost with the basic concept here.  Help me understand this.
> 
> This room would be a large closet in my basement where two racks of various 
> OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out traffic. I'm not 
> looking for 0.01 degree regulation -- <1 degree C and a few percent humidity 
> throughout the year seems a reasonable goal.
> 
> What I envisioned was a very small heat pump or other heating/air-con unit 
> coupled with some sort of proportional control. I just don't know where to 
> start looking for that, or what other issues to be thinking about.
> 
> (I know the way time-nuts think, and I recall the great ideas posted here in 
> the past about using an old refrigerator, or burying standards in a deep hole 
> -- but this would be wrapped into a bigger construction project that I'm 
> going to be managing from a distance, so I need to keep it fairly 
> straight-forward.)
> 
> Thanks, all!
> 
> John
> 
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Re: [time-nuts] Temp/Humidity control systems?

[Scott Stobbe]

If your instruments/clocks were insensitive to variations in line voltage
you could vary your rooms line voltage with a variable auto transformer
(end up being a heater with tons of surface area). Or pack enough OCXOs in
there so they end up thermally servoing the room.

On Wednesday, 26 October 2016, jimlux  wrote:

> On 10/26/16 10:58 AM, John Ackermann N8UR wrote:
>
>> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>>
>>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>>
 I may have the opportunity to build a small "clock room" and am
 considering whether I could make it an environmentally controlled space.
  I'd like to learn about the options for doing this.

 The space would probably be 6x8 feet or so, in a basement with one
 outside wall.

>>>
>>> I'm lost with the basic concept here.  Help me understand this.
>>>
>>
>> This room would be a large closet in my basement where two racks of
>> various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out
>> traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a
>> few percent humidity throughout the year seems a reasonable goal.
>>
>>
> Heating is easy (proportional control of a resistive heater)
>
> 1C is going to be very tough unless you have some way to variably mix cold
> dry air from your cooler with room air.  Air conditioners don't like being
> short cycled.
> The challenge is that "cold" is usually available in a bang/bang way, so
> you need something to low pass filter it.
>
> If you had a large source of cold water, you could use a proportional
> control valve and some sort of radiator with a fan.
>
> Or, have a massive thermal sink between your "controlled space" and "where
> the ac unit is".. If you imagine a meter thick slab of, say, Gold (good
> conductivity, very high density), it would act as a very effective low pass
> filter between the cycling of your AC unit and your controlled space.
>
> I started my control system by putting a 5 gallon bucket of water in a
> refrigerator, and then using a variable speed pump into a radiator in the
> chamber.  This worked quite well, but you run into all the problems with a
> liquid loop system: stuff grows in the water, water corrodes stuff, it
> leaks, etc.
>
>
>
>
>
>
>
> What I envisioned was a very small heat pump or other heating/air-con
>> unit coupled with some sort of proportional control. I just don't know
>> where to start looking for that, or what other issues to be thinking
>> about.
>>
>> (I know the way time-nuts think, and I recall the great ideas posted
>> here in the past about using an old refrigerator, or burying standards
>> in a deep hole -- but this would be wrapped into a bigger construction
>> project that I'm going to be managing from a distance, so I need to keep
>> it fairly straight-forward.)
>>
>> Thanks, all!
>>
>> John
>> 
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/26/16 1:39 PM, Mark Sims wrote:

There is also the old trick of having an AC unit running continuously, but 
blowing through a controlled heater.  Not the most efficient setup...  I think 
that even TVB has implemented such a contraption...



That's how automotive A/C works..

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[time-nuts] Temp/Humidity control systems?

[Mark Sims]

There is also the old trick of having an AC unit running continuously, but 
blowing through a controlled heater.  Not the most efficient setup...  I think 
that even TVB has implemented such a contraption... 
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/26/16 9:34 AM, David J Taylor wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.

Can anyone point me to purveyors of the hardware to do something like
this?  Because I'll have a limited time to build this, I'm looking for
something that uses more-or-less off the shelf gear, and not a whole lot
of custom engineering.

