AC vs heat pump: which one fits your home?
Outdoors they look nearly identical. The difference is what they can do in winter.
An air conditioner only cools. A heat pump cools in summer and heats in winter. The outdoor units look almost the same, which is why people confuse them.
The real question is what you pair with it for winter heat. That decides which one makes sense.
How each one works
Both move heat rather than make it. An AC pulls heat out of your house and dumps it outside. A heat pump does the same in summer, then reverses the flow in winter to pull heat from outdoor air into your home. A part called the reversing valve makes that switch possible.
AC vs heat pump at a glance
| Feature | Air conditioner | Heat pump |
|---|---|---|
| Cooling | Yes | Yes |
| Heating | No, needs a furnace or boiler | Yes |
| Reversing valve | No | Yes |
| Best climate | Hot summers, cold winters with a furnace | Mild to moderate winters, or cold with backup heat |
| Fuel for winter heat | Gas, oil or electric furnace | Electricity |
When an AC plus furnace makes sense
If you already own a working gas furnace and only the cooling side has failed, a matching AC is usually the simpler swap. It also suits homes where winters are long and bitterly cold and gas is the cheaper fuel locally. Your local utility rates decide that, so check them rather than guess.
When a heat pump is the better pick
If you have no gas line, or you want one system for the whole year, a heat pump is hard to beat. It fits mild and moderate winters well. In colder regions, modern cold-climate models plus backup heat can still cover the season.
The question most people skip: sizing and ducts
Either system performs badly if it is the wrong size or the ducts leak. A bigger unit is not a better unit, because oversized equipment cycles on and off and wears out sooner. Ask for a load calculation, not a guess based on square footage.
How to tell which one you have
Check the thermostat first. If it has an EM or AUX setting, you have a heat pump. Then look at the outdoor unit's data plate. The model label usually says air conditioner or heat pump. When in doubt, ask a licensed HVAC technician.
What not to do
- Do not open the outdoor unit. A capacitor inside can hold a dangerous charge even when the power is off.
- Do not add or check refrigerant. It requires federal EPA Section 608 certification.
- Skip the DIY wiring. Electrical work is for a licensed technician.
Frequently asked questions
Can a heat pump replace my AC?
Yes. A heat pump cools just like an AC, and it also heats. A licensed HVAC technician can confirm your ducts and electrical service suit it.
Do heat pumps work in cold weather?
They do, within limits. Many models need backup heat on the coldest days, and cold-climate models handle more of the season.
How can I tell if my outdoor unit is an AC or a heat pump?
Look for EM or AUX on the thermostat and check the model label on the outdoor unit. If you are unsure, ask a licensed technician.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- ENERGY STAR. Air-Source Heat Pumps
- ENERGY STAR. Energy Savings at Home: Heating & Cooling