air source heat pump watts

How many watts does an air source heat pump use?

Your air source heat pump is likely the most energy-hungry electrical appliance in your home, and for many months, it’s almost always on! If you’re looking to cut down on your electrical bill or estimate how many solar panels you need to keep your home up and running, understanding how many watts of electricity your heat pump setup uses is one important piece of the puzzle.


Key takeaways about powering an air source heat pump


  • On average, air source heat pumps use between 545 and 4,286 watts of electricity in warm weather.
  • On average, air source heat pumps use between 1,000 and 7,500 watts of electricity in cold weather.
  • Actual energy usage depends heavily on what size heat pump you’re using.
  • It costs an average of $207 to use a heat pump for cooling for a month and $1,035 to run for a year.
  • It costs an average of $373 to use a heat pump for heating for a month and $1,865 to run for a year.
  • The best way to save on electricity is to install solar panels. Start comparing your options on the EnergySage Marketplace today.

In this article

How much electricity does an air source heat pump use?

On average, an air source heat pump uses anywhere from 545 watts to 7,500 watts of electricity, highly dependent on the size of the unit and the time of year. Most air source heat pumps use between 4 and 20 amps and about 230 volts.

Heat pumps have two separate rating systems to help determine their energy usage during different times of the year, mainly during months when they’re cooling a home versus heating a home. Below, we’ll walk through how those calculations differ.

How much electricity does an air source heat pump use in warm months?

Heat pump wattage in cooling months can be calculated using the size of the heat pump (in British Thermal Units, or BTUs), and the efficiency rating of the appliance, or its Seasonal Energy Efficiency Rating (SEER). We can use the following equation to combine a heat pump’s SEER and BTU ratings to get an average energy usage in cooling months:

Wattage per hour = BTU / SEER

Importantly, this results in a watt per hour (W/h) rating, which we’ll just use as the wattage of a heat pump for simplicity. This is useful because an air source heat pump will naturally cycle on and off over the course of an hour, so this is more of a true wattage rating we can use to determine electricity usage over time.

Using the above equation, here’s how the wattages of common heat pump sizes and SEER ratings look:

How many watts do heat pumps use in warm weather? Breakdown by size and efficiency

Heat pump sizeWattage (14 SEER)Wattage (16 SEER)Wattage (18 SEER)Wattage (20 SEER)Wattage (22 SEER)
1 ton (12,000 BTU)857 W750 W667 W600 W545 W
2 tons (24,000 BTU)1,714 W1,500 W1,333 W1,200 W1,091 W
3 tons (36,000 BTU)2,571 W2,250 W2,000 W2,000 W1,636 W
4 tons (48,000 BTU3,429 W3,000 W2,667 W2,600 W2,182 W
5 tons (60,000 BTU)4,286 W3,750 W3,333 W3,200 W2,727 W

For an average 3 ton/18 SEER-rated heat pump, which nets out to 2,000 W, here’s what your electricity use could look like:

How much electricity do air source heat pumps use in warm weather?

Air source heat pump sizeWattageLength of time poweredkWh of electricity used
3 tons (36,000 BTU)2,000 W1 hour2.0 kWh
3 tons (36,000 BTU)2,000 W1 day48 kWh
3 tons (36,000 BTU)2,000 W1 week336 kWh
3 tons (36,000 BTU)2,000 W1 month1,460 kWh
3 tons (36,000 BTU)2,000 W5 months7,300 kWh

We’re assuming that a full year’s worth of heat pump usage in warm weather is actually only 5 months because not all months of the year are warm. The key takeaway is this: for an average air source heat pump during warm weather, you’ll be looking at around 1,460 kilowatt-hours (kWh) of electricity per month during warmer months. We’ll mostly be referring to the electricity used by air source heat pumps in terms of kWh in this article. The reason is simple: your electric bill is measured in kWh, and you get charged based on the kWh of electricity you use per month!

How much electricity does an air source heat pump use in colder months?

