I agree with Kurt: you need a licensed plumber in your area to advise
you, if you're trying to keep the AHJs happy .
2nd, I'm very sure you don't want an exhaust/ combustion type vent
under the array. I've had several over the years, and seen some arrays
installed over them. They can get fairly hot and put quite a bit of
steam out. I would not trust the module backing material to a
concentrated long term dose; which module is going to have a problem first?
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 9/24/2014 11:16 AM, Kurt Johnsen wrote:
Should you decide to lower your plumbing vents I have found an inside
pipe cutter to be an inexpensive and handy tool. Cut the vent and lead
off an inch above your desired pipe height and use the inside cutter
to cut the pvc pipe. Go slow and be careful to keep air space between
the pvc and lead as the lead will cut very easily.
Also I wouldn't rely on us well intentioned wrenches to make the call
on the plumbing code in your jurisdiction. Though the state plumbing
codes are usually based on the international code, there will be
differences. If you can't pull up your state plumbing code online then
ask your plumbing inspector. In Florida the minimum height above a
roof surface is 6" (904.1). As for relocating 905.2 states that "all
vent and branch vent pipes shall be so graded and connected as to
drain back to the drainage pipe by gravity". Table 710.1(1) shows that
for 1.5" pipe a slope of ¼" per foot is sufficient to handle 3
fixtures. I would take that to indicate ¼" / foot is plenty for a 1.5"
vent.
On Wed, Sep 24, 2014 at 11:20 AM, Dave Click <davecl...@fsec.ucf.edu
<mailto:davecl...@fsec.ucf.edu>> wrote:
Flipping through the '04 plumbing code I see a few slopes called
out (1/4" per 1' for fixture vents, 1" per 1' for circuit vents,
1/2" per 1' for combination drain/vent...). Fixture vents have a
maximum distance of a few feet from fixture trap to vent, but I
don't think this prevents you from then running that vent
horizontally. 916.2 states that for vents other than stack vents
or vent stacks if your vent is >40' you need to upsize the whole
vent pipe (tough to do for an existing building, of course). Stack
vents have a "maximum developed length" of 100' for a 1.5" vent
which should be enough space to get away from under the PV. I
don't see any slope requirements specifically for stack vents but
my non-plumber's eye may be missing something.
The stack vent sizing Table 916.1 appears (in part) here too and
it looks like the tables match up to a 2.5":
http://www.engineeringtoolbox.com/drainage-vents-d_1110.html
DKC
On 2014/9/24 10:19, Jason Szumlanski wrote:
I am unable to find anything in the Florida code that precludes
covering a plumbing vent. The code does require the vent to be 6"
above the roof surface I believe.
I was unable to determine if these vents need to be vertical with
no bends in the attic. Obviously you wouldn't want to create a
trap in the attic, but a couple of 45's to relocate a plumbing
vent to accommodate more PV seems like a desirable thing to do
sometimes. Does anyone know if these can be relocated, i.e. to an
adjacent roof surface?
On my own home I had a vent to deal with. I broke out my
saws-all, split the lead like a banana and peeled it back, cut
the pipe at an angle, and folded the lead back into the pipe
after applying sealant between the lead and pipe. There is a 1"
gap between the rim of the pipe and the back of the module. My
theory on this working safely is that, a) there will be far less
rainwater falling in and around this pipe with a module over it,
and b) it is about 24" from the roof ridge and there is a module
over it so there will be very little water sheeting down from
above the vent. Code notwithstanding, I felt this was a solid
method on my own home, and I have inspected it after 6 months of
Florida downpours and found no issues.
Jason Szumlanski
Fafco Solar
On Wed, Sep 24, 2014 at 6:38 AM, Bill Loesch
<solar1onl...@charter.net <mailto:solar1onl...@charter.net>> wrote:
Bruce, August, et al,
This is but one more example of confusing terminology. A
plumbing vent is not an exhaust vent!
A plumbing vent (what August calls a cold vent) is provided
to allow the sanitary drain traps (and perhaps more) to
operate properly. Without the properly functioning traps you
would have sewer gas smell and sewer gas from the plumbing
fixtures. This was commonplace when indoor plumbing was
introduced to early adopters.
An exhaust vent is another animal entirely. An exhaust vent
carries the combustion products to a suitable exterior
location for dilution with ambient air. With the advent of
power vented combustion appliances, a direct vent (one that
takes in combustion air from the outside and naturally
exhausts combustion products to the outside) is IMHO the only
responsible way to install any power vented appliance in a
freezing climate. (Power vented appliances come in both
condensing and non-condensing flavors-they can penetrate the
side wall or the roof). Originally, two separate pipes (with
two independent properly separated penetrations) was used.
That technique is still often used today. More recently
concentric vents have been introduced both for condensing and
non-condensing applications. A concentric vent can simplify
some installations by putting the exhaust pipe inside a
larger air intake pipe allowing for one, albeit larger,
penetration. As you might imagine if the exhaust flow is
hindered/diverted/redirected by an inappropriately located
solar module combustion gasses will be re-ingested into the
intake air. Not good for equipment performance. My
understanding is the power vented _appliance manufacturer_
dictates what kind of separation/clearances are needed with
their product. My guess is you find they want at least a foot
of separation between the top of the " inverted cone" and the
module. Probably not what you had in mind for an
aesthetically pleasing installation.
I hope this helps,
Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094 <tel:314%20631%201094>
On 23-Sep-14 6:54 PM, August Goers wrote:
Bruce and All, Sorry, I hit send before I had a chance to
complete my thoughts. What I meant to say was that I've
found AHJs often allow us to cover cold plumbing vents but
I've never tried or had any luck with covering hot vents
including condensing boiler PVC vents. Once again, if in
doubt you could see what the plan checker or inspector
thinks. Best, August -----Original Message----- From: August
Goers [mailto:aug...@luminalt.com] Sent: Tuesday, September
23, 2014 4:15 PM To: 'RE-wrenches' Subject: RE:
[RE-wrenches] Modules over vents Bruce, I'll send you the CA
plumbing code vent section offlist (attachment too large for
this list). The way I read the code is that you technically
can't cover any type of plumbing or hot vent. However, and
I've run into little resistance from AHJs in the Bay Area by
covering these. You might want to check in with your plan
checker. Best, August Luminalt -----Original Message-----
From: RE-wrenches
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of Bruce Leininger Sent: Tuesday, September 23, 2014 3:49 PM
To: RE-wrenches Subject: [RE-wrenches] Modules over vents Hi
all. We're designing a system on a roof that is literally
infested with plumbing, exhaust and combustion vents. The
combustion vents are PVC and none of the vents are more than
1.5' above the roof. A racking company says that we can
cover them with modules, since the modules will be at least
4' above the roof. They have not yet provided any building
code references to say that this is ok. Do any of you know
if the building code allows this? Thanks. Bruce
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