How to calculate electricity usage from heat pump

[Dtkokay]

Is there a way to calculate how much electricity is used by a heat pump? I have a 126K BTU heat pump on my new pool and I’d like to get some idea for how much it’s going to cost me to run it.

The model is an Aquacal Heatwave Superquiet SQ166R. The max BTU is 126K, and the only electric stat I can find says “kW input” at 6.6.

 

[scottts]

Multiply the 6.6 kW (power) times the number of hours you expect it to run to get kWH (energy usage). Then find out from your power company how much you pay per kWH and you'll have your answer.

 

[mas985]

It depends on the COP but 6.6 kw is pretty close to nominal.

However, to estimate run time is a bit more complicated because there are several factors involved with heat transfer including if you are using a cover or not.

 

[Dtkokay]

Multiply the 6.6 kW (power) times the number of hours you expect it to run to get kWH (energy usage). Then find out from your power company how much you pay per kWH and you'll have your answer.

Thanks. I wasn’t sure if it was just that simple. I realize the run time is going to depend on a lot of variables, but I wanted at least understand how much it would cost me per hour.

 

[ajw22]

Use the Pentair Heat Pump Calculator to determine the estimated electrical cost. Select their HP around your 166K BTU size. Pentair seems to do honest calculations based on the physics and efficiencies of each type of pump and energy source.

To get the most accurate cost comparison you should change the default electric kwh, natural gas price, and propane price to actual prices in your area.

 

[SouthwestOhio]

Where does the outside air temperature factor in on the calculator?

 

[ajw22]

Where does the outside air temperature factor in on the calculator?

That affects the temperature loss form the water and how many BTUs will be required to heat the water versus lost into the cold air.

 

[SouthwestOhio]

Where does it factor in on the "heat gain" that the heat pump is able to achieve? i.e. 60° air temp vs 75° air temp.........

 

[mas985]

Everything is hidden from the user so you really don't know what their assumptions are except what is shown. I don't find it to be particularly accurate.

For electricity they come up with is half of the upper tier for me. I think they use an average but it really should be the marginal rate if you are on a tiered system.

Volume calculation is off by 20%. The don't exclude any volume for stairs.

Weather estimates can be really far off since I think they use a limited database and use nearby cities which can add quite a bit of error.

If you want a tool with a lot more visibility (and complexity), you can try my spreadsheet in my signature. It has simple tool/tab called "Heaters" and a more complex tool/tab called "Heat Txfr" which takes into account all the heat loss and heat gain components in a pool.

 

[swamprat69]

Outdoor air temperature effects both the efficiency and the BTU output of your heat pump. As the outdoor air temperature drops, so does the efficiency ( BTU output per KW input ) and also the total BTU output as compared to a higher outdoor air temperature. That is why if you heat your home with a heat pump in a colder climate you normally need some form of auxiliary heat when the outdoor temperature falls below 32 degrees F, as the heat pump dropping BTU output cannot keep up with the increased heat loss due to the greater temperature difference between indoor and outdoor air. That being said, even at 0 degrees F or below a heat pump is still more efficient than either electric resistance or fossil fuel ( gas/propane etc.) heat.

 

[mas985]

A HP may be more efficient but it may not always be more cost effective. Depends on the pricing of electricity vs NG.