Thanks!
John
___

John,

My most stable systems are in an upstairs, walk-in cupboard with two
outside walls.  If the space is normally unoccupied, you may find it
stable enough. Can you put a temperature recorder in the space to
check?  I've used a Raspberry Pi and "single wire" sensor for this.





You can buy the smallest "window" airconditioner and "plumb" it to your 
chamber (I used dryer vent hose, cardboard, and lots of duct tape)


Attached is a plot temperature and RH of an insulated box about 1.2 
meter wide, 2 meters tall and 60 cm deep, filled with 100 or so 750 ml 
bottles of liquid.


The temperature is fairly stable, but the RH varies wildly - basically, 
when the AC unit kicks on, it sucks all the water out of the air in the 
box, and then, when it turns off, the (damp) walls of the box rapidly 
rehumidify the air.




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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/26/16 10:58 AM, John Ackermann N8UR wrote:

On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:

On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.


I'm lost with the basic concept here.  Help me understand this.


This room would be a large closet in my basement where two racks of
various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out
traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a
few percent humidity throughout the year seems a reasonable goal.



Heating is easy (proportional control of a resistive heater)

1C is going to be very tough unless you have some way to variably mix 
cold dry air from your cooler with room air.  Air conditioners don't 
like being short cycled.
The challenge is that "cold" is usually available in a bang/bang way, so 
you need something to low pass filter it.


If you had a large source of cold water, you could use a proportional 
control valve and some sort of radiator with a fan.


Or, have a massive thermal sink between your "controlled space" and 
"where the ac unit is".. If you imagine a meter thick slab of, say, Gold 
(good conductivity, very high density), it would act as a very effective 
low pass filter between the cycling of your AC unit and your controlled 
space.


I started my control system by putting a 5 gallon bucket of water in a 
refrigerator, and then using a variable speed pump into a radiator in 
the chamber.  This worked quite well, but you run into all the problems 
with a liquid loop system: stuff grows in the water, water corrodes 
stuff, it leaks, etc.









What I envisioned was a very small heat pump or other heating/air-con
unit coupled with some sort of proportional control. I just don't know
where to start looking for that, or what other issues to be thinking about.

(I know the way time-nuts think, and I recall the great ideas posted
here in the past about using an old refrigerator, or burying standards
in a deep hole -- but this would be wrapped into a bigger construction
project that I'm going to be managing from a distance, so I need to keep
it fairly straight-forward.)

Thanks, all!

John

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Re: [time-nuts] Temp/Humidity control systems?

[Neville Michie]

Hi John,

such a project is quite practical.
I spent a working lifetime in textile physics research.
Air conditioned rooms were in great demand and access was limited.
So I did what I could with what I could get.
In spite of what conventional wisdom (or lack of wisdom ) says you 
can get good performance from a reverse cycle window air conditioner unit.
For humidity control, you should be able to make do with unilateral control 
downwards,
set the room to a humidity that is lower than the lowest ambient humidity. You 
may even compromise
by setting humidity at say 40% and tolerate the rare occasion that it drops 
below. It may be worth it 
so avoid the mess of bilateral control.
Now, so far you have the recipe for a system that produces great swings in 
temperature and humidity,
not what you want.
The important step is the controller and a small fan or two that gently swirls 
the air around the room,
at a velocity about 0.5m/s, which is only just on the threshold of perception. 
The swirling of the air 
means that within a time frame of 30 seconds the air is mixed into one thermal 
mass.
The control has several requirements.
The temperature must have a very rapid response time one or two seconds. A very 
small glass 
encapsulated thermistor in the general air flow are used. Thin film humidity 
sensors can be fast 
enough for humidity control.
The controller is directed at motor control. 
The motors are switched with substantial zero voltage switching solid state 
relays, - no QRM.
The rules are for both motors, the motor can be switched 
on within a second of the control temperature being reached, but only if a 
“decompression time” has elapsed.
No noisy switching is possible because any on signal starts the decompression 
timer.
This would be about 2 minutes for a window unit. This is necessary to avoid 
harm to the compressor through
over frequent cycling, and it does not have to start under load.
This may seem catastrophic for control, but the 
result is benign.
The fan in the window unit and dehumidifier are left running, probably on “low”.
Changeover from heating to cooling on the reverse cycle unit occurs 
automatically when a 6 minute timer 
detects no motor operation. This may seem a bit slow, but it happens at a time 
when heating or 
cooling are hardly needed.
How it works: Your 2 * 3 * 3 metre room contains 18 Kg of air, effectively in a 
single mass.
When the window unit cuts in the temperature rises of falls at a constant rate 
of about 2 degrees per minute. When the 
set point is crossed this ramp will stop within a few seconds. The temperature 
then slowly falls or rises
until after 2 minutes IF it is on the wrong side of the set point the motor 
starts up again.
Typically the motor runs 15 seconds and stays off for 200.
My rooms had an average temperature that did not shift more than a tenth of a 
C. They only used the minimum power 
needed, when required, peak variation was about 0.5C. Remember you have to keep 
the air volume mixed.
The thermometer was mounted in the general air stream about half way around the 
loop from the AC unit around the room.
One of my rooms had 30% windows and double brick walls but not other insulation.
The window units did not have shortened lives because of the “frequent cycling” 
because they were started under the right conditions.
I did publish this 30 or 40 years ago in an Australian electronics magazine.