Heat pump wattage in heating months can be calculated using the size of the heat pump (in British Thermal Units, or BTUs), and the efficiency rating of the appliance, or its Heating Seasonal Performance Factor (HSPF). We can use the following equation to combine a heat pump’s HSPF and BTU ratings to get an average energy usage in heating months:

Wattage per hour = BTU / HSPF

Importantly, this results in a W/h rating, which we’ll just use as the wattage of a heat pump for simplicity. This is useful because an air source heat pump will naturally cycle on and off over the course of an hour, so this is more of a true wattage rating we can use to determine electricity usage over time.

HSPF ratings are typically lower than SEER ratings and span a narrower overall range. Using the above equation, here’s how the wattages of common heat pump sizes and HSPF ratings look:

How many watts do heat pumps use in cold weather? Breakdown by size and efficiency

Heat pump sizeWattage (8 HSPF)Wattage (9 HSPF)Wattage (10 HSPF)Wattage (11 HSPF)Wattage (12 HSPF)
1 ton (12,000 BTU)1,500 W1,333 W1,200 W1,091 W1,000 W
2 tons (24,000 BTU)3,000 W2,667 W2,400 W2,182 W2,000 W
3 tons (36,000 BTU)4,500 W4,000 W3,600 W3,273 W3,000 W
4 tons (48,000 BTU6,000 W5,333 W4,800 W4,364 W4,000 W
5 tons (60,000 BTU)7,500 W6,667 W6,000 W5,455 W5,000 W

For an average 3 ton/10 HSPF-rated heat pump, which nets out to 3,600 W, here’s what your electricity use could look like:

How much electricity do air source heat pumps use in cold weather?

Air source heat pump sizeWattageLength of time poweredkWh of electricity used
3 tons (36,000 BTU)3,600 W1 hour3.6 kWh
3 tons (36,000 BTU)3,600 W1 day86.4 kWh
3 tons (36,000 BTU)3,600 W1 week605 kWh
3 tons (36,000 BTU)3,600 W1 month2,628 kWh
3 tons (36,000 BTU)3,600 W5 months13,140 kWh

We’re assuming that a full year’s worth of heat pump usage in cold weather is actually only 5 months, because not all months of the year are cold. The key takeaway is this: for an average air source heat pump during colder weather, you’ll be looking at around 2,628 kWh of electricity per month during cold months. 

Watts, amps, voltage, and more: what do they mean?


There are a lot of terms you can use to describe how electricity flows and is used by appliances. We’ve already mentioned most of them – here are a few definitions to keep things straight:

  • Volts (V): volts (short for voltage) are measures of electrical pressure differences. Put simply, voltage is the speed of electricity passing through a circuit.
  • Amps (A): amps (short for amperes) are a measure of electrical current. Put simply, amps are the amount of electrons (which make up electricity) flowing through a circuit.
  • Watts (W) and kilowatts (kW): multiplying volts x amps gets you watts (or wattage). Put simply, watts are the rate of electricity consumption. A kilowatt is just 1,000 watts.
  • Kilowatt-hours (kWh): lastly, kilowatt-hours are how your electric bill measures your energy usage. Simply put, kilowatt-hours are electricity consumption over time.

You can think of all of these terms like water flowing through a pipe. Voltage is the water pressure, amps are the amount of water flowing past any point, and wattage is the overall rate of water flow through the pipe.

How much does it cost to power an air source heat pump?

When you get your monthly electric bill, you only get to see the total amount you’re charged, not how much each appliance contributes to your final bill. Assuming you use your heat pump to cool your home for 5 months and heat your home for another 5 months, here’s what the cost to run an air source heat pump for warm and cold months looks like for an average 3 ton/18 SEER/10 HSPF heat pump:

Monthly costs to run an air source heat pump by state

StateAverage electricity rateCost per month (warm months)Cost per month (cold months)
California22.00 ¢ / kWh$321$578
New York20.59 ¢ / kWh$301$541
Texas12.56 ¢ / kWh$183$330
Massachusetts22.59 ¢ / kWh$330$594
Florida12.21 ¢ / kWh$178$321
Virginia12.58 ¢ / kWh$184$331
New Jersey16.20 ¢ / kWh$237$426
Maryland14.48 ¢ / kWh$211$381
Washington10.38 ¢ / kWh$152$273
US Average14.19 ¢ / kWh$207$373

Note: average electricity rates are based on October 2021 data from the U.S. Energy Information Administration (EIA).

