View Full Version : Hissing ASHP

24-02-2017, 01:37 PM
Recently my ASHP has started to hiss when it starts up and expels warm moist air (my glasses steamed up) before running cold after a few minutes.

I've never noticed it hiss or expel warm air - is this normal or is something going wrong with the heat pump?

The Viking
24-02-2017, 02:41 PM
Assuming you are standing in front of the outdoor unit then it sounds like it is going through a defrost period.

Further assuming that it is still providing hot water and heating as desired then this is perfectly normal.


27-02-2017, 01:51 PM
Thanks Viking - that's a relief!