A heat pump uses a lot of electricity in total, because in a home that heats and cools with one, it's usually the single biggest electrical load. But it uses far less electricity for the heat it delivers than any other electric heating, since it moves heat instead of making it, producing two to four units of heat for every unit of electricity. A typical 3-ton heat pump draws about 3,000 watts at full output and uses somewhere around 10 to 30 kWh on an average heating or cooling day. Clean coils, a fresh filter and keeping the backup heat strips off as much as possible keep that number at the low end.
How Much Electricity Does a Heat Pump Use?
How much electricity a heat pump uses comes down to three things: how many watts it draws while running, how many hours it runs and how often the electric backup heat kicks in. The wattage is fairly predictable for a given size. The hours change with the weather, your thermostat settings and how well the house holds heat.
A quick way to estimate any heat pump's wattage is to divide its capacity in BTUs per hour by its EER2 rating. A 3-ton unit (36,000 BTUs) with an EER2 of 12 draws about 3,000 watts at full output. That works out to roughly 1,000 watts per ton for most modern systems running flat out.
Heat Pump Wattage by Size
System size |
Capacity |
Approx. watts at full output |
|---|---|---|
1.5 ton |
18,000 BTU |
1,500 to 1,800 |
2 ton |
24,000 BTU |
2,000 to 2,400 |
2.5 ton |
30,000 BTU |
2,500 to 3,000 |
3 ton |
36,000 BTU |
3,000 to 3,600 |
4 ton |
48,000 BTU |
4,000 to 4,800 |
5 ton |
60,000 BTU |
5,000 to 6,000 |
These figures cover the outdoor unit and indoor blower running together at full capacity. The higher end of each range fits older or lower-efficiency units and very hot or very cold days, when a heat pump has to work harder.
Variable-speed heat pumps rarely run at full output. On a mild day, a variable-speed 3-ton unit might run at 30 to 40 percent capacity and draw well under 1,500 watts, for hours at a time. That's why they use less electricity overall even though they run longer.
How Much Electricity Does a Heat Pump Use Per Day and Per Month?
Multiply the wattage by the hours of run time. A 3-ton heat pump drawing 3,000 watts for 8 hours uses 24 kWh in a day. At 15 cents per kWh, that's $3.60 for the day, or about $108 over a 30-day month of similar weather.
Real-world use swings widely. On a mild spring or fall day, the same system might use 5 to 10 kWh. During a hard freeze or a heat wave, it can run 12 to 16 hours and use 35 kWh or more. High use on the hottest and coldest days is normal. High use on a mild day is the warning sign.
To estimate your own cost to run a heat pump, find your electric rate on your bill and multiply it by your expected kWh. Many utilities also show daily usage online, which makes it easy to see how your system responds to the weather.
Why a Heat Pump Uses Less Electricity Than Other Electric Heat
A baseboard heater, space heater or electric furnace turns every unit of electricity into one unit of heat. A heat pump uses electricity to run a compressor and fans that move heat from the outdoor air into your house, and it delivers two to four units of heat per unit of electricity. That ratio is called the coefficient of performance, or COP.
In practice, a heat pump heating a home in mild winter weather uses about a third to a half of the electricity an electric furnace would use for the same warmth. The gap narrows as temperatures drop, because there's less heat in the outdoor air to move. That's when the electric backup heat strips start helping, and those strips run at a COP of 1. A heat pump that leans on its strips, or a thermostat left on emergency heat, is the fastest way to a high electric bill.
Does a Heat Pump Use More Electricity Heating or Cooling?
It depends on the climate. In homes with long, cold winters, heating usually costs more, because the heat pump works against a larger temperature difference and the backup strips run more often. In homes with long, hot summers and mild winters, cooling season usually uses more electricity. In both seasons, the heat pump uses less electricity than an electric furnace and about the same as a central air conditioner of the same efficiency.
What Drives Heat Pump Electricity Use Higher
The backup heat strips are the biggest factor. Big overnight thermostat setbacks are a common trigger, because raising the temperature 6 to 10 degrees in the morning often brings the strips on. Setbacks of 2 to 3 degrees save more on a heat pump.
Maintenance problems come next. A dirty indoor or outdoor coil, a clogged filter or blocked registers reduce airflow and force longer run times. Low refrigerant from a slow leak cuts capacity, so the system runs longer and calls the strips more often.
Sizing and ductwork matter too. An undersized heat pump runs constantly and relies on backup heat in cold weather. An oversized one short cycles, which wastes energy at every start. Leaky ducts in an attic or crawlspace lose conditioned air before it reaches a room. Correct system sizing and sealed ducts protect the efficiency you paid for.
Age plays a role as well. A heat pump that's 12 to 15 years old, especially one that has gone without regular service, typically uses noticeably more electricity than a new unit of the same size.
Heat Pump Efficiency Ratings and Power Consumption
SEER2 measures cooling efficiency across a season. The federal minimum for heat pumps is 14.3 SEER2, and an 18 SEER2 heat pump uses about 20 percent less electricity for cooling than a 14.3 SEER2 model. The SEER rating guide explains how the numbers compare.
HSPF2 measures heating efficiency across a season. The federal minimum is 7.5 HSPF2, and higher numbers mean less electricity per unit of heat. HSPF2 matters most in places with long heating seasons. EER2 measures efficiency at a single hot outdoor temperature, which is useful if your summers bring long stretches of extreme heat.
Signs Your Heat Pump Is Using Too Much Electricity
Watch for a heat pump that runs nearly nonstop in mild weather, an "Aux" light that comes on frequently when it's above freezing outside, an outdoor unit that ices over and doesn't defrost, or an electric bill that jumps compared with the same month last year. Any of these points to a problem worth having checked. If the system runs constantly but the house stays cold, see why a heat pump runs all day but the house stays cold. If the air from the vents feels cool, see heat pump blowing cold air.
How to Lower Your Heat Pump's Electricity Use
Check the filter monthly and replace it when it's dirty. Keep thermostat setbacks small, and never use emergency heat as an everyday setting. Keep the outdoor unit clear of leaves, snow and shrubs, with about two feet of open space around it. Have the system serviced once a year so the refrigerant charge, coils, electrical parts and defrost controls stay in spec. If your ducts run through an unconditioned attic or crawlspace, sealing and insulating them can make a big difference.
Get Your Heat Pump Running Efficiently
MR. HVAC is family-owned and has installed and serviced heat pumps for more than 25 years. If your heat pump is using more electricity than it should, our technicians will find out why, explain the fix in plain terms and give you the price before any work starts. Learn more about our heat pump installation and repair services, or schedule heat pump service today.
