Working out ASHP efficiency at a certain temperature.

[kindai]

Hopefully some of you big brains here have some experience of this.

I have an ASHP heating a pond.

I know what a number of values are, but wondering if from those we can work out (even if approximate) some specific values.

What I have:

Air Temp: 26 c
Water Temp: 26 c
Power in: 0.73kw
Power out: 4.25kw
Cop: 11.60

Air Temp: 15 c
Water Temp: 26 c
Power in: 0.75kw
Power out: 3.15kw
Cop: 6.75

Air Temp: -15 c
Water Temp: 26 c
Power in: 0.71kw
Power out: 1.40kw
Cop: 3.22


From that is it possible to work out or made a general indication of the following:

Air Temp: 0 c
Water Temp: 18 c
Power in: 0.75kw
Power out: ? kw
Cop: ?

 

[PermaChanged]

Why's the output of the heat pump greater at an air temp of 26c than it is at an air temp of -15c, to get the same water temp?

 

[Reuben klang]

Why's the output of the heat pump greater at an air temp of 26c then it is at an air temp of -15c, to get the same water temp?

Youre over thinking it, latent heat is easier to absorb at higher temps.

Think of it like taking some water at -15°c (be an ice block) and taking it up to 50°c would take way more energy than 26°c > 50°c

You’re taking that similar heat difference from the air and putting it into the heat exchanger to heat the water up so the output is much higher.

 

[Coran]

Why's the output of the heat pump greater at an air temp of 26c than it is at an air temp of -15c, to get the same water temp?

It’s looking at power, rather than overall energy for the day. The unit probably operates at a set power but may run for far less time when at higher outdoor temps (when it can extract more power from the surrounding air than at lower air temps).

 

[jpaul]

cop simulator suggest the answer is 542

COP comparator – John Cantor Heat Pumps

Estimating the COP of a heat pump using Carnot COP

heatpumps.co.uk

10% of power for the fans/pump % seems to cause other data points to match,
doesn't the ashp have some kind of spec sheet ?