reply to PSWired
Re: The addition saga continues
said by PSWired:As a result of your post I found an interesting study on a Fujitsu running in defrost cycle. Fujitsu behavior is as you described for your Mitsubishi.
Maybe the heat contained in the refrigerant loop, along with the heat generated by the compressor itself during normal operation, is enough to defrost the coils in his unit? The mitsubishi ductless units I have at work don't even have heat strips and they run through a defrost cycle just fine. The indoor air blower is off during defrost.
"During the reverse cycle itself, power usage is modest since the system is taking heat from a mild source and dumping it to a very cold sink (the iced-up coil in the outdoor unit). Since there is no electric resistance backup heat (as would be found in a standard residential heat pump), the overall effect of the reverse cycle is negligible. Also, there are no times where the supply air temperature dips below the return air temperature."