Pool heat pumps

[dpmiller]

Possibly a silly question but...

 

Other than the maximum temp being capped at 40c instead of 60c and the lack of control for a 3-way valve, what are the differences between pool heat and home heating ASHPs?

[ProDave]

I suspect because they have a large volume of water to heat, they are "all or nothing" heaters so probably direct on line start no inverters, no ability to modulate to low power.  Not a good idea for a house heating system.

[Jeremy Harris]

Nothing really.  They may well have a heat exchanger that's optimised fro higher flow rates and a higher flow to return temperature differential, but without looking at one and playing with it it would be hard to be definitive about how it might behave running something like UFH.  One point worth noting is that pool ASHPs don't modulate, they are designed to run flat out all the time.  That means they probably aren't going to be as quiet or efficient running something like UFH as an inverter driven unit.

[Stones]

I looked at them briefly and the issue was operating air temperature range, most of the (cheaper) pool units wouldn't operate below 5C ambient according to the spec sheets.

[ProDave]

1 hour ago, Stones said:

I looked at them briefly and the issue was operating air temperature range, most of the (cheaper) pool units wouldn't operate below 5C ambient according to the spec sheets.

Could that mean they don't have the reverse cycle defrost function, so they would indeed be useless for winter heating?

[Jeremy Harris]

They don't have a 4 way valve usually, so can't reverse cycle.  My guess is that they probably just turn off and wait if icing is detected, which may well be why there is a +5°C minimum outside temperature operating restriction.

[ragg987]

Not really answering the question, but my Hitachi (domestic) ASHP has a separate circuit for swimming pool. The standard logic for priority is DHW, then space heating and finally swimming pool heating. Includes ability to connect to a pool thermostat, valve and circulating pump to control it.

 

I have used the capability to heat a 90l buffer (that is another story), and it works well. From observation, the modulation behaviour is different from DHW and space heating - it tends to run at a higher rate.