cheers,
Neville Michie



> On 27 Oct 2016, at 2:59 AM, John Ackermann N8UR  wrote:
> 
> I may have the opportunity to build a small "clock room" and am considering 
> whether I could make it an environmentally controlled space.  I'd like to 
> learn about the options for doing this.
> 
> The space would probably be 6x8 feet or so, in a basement with one outside 
> wall.
> 
> Can anyone point me to purveyors of the hardware to do something like this?  
> Because I'll have a limited time to build this, I'm looking for something 
> that uses more-or-less off the shelf gear, and not a whole lot of custom 
> engineering.
> 
> Thanks!
> John
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Re: [time-nuts] Temp/Humidity control systems?

[jimlux]

On 10/26/16 8:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.

Can anyone point me to purveyors of the hardware to do something like
this?  Because I'll have a limited time to build this, I'm looking for
something that uses more-or-less off the shelf gear, and not a whole lot
of custom engineering.


How tightly regulated?

I've been looking into this to make a chamber of that general size that 
is around 10-15C and 50% RH  (for incubating sausage duplicating an 
Italian cave)...


Most kitchen stuff (refrigerators, etc.) tend to have fairly big 
fluctuations of temperature as the compressor cycles, although if you 
put a lot of mass in the controlled space that certainly slows it down.


There are also a variety of things like cold storage (for florists, for 
example) - they tend to be assembled out of simple building blocks: 
insulated wall panels, a cooler unit, a door.


Lab incubators or commercial baking is another source (imagine raising 
bread consistently)


However, all these kinds of applications can easily tolerate a 5C swing 
in temperature since the thing being controlled is fairly massive and 
its internal temperature will vary less.


The challenge with a "small" space is that when the cooling unit comes 
on, you're blasting in cold air, and it's not "well mixed".











Thanks!
John
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Re: [time-nuts] Temp/Humidity control systems?

[Eric Garner]

I would start looking at the ductless heat pump systems that are becoming
popular now they don't take up much space, have pretty good capacity and
are efficient. I have no idea if they can be proportionally controlled or
what the temperature hysteresis on them are though, which might be an issue
in a room the size of a sheet of plywood.

On Wed, Oct 26, 2016 at 10:58 AM, John Ackermann N8UR  wrote:

> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>
>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>
>>> I may have the opportunity to build a small "clock room" and am
>>> considering whether I could make it an environmentally controlled space.
>>>  I'd like to learn about the options for doing this.
>>>
>>> The space would probably be 6x8 feet or so, in a basement with one
>>> outside wall.
>>>
>>
>> I'm lost with the basic concept here.  Help me understand this.
>>
>
> This room would be a large closet in my basement where two racks of
> various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out traffic.
> I'm not looking for 0.01 degree regulation -- <1 degree C and a few percent
> humidity throughout the year seems a reasonable goal.
>
> What I envisioned was a very small heat pump or other heating/air-con unit
> coupled with some sort of proportional control. I just don't know where to
> start looking for that, or what other issues to be thinking about.
>
> (I know the way time-nuts think, and I recall the great ideas posted here
> in the past about using an old refrigerator, or burying standards in a deep
> hole -- but this would be wrapped into a bigger construction project that
> I'm going to be managing from a distance, so I need to keep it fairly
> straight-forward.)
>
> Thanks, all!
>
> John
> 
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
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> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
--Eric
_
Eric Garner
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Re: [time-nuts] Temp/Humidity control systems?

