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Heat Pump vs Air Conditioner
Quick answer: A heat pump and a central air conditioner cool a home the same way, but a heat pump has a reversing valve and controls that let it also heat. If you are replacing an AC and have a furnace, a heat pump can take over most heating while the furnace provides backup. Cooling efficiency is compared with SEER2.
The key difference
An air conditioner moves heat from inside to outside only. A heat pump can run that cycle in reverse, moving heat from outside to inside in winter. The outdoor units look similar. The heat pump adds a reversing valve, defrost controls and components rated for winter operation.
Cost differences
A heat pump typically costs somewhat more than a comparable air conditioner. That extra cost buys heating capacity that can reduce furnace or boiler use. Whether it pays back depends on fuel prices, climate and the heat pump's efficiency. Use the operating cost calculator to compare.
When an AC still makes sense
- Very low gas prices and a newer high-efficiency furnace.
- Very short heating seasons, where heating is minimal.
- Electrical service that cannot support a heat pump plus backup without an expensive upgrade.
When a heat pump makes sense
- You heat with oil, propane or electric resistance.
- Your furnace or boiler is aging.
- You want to reduce combustion appliances.
- Incentives favour heat pumps in your area; see US or Canada.
Dual-fuel setups
Pairing a heat pump with an existing furnace gives a dual-fuel system. The heat pump heats in mild and moderate weather; the furnace takes over below a set outdoor temperature. See heat pump vs furnace.
Efficiency ratings
Both are rated for cooling with SEER2 and EER2. Heat pumps also have HSPF2 for heating. See HSPF and SEER explained.
Worked example
Figures below are illustrative examples (2026-10-29), not quotes or guarantees.
A homeowner replacing a 3-ton AC gets quotes of $7,800 for an AC and $9,300 for a heat pump. With propane at a high price, the operating cost calculator shows the heat pump could save about $600 a year on heating compared with the propane furnace, giving a simple payback on the $1,500 difference of about 2.5 years. With cheap natural gas, savings might be much smaller.
What changes in the outdoor unit
Inside a heat pump's outdoor cabinet you will find a reversing valve, a defrost control board, and sometimes a crankcase heater and accumulator for winter operation. These parts let the coil act as an evaporator in winter, absorbing heat. The indoor coil becomes the condenser, releasing heat into the air handler's airflow. Because the outdoor unit works year-round, it accumulates more running hours than an AC, which matters for lifespan and maintenance. See heat pump lifespan.
Indoor equipment
A heat pump typically pairs with either an air handler (with optional electric backup) or with a furnace in a dual-fuel setup. An AC pairs with a furnace coil or air handler. If your current furnace is relatively new, the heat pump coil can sit on top of it, much like an AC coil. The installer must make sure the controls and thermostat are compatible.
Sizing considerations
When replacing an AC with a heat pump, the cooling size may be fine, but in cold climates the heating load is often higher than the cooling load. A contractor may suggest a slightly larger variable-speed unit to cover more heating hours, or keep the original size and rely on the furnace below a certain temperature. Use the heat pump size calculator for a rough heating range and compare it with your AC's tonnage via the BTU to tons calculator.
Running cost in summer
In cooling mode, a heat pump and an AC with the same SEER2 use about the same electricity. Choosing a higher SEER2 heat pump than your old AC can therefore lower summer bills as well as winter fuel bills.
Running cost in winter
Winter savings depend on your existing heating fuel and prices. Against oil, propane or resistance heat, heat pumps usually save. Against natural gas, results vary; dual fuel lets you use whichever is cheaper at each outdoor temperature.
Noise and placement
Heat pump outdoor units run in winter, so placement near bedrooms or neighbours matters year-round. Defrost cycles make occasional whooshing noises. Check sound ratings and local bylaws.
Electrical
Many heat pumps use similar circuits to ACs of the same size, but adding electric backup strips can require larger circuits. Your electrician should verify.
Questions to ask contractors
- Can the heat pump cover my heating at the design temperature, or will the furnace run below a set point?
- What switchover temperature do you recommend and why?
- Is my thermostat compatible?
- What are the SEER2, EER2 and HSPF2 ratings for the matched system?
Decision summary
If your furnace is in good shape and you mainly want cooling, an AC can make sense with cheap gas. If you want lower heating costs, fewer combustion hours or incentive eligibility, a heat pump is often the better replacement. Compare scenarios in the operating cost calculator.
When a heat pump replaces only the AC
If you have a working furnace and are replacing an old air conditioner, a heat pump can take its place at a modest extra cost and provide heat in mild weather, with the furnace covering cold days. This dual-fuel setup needs a compatible thermostat and a switchover temperature chosen with your installer.
Running cost in summer
In cooling mode a heat pump and an air conditioner with the same SEER2 rating use about the same electricity. The difference shows up in winter, when the heat pump can replace some or all fuel use.
FAQ
Do heat pumps cool as well as ACs?
Yes, comparable models cool equally.
Can I convert my AC into a heat pump?
No; the outdoor unit is different.
Will a heat pump raise my electric bill?
Yes, but it lowers fuel bills; compare totals.
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