Whenever you have a power outage, every heat pump owner wants to know one thing:
“How much electricity does a heat pump use?”
Knowing how many watts does a heat pump use is useful in a number of cases, including:
- How much does it cost to run a heat pump? (They are considered very energy-efficient)
- How big a generator do you need to run a heat pump? (Start-up wattage is key here)
- Will a solar panel system be able to provide enough electricity to power a heat pump?
How much electricity does a heat pump use?
Heat pumps use anywhere from 802 watts to 5,102 watts (that is between 0,802 kWh to 5.102 kWh per hour), costing anywhere from $0.10 to $0.98 per hour to run. Starting wattage (relevant for generator size) can be 3 times higher still; between 2,406 W and 15,306 W.
This is quite a large spectrum. In order to figure out your much electricity does your heat pump use, you have to consider 3 main factors that the heat pump wattage depends on:
- Size or capacity (tonnage); primary factor. The bigger the heat pump, the more power it will need to run. Example: 4-ton heat pump will use more electricity than a 2-ton unit.
- Energy efficiency (SEER rating); primary factor. The more efficient the heat pump, the fewer watts it will require to run. Example: 14 SEER 3 ton heat pumps draws 3,061 watts. 22 SEER 3 ton heat pump draws 2,406 watts; that’s quite a big difference.
- Type of heat pump; secondary factor. In general, same size ground-source heat pump requires less electricity to run than an air-source heat pump (due to higher SEER rating).
Now, determining exactly how many watts does a heat pump require to run isn’t all that easy. If you crack open the specification sheet of a heat pump, you will rarely see something like “Max. Wattage = 3,000W”.
What you will always find in the specs sheet, however, is the SEER rating. We can use SEER rating to determine how many watts and amps do you need to run such a heat pump. First of all, we will look at how to get to the wattage of any heat pump via SEER rating.
Further on, you will also find how many watts do 1-5 ton heat pumps use (summarized in a table).
How To Check How Many Watts Does A Heat Pumps Use?
As you know, wattage is not labeled on the heat pump spec sheet. Fortunately, SEER rating (Seasonal Energy Efficiency Rating) is. We can calculate the total wattage heat pump uses from SEER rating using these two equations:
EER = −0.02 × SEER² + 1.12 × SEER (Equation 1)
Total Wattage = Capacity (In BTUs) ÷ EER (Equation 2)
In short, we convert SEER to EER (Equation 1), and we use the calculated EER to calculate the total wattage of a heat pump (Equation 2). It might sound a bit complex but it’s quite easy; you just insert the SEER rating in Equation 1 and go from there.
Here’s an example of what we get:
A 2-ton heat pump (24,000 BTU) has a 20 SEER rating. How many watts does it run on? Let’s calculate that:
EER at 20 SEER = −0.02 × 20² + 1.12 × 20 = 14.4
Total Wattage (2-ton, 20 SEER) = 24,000 BTU ÷ 14.4 = 1,667 Watts
Using these two equations, we can calculate how much power does any heat pump use. We did just that and summarized the results in this table:
How Many Watts Do Heat Pumps Use?
|Heat Pump Size:||Wattage (14 SEER):||Wattage (16 SEER):||Wattage (18 SEER):||Wattage (20 SEER):||Wattage (22 SEER):|
|1 ton (12,000 BTU)||1,020 W||938 W||877 W||833 W||802 W|
|1.5 ton (18,000 BTU)||1,531 W||1,406 W||1,316 W||1,250 W||1,203 W|
|2 ton (24,000 BTU)||2,041 W||1,875 W||1,754 W||1,667 W||1,604 W|
|2.5 ton (30,000 BTU)||2,551 W||2,344 W||2,193 W||2,083 W||2,005 W|
|3 ton (36,000 BTU)||3,061 W||2,813 W||2,632 W||2,500 W||2,406 W|
|3.5 ton (42,000 BTU)||3,571 W||3,281 W||3,070 W||2,917 W||2,807 W|
|4 ton (48,000 BTU)||4,082 W||3,750 W||3,509 W||3,333 W||3,209 W|
|4.5 ton (54,000 BTU)||4,592 W||4,219 W||3,947 W||3,750 W||3,610 W|
|5 ton (60,000 BTU)||5,102 W||4,688 W||4,386 W||4,167 W||4,011 W|
Using this table, you can answer pretty much any question regarding how many watts does your heat pump run on.
Example: Let’s say you have a 16 SEER 3 ton unit. How many watts does it require to run? Just check the table and you will see that such a 3-ton unit runs on 2,813 W.
This is quite valuable information if you’re looking at what wattage generator you need to run a 3-ton unit.
We hope this helps. If you haven’t found the answer in the article above, you can give it as a comment below and we’ll try to help you out with the calculation.