[Attila Kinali]

On Wed, 26 Oct 2016 13:58:10 -0400
John Ackermann N8UR  wrote:

> This room would be a large closet in my basement where two racks of 
> various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out 
> traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a 
> few percent humidity throughout the year seems a reasonable goal.
> 
> What I envisioned was a very small heat pump or other heating/air-con 
> unit coupled with some sort of proportional control. I just don't know 
> where to start looking for that, or what other issues to be thinking about.

Probably the easiest is to get some glass/mineral wool insulation and
put it over all the walls, including ceiling and floor. I do not recommend
any foam or styropor based insulation as almost all of them are inflamable.
This should get you into the area of 10-100W/K thermal resistance for your
closet (assuming something like 4cm thick insulation gets about 40W/K).
Yous should put some vapor barrier on the inside of the insulation, as
otherwise you will get mold between the insulation and wall.

Assuming you have gear that generates 1-2kW of heat, that means you are
in the region of 100K to 10K above outside temperature. Now all you have
to do is getting the heat out. This can be easily done with an PWM fan
controller which you get for a couple of bucks on ebay/aliexpress. 

In case you don't get enough heat inside, just add some heating element
that you run with constant power (eg a hair dryer run from a constant
current source).

I wouldn't go for A/C systems, as these need quite a bit of hysteresis
to work properly (2-3°C) and the switch on/switch off spikes will cause
all kind of headaches.

For added stability, fill the empty space in the closet with half-liter
PET water bottles and place a small fan blowing at them.

As for humidity control.. Guessing from where I think you live, you will have
a wide range of ambient humidity, which means you need to be able to both
control it up and down. The easiest solution there is to have an humidifier
constantly running (please use one that evaporates instead of sprays,
the latter is a good way to spread bacteria and mold everywhere. ultrasonic
devices are spraying) and use a controllable dehumidifier (they are available
for 100€) take the excess humidity out again. 

As I mentioned, bacteria and mold are a problem with those. Either you
need to make sure that the water used in the humidifier is always fresh
and the water extracted from the dehumidifier gets discarded somewhere,
or you need to sterilize the water if you let it sit or, even worse,
circulate. Probably the easiest way to sterilize is UV light, but it
degrades all kind of materials, especially plastic.

All of this should be doable with 200-500€ and whithin a long weekend.


HTH

Attila Kinali

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

Rick, professional environmental chambers and their contents have a great
deal of thermal inertia. In addition, they have overbuilt refrigeration
systems, electric heaters, and de/humidifiers. You teach your lab rats to
enter the chambers as infrequently as possible, to close the doors as
quickly as possible, to assure that materials brought into the chamber are
as near as is practical to chamber temperature, avoid bringing open liquids
in, etc. A good chamber will easily hold +/- 1C and +/- 2% RH in free air,
even with powered equipment inside cycling on and off and occasional
entries. An air lock wouldn't help as much as you might think because the
human body is a much larger heat reservoir than the air that might be
exchanged while the door is open. Keep in mind, too, that most
chambers--certainly the ones that would interest John--are intended to
maintain stability fairly near external ambient conditions. High and low
temperature chambers are a whole different species of animal.

