Air to Air ASHP defrosting

[Gone West]

For those with A2A HPs, are they any better or worse than air to water ASHPs for the length and frequency of defrost cycles. When defrosting do they shut down the internal units completely.

[Radian]

1 hour ago, Gone West said:

For those with A2A HPs, are they any better or worse than air to water ASHPs for the length and frequency of defrost cycles. When defrosting do they shut down the internal units completely.

I rarely notice when defrosting is taking place so it's hard to say anything useful. It does make some interesting sounds at the indoor units though. Nothing about the external appearance of these changes (flaps stay in he same positions) but it only seems to happen when they're not blowing air around. I don't know if they stop blowing to do the defrost or wait for an opportune moment. Now you've brought this up I'll be paying more attention 😀

[JohnMo]

I think Panasonic made a big thing on how their unit doesn't switch the internal unit off during defrost.  So most likely most will pause the internal unit while defrost occurs.

[Gone West]

No danger of cold air being blown out then, sounds good 😀

[Radian]

1 hour ago, Gone West said:

No danger of cold air being blown out then, sounds good 😀

 

That's right, I've never felt any. I guess it's enough just to turn off the fan. The dehumidifier function on my Daikin Emura's must perform a similar cycle (cooling) but having just tried it, there is a little bit of cool air movement which is to be expected.

[MrMagic]

Mine (MHI) units turn the internal fan off and close the flap almost fully during a defrost cycle. +1 for weird noises during the defrost, not overly noisy, sounds a bit like a kettle boiling sometimes!