Heat pumps use between 545W and 4,286W of power depending on unit size and energy efficiency.
In this article, you’re going to learn how to calculate heat pump wattages and yearly running costs. But don’t worry! You won’t have to do a single calculation yourself.
I have calculated all the wattages and yearly running costs for the most common heat pump sizes (1-5 tons) and the most common energy efficiencies (SEER ratings between 14 and 22) for you.
So, you can just look up the numbers for your heat pump!
Quick answer: An average heat pump runs on 667W of power per ton, with a seasonal energy efficiency rating (SEER) of 18. A 3-ton unit, therefore, needs 2,000W of power and costs you $1,533 a year.
Further below, you will find the wattages of different heat pump sizes and SEER ratings, as well as their yearly running cost!
How to calculate heat pump power consumption?
Knowing the power consumption of your heat pump is important to answer several questions:
- Which generator will run a heat pump?
- Can you run a heat pump off solar panels?
- How much does a heat pump cost per year?
- How to size a heat pump?
Let’s have a look at the formula to calculate the power consumption of a heat pump. Don’t worry, we won’t dive too deep into the maths! A surface look is enough.
- Unit size (in BTU/h) = Unit size (in tons) × 12,000 BTU/h
- Total Wattage (in Watts) = Unit size (in BTU/h) ÷ SEER (in BTU/Wh)
Explanation of the heat pump total wattage formula
The first formula calculates the size of a heat pump unit in BTU/h. The most common metrics to note heat pump sizes are tons and BTU/h.
One ton is equal to 12,000BTU/h. For calculating the total wattage of a heat pump, we need the unit size denoted in BTU/h.
That’s why I included the first formula, which is nothing more than a simple unit conversion.
The second formula calculates the total wattage of a heat pump. The total wattage, as per the formula, depends only on the heat pump unit size and the SEER.
The SEER (Seasonal Energy Efficiency Rating) is a metric that determines the energy efficiency of a heat pump.
You can find the SEER on every heat pump’s specification sheet.
The SEER is defined as
SEER (in BTU/Wh) = Total Wattage (in Watts) ÷ Unit size (in BTU/h)
So, the formula to find the total wattage comes from the definition of SEER. By simply transforming the SEER definition formula, we get the total wattage formula.
I hope my explanations cleared up the formulas! If it did not click, don’t worry. The next thing that follows is an example calculation and a table with all the wattages and costs pre-calculated for you.
You don’t need to use a single brain cell.
Heat pump power consumption example calculation
What size (in BTU/h) is a 3-ton heat pump?
3 tons × 12,000 BTU/h = 36,000 BTU/h
How much power does my 3-ton heat pump consume? It has a SEER of 14.
36,000 BTU/h ÷ 14 SEER = 2,571W
That’s how to calculate your heat pump’s power consumption!
How many Watts do Heat Pumps use?
The table below lists the wattages for different energy efficiency ratings (SEER) and varying heat pump sizes.
|Unit size||14 SEER||16 SEER||18 SEER||20 SEER||22 SEER|
The power consumption of a heat pump increases with the unit size. Also, the wattage decreases for increasing efficiencies.
Per ton, an average 18 SEER heat pump consumes 667W of power. An average 3-ton heat pump uses 2,000W.
How to calculate your yearly heat pump cost?
Here’s the formula to calculate your yearly heat pump cost.
Cost (in $/year) = Unit size (in BTU/h) × Hours per year (in h) × Electricity rate (in $/kWh) ÷ SEER (in BTU/Wh) ÷ 1000 (in W/kW)
The yearly running cost of your heat pump depends on the unit size, the running hours per year, your personal electricity rate, and the SEER.
You can find your heat pump’s unit size and SEER rating in the specification. Your personal electricity rate is listed on your most recent electricity bill.
However, figuring out the hours your heat pump runs per year is not as straightforward as a simple lookup. I’ve crunched the numbers for you!
How long does a heat pump run per year?
A heat pump runs 2-3 cycles an hour. One such cycle usually lasts between 10 and 20 minutes. For average values, we can estimate 2.5 cycles per hour and 15 minutes per cycle.
This means your heat pump will run for
2.5 cycles × 15 minutes = 37.5 minutes per hour = 0.625h
0.625 × 24h a day is 15 hours a day
15h × 365 days a year = 5475 hours a year
A heat pump runs 5475 hours a year on average.
Heat pump yearly cost example calculation
Let’s look at the same 3-ton (36,000BTU/h) heat pump with a SEER of 14 which we already used in our earlier example calculation.
I assume an average electricity rate of $0.14 per kWh.
Using the formula from the previous section:
Yearly cost = 36,000BTU/h × 5475h × $0.14 ÷ 14 SEER ÷ 1000 = $1,971
To spare yourself the calculation, just look up your personal heat pump’s running cost in the next section!
How much does running a heat pump cost per year?
|Unit size||14 SEER||16 SEER||18 SEER||20 SEER||22 SEER|
An average 18 SEER 3-ton heat pump costs $1,533 to run per year. A heat pump costs between $418 and $3,285 to run per year, depending on the unit size and the energy efficiency.
For the values in the table, I assumed an average yearly running duration of 5475h. And I assumed an electricity rate of $0.14 per kWh, which is the US average.
If your yearly heat pump hours or your electricity rate vary significantly from these assumed averages, then you can use the formula to calculate your personal heat pump running cost.
Also, you can just increase the values by a fixed percentage. For example, if your electricity rate is 50% higher than the assumed value of $0.14 per kWh, you can just your heat pump running cost by 50% accordingly.
Calculating heat pump power consumption and running costs can be overwhelming. Especially, if you are new to heat pumps.
However, the heat pump power consumption and running cost tables for different heat pump unit sizes and SEER ratings should help you look up the values you are looking for.
Please note that heat pump wattages and running costs vary significantly by location.
The reason is that different states have different electricity rates and different climates.
Depending on the climate you are living in and your personal electricity rate, your cost may vary up or down.
Unfortunately, there’s not much you can do about it, except looking for a cheaper electricity provider (in case you are paying too much).
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