On Wednesday, October 26, 2016, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:

> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>
>> I may have the opportunity to build a small "clock room" and am
>> considering whether I could make it an environmentally controlled space.
>>  I'd like to learn about the options for doing this.
>>
>> The space would probably be 6x8 feet or so, in a basement with one
>> outside wall.
>>
>>
> I'm lost with the basic concept here.  Help me understand this.
>
> If you go in and out of this room through a door, I don't
> know how you prevent large fluctuations in temp/humidity.
> You would probably need an air lock.
>
> Is it a "room" where humans go, or just a "chamber" that is
> locked up most of the time?
>
> Rick N6RK
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-- 
If you gaze long into an abyss, your coffee will get cold.
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Re: [time-nuts] Temp/Humidity control systems

[Mike Naruta AA8K]

On 10/26/2016 11:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally
controlled space.  I'd like to learn about the options for doing
this.

The space would probably be 6x8 feet or so, in a basement with
one outside wall.

Can anyone point me to purveyors of the hardware to do something
like this?  Because I'll have a limited time to build this, I'm
looking for something that uses more-or-less off the shelf gear,
and not a whole lot of custom engineering.

Thanks!
John
___



I built a "ham shack" room in my unheated barn.  8 by 12 feet, 
interior lined with sheets of foil-backed foam insulation board, 
then plywood over the insulation.  Walls, ceiling, and floor.  A 
600 watt portable heater is more than enough to keep it 
comfortable in the Michigan winter (-26F -32C in 2015)  This is 
with no equipment turned on.  You problem will likely be getting 
rid of heat.  A small, through-wall air conditioner might be a 
cheap way of doing it.  Place the chiller outside the house. 
The trick is to reduce the hunt differential.  Might be easy to 
build your own thermostat circuit to control the compressor. 
Another option might be a small window air conditioner dumping 
into the basement.  That way you don't have to plumb the 
refrigerant lines.


I don't know how humid it gets in Snellville, but the air 
conditioner should take out the humidity.


At the end opposite the door, I have a bathroom-type exhaust fan 
in the ceiling if it gets too unpleasant inside.  I have a 
tunnel over the fan with acoustic foam inside to reduce fan noise.


When I installed the sheets of foil-backed insulation, I put 
expanded aluminum mesh over the gaps.  It's a fairly-effective 
Faraday cage too.  Sealing the door was a bit tricky, but when I 
close it, signals decrease.  Useful when you have three 
broadcast transmitters in the neighborhood.


Mike - AA8K
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Re: [time-nuts] Temp/Humidity control systems?

[Scott McGrath]

Personally I'd be looking at a commercial ductless heat pump unit Mitsubishi 
MrSlim comes to mind in your case you would want a 'cartridge' type unit 
designed for ceiling mount the ones for data center use have humidity control 
as well.   Figure these units will hold +/- 2-3 deg F over long term

If you really want to go over the top get a used RF shield room.  Lots of used 
ones coming on market as stuff is going over 26Ghz.  Shipping will be the ugly 
bit as the doors are heavy

Content by Scott
Typos by Siri

> On Oct 26, 2016, at 1:58 PM, John Ackermann N8UR  wrote:
> 
>> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>> I may have the opportunity to build a small "clock room" and am
>>> considering whether I could make it an environmentally controlled space.
>>> I'd like to learn about the options for doing this.
>>> 
>>> The space would probably be 6x8 feet or so, in a basement with one
>>> outside wall.
>> 
>> I'm lost with the basic concept here.  Help me understand this.
> 
> This room would be a large closet in my basement where two racks of various 
> OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out traffic. I'm not 
> looking for 0.01 degree regulation -- <1 degree C and a few percent humidity 
> throughout the year seems a reasonable goal.
> 
> What I envisioned was a very small heat pump or other heating/air-con unit 
> coupled with some sort of proportional control. I just don't know where to 
> start looking for that, or what other issues to be thinking about.
> 
> (I know the way time-nuts think, and I recall the great ideas posted here in 
> the past about using an old refrigerator, or burying standards in a deep hole 
> -- but this would be wrapped into a bigger construction project that I'm 
> going to be managing from a distance, so I need to keep it fairly 
> straight-forward.)
> 
> Thanks, all!
> 
> John
> 
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Re: [time-nuts] Temp/Humidity control systems?

[Mark Spencer]

Hi John.   You might want to look at "precision air conditioning" systems (to 
use the vendors phraseology) designed for small computer rooms for some ideas ?

