View Single Post
Old 12-30-13, 12:00 AM   #4
RB855
Helper EcoRenovator
 
RB855's Avatar
 
Join Date: Jul 2012
Location: Jacksonville, fl
Posts: 48
Thanks: 3
Thanked 14 Times in 10 Posts
Default

The defrost is time/temp based. If the controller sees the evaporator below 25*F for 90minutes, it will enter defrost. At this point, the controller turns off the evap fan, and energizes the reversing valve. It will stay in this mode until evap temperature reads 45*F, then return to normal operation. I think the max defrost time is 5 minutes (which is a very long time!). This is nearly identical to defrost cycles on your typical household heatpump, with the exception the controller exposes all the time and temperature variables.

I considered using it for a/c, but tell me if my logic is sound: In spring/summer/fall we often have outdoor temps in the 70-95 range. It will almost always be warmer outside than inside on these seasons, which are in my favor for higher evap temps. The humidity load will also do wonders. The 2-3 months we call "winter" will take a hit on efficiency, but not sure if it would be cost effective to "cascade" the unit via the whole house heatpump. That, and space inside is limited, placing the unit in a living space (or ducted). What Could work is duct the air inside during the summer, supplying conditioned fresh air to the house (hmmmm )!

Edit: I re-read your question, and it looks like your asking how well it works, not How it works. Honestly, it hasn't been cold enough to get the evap below 45*F lol. I will say that forcing defrost, the coil goes from 45 to 130*F in about 45seconds, burns off the condensate in a hurry. Once the unit has stabilized, the compressor holds a Lot of heat, and is immediately available to burn off the evap. The heat load of the water in the BPHE also offer a huge supply of instant heat to the system. Do note the capillary bypass and check valve around the TXV for this to work. Don't forget this vital part! (wana know why I have a highlimit? LOL)

Last edited by RB855; 12-30-13 at 12:09 AM..
RB855 is offline   Reply With Quote