Heat Pump - Spec advise please (urgent)

[steveb21]

I am getting offered a heat pump and would like to know if it would be suitable for my pool.
Energy prices in the UK have gone crazy and are expected to go up again considerably next year aswell. I only use my pool in the summer months,

My pool dimensions are listed in my sig. The current owner used the pump with a inground pool of 38x16ft.

Spec is:


Am i correct in my calculations that it requires 4.7kW per hour to run? Therefore calcs as:

 

[PoolGate]

Heat pumps in the US are rated in BTUs. A large one is 150k BTUs. A small one maybe 50k BTUs. Your pool is fairly small (by US standards). That seems to be in the upper end of the range for that line. You can never go too big on a pool heater.

Found a calculator KW to BTU so that heater is 75k BTUs. If the price is right, it will work for you. If you can find larger, go for it!

Kilowatts (kW) to BTU/hr conversion calculator

Kilowatts (kW) to BTU per hour, power conversion calculator. Enter the power in kilowatts and press the Convert button:

www.rapidtables.com

 

[steveb21]

Heat pumps in the US are rated in BTUs. A large one is 150k BTUs. A small one maybe 50k BTUs. Your pool is fairly small (by US standards). That seems to be in the upper end of the range for that line. You can never go too big on a pool heater.

Found a calculator KW to BTU so that heater is 75k BTUs. If the price is right, it will work for you. If you can find larger, go for it!

Kilowatts (kW) to BTU/hr conversion calculator

Kilowatts (kW) to BTU per hour, power conversion calculator. Enter the power in kilowatts and press the Convert button:

www.rapidtables.com

Many thanks for the quick response.
Unit is 4 years old and is £500 (been told it was £3500 new)

How can I work out how long it will take to increase temp by 1 degree on a summers day (Uk summer day average temp is 20 degrees!)

 

[flynwill]

How can I work out how long it will take to increase temp by 1 degree on a summers day (Uk summer day average temp is 20 degrees!)

Since you don't use British Thermal Units any more on your side of pond, I'll do the calculation in metric units.

45k Liters is 45,000 kg. Heat capacity of water is 1.16 Watt-hours per kg per degree C.
According to the table above that heatpump will produce 17.5kW of heat to the pool = 17,500 Watt-hour per hour
So 17,500 / ( 1.16 * 45,000 ) = 0.334 Degree C per hour heat rise.

 

[dfwnoob]

Isn't it a bit ironic we use BTU and the UK doesn't? Lol

 

[PoolGate]

Since you don't use British Thermal Units any more on your side of pond, I'll do the calculation in metric units.

45k Liters is 45,000 kg. Heat capacity of water is 1.16 Watt-hours per kg per degree C.
According to the table above that heatpump will produce 17.5kW of heat to the pool = 17,500 Watt-hour per hour
So 17,500 / ( 1.16 * 45,000 ) = 0.334 Degree C per hour heat rise.

Note - 17.5 is cooling capacity. That heater has 22 heating capacity.

 

[flynwill]

Note - 17.5 is cooling capacity. That heater has 22 heating capacity.

Ah, good catch, revising the calculation:
22,000/ ( 1.16 * 45,000 ) = 0.42 Degree C per hour heat rise.

So a bit better. It is also important to note the operating conditions for that spec which is 27C air and 25C water. If the air is substantially cooler than the water the available capacity will drop. And also the heat losses will rise, so on a cool day the actual heating time might be quite a bit longer than this calculation would lead you to expect.

 

[PoolGate]

One more note heat pumps work quite a bit better the more humid it is. I don't think they work at all in desert climates.