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 <mercedes@okiebenz.com> > Cc: Mitch Haley <mi...@mitchellhaley.com> > 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
