Re: [MBZ] OT: Heat Pump Demand Defrost?
Thanks for that link. I saw that thread but had not read all of it until after I saw it again in your post. It was most helpful. At the end of that thread they talk about the 47D01U-843 board, which is the one I'm considering. It costs a bit more but won't need a relay or other modifications, just some configuring. The pinout is different from the stock Carrier board so I'm thinking about making "gender bender" cables to go between with the stock Carrier connectors and the new board to make it easy to stick the stock board back in (warranty reasons). > -Original Message- > From: Mitch Haley via Mercedes > Sent: Thursday, January 17, 2019 9:20 AM > > I think Rheem = Emerson (don't know) and if I'm right you'd need to modify > the printed circuit or install an external relay to make it work. > The Rheems go for about $60 on Amazon. > > With Rheem to Carrier I'm sure you'd have to reverse the power to the > reversing valve. > Almost everybody uses reversing valves that default to heat mode when not > powered. > Rheem, last I knew, used reversing valves that are normally cooling. > > I'd go to that DIY discussion board I linked earlier and see if Beenthere is > still > around for specific advice for your new unit. > Or I can see if I have his email address on my other computer. > > This is what I should have done, adding a relay would have been simpler than > tracking down the sensors that didn't come with the board I bought and I > would have saved about $60. > https://www.amazon.com/Upgraded-Rheem-Defrost-Control-47-21517- > 14/dp/B00DS7AWYG > > ___ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
If I had a conventional air handler I'd agree. But my Unico air handler is a "high velocity" design that's supposed to output higher temp air through 2 inch diameter ducts that mixes with room air. The new heat pump is a 3 ton 14 SEER Carrier unit (very simple). The existing (2005 vintage) air handler is rated at 3-3.5 tons and only the leaky coil (and TXV) were replaced. I am at the low end of the spec CFM range but I am within the spec air flow range. The blower speed is not adjustable but it has a restrictor plate to throttle air flow. This house was built in 1850 something and there was no good way to retrofit full size ducts so we went with this oddball high velocity system. It actually works well except in one room where the mini ducts are too long. The old R22 heat pump which was replaced was also 3 tons. > -Original Message- > From: Mercedes [mailto:mercedes-boun...@okiebenz.com] On Behalf Of > Mitch Haley via Mercedes > Sent: Thursday, January 17, 2019 10:02 AM > To: Mercedes Discussion List > Cc: Mitch Haley > Subject: Re: [MBZ] OT: Heat Pump Demand Defrost? > > Sounds like your brand new system is too big for the available airflow. > Refrigeration units are more efficient at lower temperature rise. > If you're seeing more than a 20-25° rise from return to supply temp you need > more air. > (like 68° thermostat setting and 88° supply outlet temps) It might be because > the installer didn't set the blower speed right or it might be because your > ducts > are too small. > I'd check the static pressure (pressure in the supply duct minus pressure > going > into the air handler) and find out if you're overworking the new blower. If > you > have the install book it should have some pressure info, but IIRC anything > over > one inch is considered bad. > > Luckily my house had a 100,000 btu furnace in it, so although the ducts were > marginal for the original design they're oversized for the 46k furnace and 1.5 > ton AC I put in. > > > On January 16, 2019 at 11:40 PM Scott Ritchey via Mercedes > wrote: > > > > My other system is a new (week-old) Carrier R410 heat pump so I'm a little > reluctant to start hacking it just yet. That new R410a Carrier heat pump > with a > Unico air handler really puts out heat; I get 110+ degree source air when > it's 50 > degrees outside and still 100+ degree source air when it's 25-30 degrees > outside. > > ___ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
Sounds like your brand new system is too big for the available airflow. Refrigeration units are more efficient at lower temperature rise. If you're seeing more than a 20-25° rise from return to supply temp you need more air. (like 68° thermostat setting and 88° supply outlet temps) It might be because the installer didn't set the blower speed right or it might be because your ducts are too small. I'd check the static pressure (pressure in the supply duct minus pressure going into the air handler) and find out if you're overworking the new blower. If you have the install book it should have some pressure info, but IIRC anything over one inch is considered bad. Luckily my house had a 100,000 btu furnace in it, so although the ducts were marginal for the original design they're oversized for the 46k furnace and 1.5 ton AC I put in. > On January 16, 2019 at 11:40 PM Scott Ritchey via Mercedes > wrote: > > My other system is a new (week-old) Carrier R410 heat pump so I'm a little > reluctant to start hacking it just yet. That new R410a Carrier heat pump > with a Unico air handler really puts out heat; I get 110+ degree source air > when it's 50 degrees outside and still 100+ degree source air when it's 25-30 > degrees outside. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
