What is a heat pump?
Updated August 2026
A heat pump is an electric system that both heats and cools a house by moving heat from one place to another instead of burning fuel to make it. In summer it behaves exactly like a central air conditioner, dumping indoor heat outside. In winter a reversing valve flips the refrigerant flow, so the same machine pulls heat out of cold outdoor air and delivers it inside. Moving heat beats creating it: a heat pump commonly returns 2 to 4 units of heat for every unit of electricity it draws, where a resistance heater returns exactly 1.
Where it is
Look for two boxes. Outside sits a unit that resembles an AC condenser, because it is one with a reversing valve and a defrost control added. Inside, an air handler holds the coil, the blower, and usually a bank of electric backup heat strips. Three tells separate a heat pump from plain central air: the outdoor unit runs in January, the thermostat has an EMERGENCY HEAT or AUX setting, and the data plate lists an HSPF2 rating next to SEER2. The ductless version of the same technology is called a mini-split.
What it does
In heating mode the outdoor coil runs colder than the outdoor air, so frost builds on it. The system reverses itself for a few minutes now and then to melt that frost, which is why a heat pump steams like a kettle on a damp morning and blows cool air briefly: normal behavior, not a breakdown. Capacity falls as the temperature drops. Older single-stage units start leaning on backup heat strips around 30 to 35 degrees, and those strips cost 2 to 3 times more per unit of heat delivered. Cold-climate inverter models hold useful output at 0 degrees and below, which is why they now sell in Maine and Minnesota. Three failures are worth knowing: a slow refrigerant leak (weak heating and cooling both), a stuck reversing valve (it cools when you asked for heat), and a dead defrost board that turns the outdoor coil into a block of ice.
Maintenance
A heat pump works year-round, so it earns about twice the attention an air conditioner gets: professional service in both spring and fall rather than one annual visit. Between visits, change filters every 30 to 90 days, keep 18 to 24 inches of clear space around the outdoor unit, rinse the outdoor coil each spring, and in snow country mount the unit on a stand high enough that drifts never bury the coil. Intervals are laid out in how often to service a heat pump and how often to clean heat pump coils.
What it costs to replace
A replacement heat pump runs $5,000–12,000 installed for a whole-home system, or $12,000–20,000 for a cold-climate inverter system with a new air handler.
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Frequently asked questions
Do heat pumps still get a federal tax credit in 2026?
No. The 25C Energy Efficient Home Improvement Credit, worth 30% of a qualifying heat pump up to $2,000, ended for equipment placed in service after December 31, 2025. What is left in 2026 is local money: utility rebates and state programs, which commonly run $300–2,000 per system and more for income-qualified households. Ask the installer to quote the job with and without those rebates, since filing the paperwork is usually their job, not yours.
Are heat pumps cheaper to run than a gas furnace?
It depends on your two utility rates. Across much of the South and the Pacific Northwest, where winters are mild and electricity is moderate, the heat pump wins outright. In cold states with cheap natural gas, a furnace can still be cheaper during the coldest weeks, which is why dual-fuel systems pair the two and switch over somewhere around 25 to 35 degrees. Compare your cost per therm against your cost per kilowatt-hour before assuming either answer.
How long does a heat pump last?
Plan on 12 to 15 years, a couple of years shorter than a comparable air conditioner because the same equipment runs in both seasons instead of four or five months a year. Coastal salt air trims it further. Twice-yearly service, clean coils, and filters changed on time are what carry a unit to the top of that range. The full curve is in how long a heat pump lasts and how often to replace a heat pump.