I suspect getting close to your temperature spec may be easier than your 
humidity spec ?   There may also be issues getting commercial units permitted / 
installed / inspected in a residential setting ?

As a side note I was impressed with the split unit my residential HVAC 
contractor installed during a recent Reno in my TV room.  The newer units seem 
to have finer temperature units than the older ones.  I don't believe my unit 
features any humidity control.


Hope this is of some interest.

Mark Spencer

> On Oct 26, 2016, at 10:58 AM, John Ackermann N8UR  wrote:
> 
>> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>> I may have the opportunity to build a small "clock room" and am
>>> considering whether I could make it an environmentally controlled space.
>>> I'd like to learn about the options for doing this.
>>> 
>>> The space would probably be 6x8 feet or so, in a basement with one
>>> outside wall.
>> 
>> I'm lost with the basic concept here.  Help me understand this.
> 
> This room would be a large closet in my basement where two racks of various 
> OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out traffic. I'm not 
> looking for 0.01 degree regulation -- <1 degree C and a few percent humidity 
> throughout the year seems a reasonable goal.
> 
> What I envisioned was a very small heat pump or other heating/air-con unit 
> coupled with some sort of proportional control. I just don't know where to 
> start looking for that, or what other issues to be thinking about.
> 
> (I know the way time-nuts think, and I recall the great ideas posted here in 
> the past about using an old refrigerator, or burying standards in a deep hole 
> -- but this would be wrapped into a bigger construction project that I'm 
> going to be managing from a distance, so I need to keep it fairly 
> straight-forward.)
> 
> Thanks, all!
> 
> John
> 
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Re: [time-nuts] Temp/Humidity control systems?

[Bob Stewart]

Hi John,
Have you looked into walk-in humidors to see if there are any ideas there that 
you could use?  Yeah, those use high levels of humidity, but there might be 
something in common with your needs.

Bob
 -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: John Ackermann N8UR <j...@febo.com>
 To: time-nuts@febo.com 
 Sent: Wednesday, October 26, 2016 12:58 PM
 Subject: Re: [time-nuts] Temp/Humidity control systems?
   
On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>> I may have the opportunity to build a small "clock room" and am
>> considering whether I could make it an environmentally controlled space.
>>  I'd like to learn about the options for doing this.
>>
>> The space would probably be 6x8 feet or so, in a basement with one
>> outside wall.
>
> I'm lost with the basic concept here.  Help me understand this.

This room would be a large closet in my basement where two racks of 
various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out 
traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a 
few percent humidity throughout the year seems a reasonable goal.

What I envisioned was a very small heat pump or other heating/air-con 
unit coupled with some sort of proportional control. I just don't know 
where to start looking for that, or what other issues to be thinking about.

(I know the way time-nuts think, and I recall the great ideas posted 
here in the past about using an old refrigerator, or burying standards 
in a deep hole -- but this would be wrapped into a bigger construction 
project that I'm going to be managing from a distance, so I need to keep 
it fairly straight-forward.)

Thanks, all!

John

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Re: [time-nuts] Temp/Humidity control systems?

[John Ackermann N8UR]

On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:

On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.


I'm lost with the basic concept here.  Help me understand this.


This room would be a large closet in my basement where two racks of 
various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out 
traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a 
few percent humidity throughout the year seems a reasonable goal.


What I envisioned was a very small heat pump or other heating/air-con 
unit coupled with some sort of proportional control. I just don't know 
where to start looking for that, or what other issues to be thinking about.


(I know the way time-nuts think, and I recall the great ideas posted 
here in the past about using an old refrigerator, or burying standards 
in a deep hole -- but this would be wrapped into a bigger construction 
project that I'm going to be managing from a distance, so I need to keep 
it fairly straight-forward.)


Thanks, all!

John

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Re: [time-nuts] Temp/Humidity control systems?

[Scott Stobbe]

I have always wondered how large the market for those hydroponic/indoor
gardening stores really is, maybe they have something to fit the bill.