I think Rheem = Emerson (don't know) and if I'm right you'd need to modify the printed circuit or install an external relay to make it work. The Rheems go for about $60 on Amazon. With Rheem to Carrier I'm sure you'd have to reverse the power to the reversing valve. Almost everybody uses reversing valves that default to heat mode when not powered. Rheem, last I knew, used reversing valves that are normally cooling. I'd go to that DIY discussion board I linked earlier and see if Beenthere is still around for specific advice for your new unit. Or I can see if I have his email address on my other computer. This is what I should have done, adding a relay would have been simpler than tracking down the sensors that didn't come with the board I bought and I would have saved about $60. https://www.amazon.com/Upgraded-Rheem-Defrost-Control-47-21517-14/dp/B00DS7AWYG ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
Thanks for the input. I've been looking at a retrofit board by Emerson: https://climate.emerson.com/documents/presentations-en-us-4848412.pdf That kit is about $100 and I still need to see if it will fit. I have one older (well past warranty) R22 system that I may try first. It has always been a weak performer and prone to icing. so little ventured. My other system is a new (week-old) Carrier R410 heat pump so I'm a little reluctant to start hacking it just yet. That new R410a Carrier heat pump with a Unico air handler really puts out heat; I get 110+ degree source air when it's 50 degrees outside and still 100+ degree source air when it's 25-30 degrees outside. We had freezing rain last weekend and the new heat pump was TOTALLY iced up because the installer failed to connect one wire. That's when I became more interested this topic. Thanks again. Scott > -Original Message- > From: Mercedes [mailto:mercedes-boun...@okiebenz.com] On Behalf Of > Mitch Haley via Mercedes > Sent: Wednesday, January 16, 2019 4:53 PM > To: Mercedes Discussion List > Cc: Mitch Haley > Subject: Re: [MBZ] OT: Heat Pump Demand Defrost? > > I put a Nordyne board in my Goodman about five years ago, because the timed > defrost drove me nuts. 90% of the time it defrosted when it didn't need it, > and > in humid/foggy conditions it turned into a giant sno-cone before the time was > up. > > The Rheem boards come with the sensors, my Nordyne board didn't, at least > not from the eBay seller I got it from. The problem with Rheem is their > reversing valves work backwards from everybody else, so if you want to put a > Rheem demand defrost control board in a heat pump that isn't Rheem/Ruud, > you have to modify the board or add relays to make it work properly. > > You need the demand control board, the ambient temperature sensor, and > the coil temperature sensor. With demand defrost, it defrosts when the > difference between air temp and coil temp gets too big. > > Now that propane is down around $1.20 again, the easy way to avoid defrosts > is to set my switchover temp to 35-40° so it never frosts up in the first > place. It > still defrosts every 4 1/2 hours of running time, supposedly to return oil to > the > compressor. > > Mitch. > > ___ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
https://www.diychatroom.com/f17/retrofit-demand-defrost-goodman-clpt42-129571/ ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Heat Pump Demand Defrost?
I put a Nordyne board in my Goodman about five years ago, because the timed defrost drove me nuts. 90% of the time it defrosted when it didn't need it, and in humid/foggy conditions it turned into a giant sno-cone before the time was up. The Rheem boards come with the sensors, my Nordyne board didn't, at least not from the eBay seller I got it from. The problem with Rheem is their reversing valves work backwards from everybody else, so if you want to put a Rheem demand defrost control board in a heat pump that isn't Rheem/Ruud, you have to modify the board or add relays to make it work properly. You need the demand control board, the ambient temperature sensor, and the coil temperature sensor. With demand defrost, it defrosts when the difference between air temp and coil temp gets too big. Now that propane is down around $1.20 again, the easy way to avoid defrosts is to set my switchover temp to 35-40° so it never frosts up in the first place. It still defrosts every 4 1/2 hours of running time, supposedly to return oil to the compressor. Mitch. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] OT: Heat Pump Demand Defrost?
I wonder if any of the august sages here gave experience or objective data on the value of retrofitting demand defrost on a heat pump that came with time/temperature defrost. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