As outlined earlier, 5 months of cooling with a heat pump will use about 7,300 kWh, and 5 months of heating will use about 13,140 kWh. In total, that’s 20,440 kWh, which will cost somewhere around $2,900 for an entire year ($1,035 for cooling, and $1,865 for heating). 

Looking to offset your electric bills (and the energy these appliances use) with solar? When you sign up (for free!) on the EnergySage Marketplace, you can compare solar quotes from high-quality, local solar installers. Make sure to keep in mind your current and future electricity usage, and talk about how that could change with your installer for the most accurate quotes.

Calculate how much energy your own air source heat pump uses

Remember that yellow Energy Saver sticker we mentioned above? If you want to know how much electricity your air source heat pump uses (or at least is supposed to use), take the estimated yearly electricity use in kWh – this is probably your best bet for an accurate number. Simply multiply this number by the average electricity rate in your area to get an estimate of how much you spend to power your air source heat pump each year. For an estimated monthly cost, divide the estimated yearly cost by 12.

How many solar panels does it take to run an air source heat pump?

Average heat pumps use up to 2,600 watts of electricity to stay powered in cold weather. On average, solar panels are rated at around 350 W, meaning you’ll need about eight panels to power most air source heat pumps. 

Importantly, heat pumps also have a starting power requirement, which can be much higher than their running wattage. Be sure to check what kind of power your heat pump needs just to turn on, because that may increase the number of solar panels you need to power it.

Frequently asked questions about powering an air source heat pump

What’s the best time to run an air source heat pump?

If you’re on a time-of-use (TOU) rate plan, you are charged different amounts for electricity throughout the day. In general, it’s cheaper to use appliances during “off-peak” hours, which are usually overnight.

What size battery do you need to back up an air source heat pump?

Most lithium-ion batteries like the Tesla Powerwall or Generac PWRcell have a power rating of 4 to 5 kW or higher, and 10+ kWh of usable capacity. Heat pumps use about 3,600 W (3.6 kW) of power at any one time – meaning most batteries will be suitable on their own for backing up your air source heat pump. A typical home battery will likely have the power rating to get your heat pump going, but you’ll need multiple batteries to fully back up a heat pump unit for a long period of time.

However, because heat pumps sometimes need a significant amount of power to start running, you may need more battery capacity in practice. Be sure to check what kind of power your heat pump needs just to turn on because that may increase the number of batteries you need to power it or the type of battery you need (e.g. one with a higher max power rating).

What are ENERGY STAR appliances?

ENERGY STAR is a U.S. government-backed system that certifies how energy-efficient appliances are. If an appliance is better than the average appliance in its category by a certain amount, it is labeled as “ENERGY STAR certified”. ENERGY STAR appliances cost less money to run, given that they are more efficient with the electricity they use.

How much money can solar panels save you?

Solar savings vary widely, and your unique savings depends on factors like electricity usage, your location, electric rates and plans, and more. In general, most homeowners can expect to save somewhere between $10,000 and $30,000 over the lifetime of a solar panel system. On average, it takes between 7 and 8 years for most homeowners who shop for solar on EnergySage to get their solar panels to pay for themselves.

Going solar is one of the most effective ways to reduce or eliminate your electric bill, and you should make sure you are getting several quotes from reputable installers before you decide to move forward. Visit the EnergySage Marketplace to get solar quotes from installers in your area and begin comparing options.


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About Jacob Marsh

Jacob is a researcher and content writer at EnergySage, where he's an expert on current issues–and new technology!–in the solar industry. With a background in environmental and geological science, Jacob brings an analytical perspective and passion for conservation to help solar shoppers make the right energy choices for their wallet and the environment. Outside of EnergySage, you can find him playing Ultimate Frisbee or learning a new, obscure board game.

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