On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR  wrote:

> I may have the opportunity to build a small "clock room" and am
> considering whether I could make it an environmentally controlled space.
> I'd like to learn about the options for doing this.
>
> The space would probably be 6x8 feet or so, in a basement with one outside
> wall.
>
> Can anyone point me to purveyors of the hardware to do something like
> this?  Because I'll have a limited time to build this, I'm looking for
> something that uses more-or-less off the shelf gear, and not a whole lot of
> custom engineering.
>
> Thanks!
> John
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> ailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] Temp/Humidity control systems?

[Richard (Rick) Karlquist]

On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.



I'm lost with the basic concept here.  Help me understand this.

If you go in and out of this room through a door, I don't
know how you prevent large fluctuations in temp/humidity.
You would probably need an air lock.

Is it a "room" where humans go, or just a "chamber" that is
locked up most of the time?

Rick N6RK
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Re: [time-nuts] Temp/Humidity control systems?

[David J Taylor]

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.

Can anyone point me to purveyors of the hardware to do something like
this?  Because I'll have a limited time to build this, I'm looking for
something that uses more-or-less off the shelf gear, and not a whole lot
of custom engineering.

Thanks!
John
___

John,

My most stable systems are in an upstairs, walk-in cupboard with two outside 
walls.  If the space is normally unoccupied, you may find it stable enough. 
Can you put a temperature recorder in the space to check?  I've used a 
Raspberry Pi and "single wire" sensor for this.


 http://www.satsignal.eu/raspberry-pi/monitoring.html#ambient

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] Temp/Humidity control systems?

[Attila Kinali]

Hoi John,

On Wed, 26 Oct 2016 11:59:14 -0400
John Ackermann N8UR  wrote:

> I may have the opportunity to build a small "clock room" and am 
> considering whether I could make it an environmentally controlled space. 
>   I'd like to learn about the options for doing this.

What is the available budget for time and money?

Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Temp/Humidity control systems?

[John Ackermann N8UR]

Hi Bill --

That's a bit more than I had in mind, but very cool. :-)  What I really 
meant was a heat pump or other unit with good control loop that I could 
use in a standard insulated space, just to keep "nominal" conditions 
(ie, not wide-range testing).


Thanks,
John


On 10/26/2016 12:09 PM, William H. Fite wrote:

John, this is what I bought for the Orlando VA Medical Center when I was
setting up the research lab there.

Not cheap, though.  螺

https://www.thermalproductsolutions.com/products/walk-in-temperature-humidity-test-rooms

On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR  wrote:


I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one outside
wall.

Can anyone point me to purveyors of the hardware to do something like
this?  Because I'll have a limited time to build this, I'm looking for
something that uses more-or-less off the shelf gear, and not a whole lot of
custom engineering.

Thanks!
John
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ailman/listinfo/time-nuts
and follow the instructions there.






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Re: [time-nuts] Temp/Humidity control systems?

[William H. Fite]

John, this is what I bought for the Orlando VA Medical Center when I was
setting up the research lab there.

Not cheap, though.  螺

https://www.thermalproductsolutions.com/products/walk-in-temperature-humidity-test-rooms

On Wed, Oct 26, 2016 at 11:59 AM, John Ackermann N8UR  wrote:

> I may have the opportunity to build a small "clock room" and am
> considering whether I could make it an environmentally controlled space.
> I'd like to learn about the options for doing this.
>
> The space would probably be 6x8 feet or so, in a basement with one outside
> wall.
>
> Can anyone point me to purveyors of the hardware to do something like
> this?  Because I'll have a limited time to build this, I'm looking for
> something that uses more-or-less off the shelf gear, and not a whole lot of
> custom engineering.
>
> Thanks!
> John
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> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Intelligence has never been proof against stupidity.
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[time-nuts] Temp/Humidity control systems?

[John Ackermann N8UR]

I may have the opportunity to build a small "clock room" and am 
considering whether I could make it an environmentally controlled space. 
 I'd like to learn about the options for doing this.


The space would probably be 6x8 feet or so, in a basement with one 
outside wall.


Can anyone point me to purveyors of the hardware to do something like 
this?  Because I'll have a limited time to build this, I'm looking for 
something that uses more-or-less off the shelf gear, and not a whole lot 
of custom engineering.


Thanks!
John
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