Heat Pump vs Air Conditioner: What Is Different, What It Costs, and Which to Buy

A heat pump and a central air conditioner are the same machine in cooling mode; the heat pump adds a reversing valve and a few controls so it can run backward and heat your home in winter. That extra hardware typically adds about $1,000–$3,000 to the installed price, and it is worth paying whenever you heat with electricity, oil or propane, or your furnace is nearing the end of its life. AC-only still makes sense if you have a newer gas furnace and cheap gas. This comparison is based on manufacturer specifications, AHRI and ENERGY STAR listings, published cost data and owner feedback rather than hands-on testing.

At a glance

The mechanical difference

Both systems move heat with a refrigerant loop: a compressor, an outdoor coil, an indoor coil and an expansion device. In summer both absorb heat at the indoor coil and dump it outdoors. A heat pump adds a reversing valve, a four-way valve mounted on the compressor discharge line, that swaps the roles of the two coils so the outdoor coil absorbs heat from winter air and the indoor coil releases it into your ductwork. Because the outdoor coil gets cold enough to frost, a heat pump also carries a defrost control that briefly runs the system in cooling mode to melt ice, an accumulator to protect the compressor from liquid refrigerant during that switch, and metering devices that work in both flow directions. That is essentially the entire parts difference. Our how heat pumps work explainer has diagrams.

Two consequences follow. First, in cooling mode a heat pump performs exactly like an AC of the same tier: same compressor, same coils, same SEER2. Second, a heat pump runs in winter too, so it accumulates roughly twice the operating hours, which is why its expected lifespan is a few years shorter.

Efficiency

For cooling, there is no meaningful efficiency difference. Both are rated by SEER2 and EER2 under the same test procedure, and manufacturers build matching heat pump and AC models on the same platform: single-stage units around 14.3–16 SEER2, two-stage around 16–18, and variable-speed units from 18 to the mid-20s (ductless units go higher). Our SEER2, HSPF2 and COP explainer covers the ratings.

For heating, the heat pump’s advantage over electric resistance is large. A heat pump with a seasonal COP of 3 delivers three units of heat per unit of electricity, so it uses about a third of the electricity of baseboard heaters, an electric furnace or the strip heat inside an air handler. At $0.17 per kWh, 100,000 BTU costs about $4.98 with resistance heat and about $1.66 with a COP-3 heat pump. Against oil at $4 per gallon in an 85% furnace (about $3.40 per 100,000 BTU) or propane at $3 per gallon in a 95% furnace (about $3.45), the heat pump saves roughly half. Against natural gas the math is closer and depends on local prices; see our heat pump vs furnace comparison for the full break-even calculation.

Heating and cold-weather performance

An air conditioner has no cold-weather performance to speak of; whatever heats your home in winter does that job. A heat pump’s heating capacity and efficiency fall as outdoor temperatures drop. Standard-tier heat pumps deliver useful heat down to around 25–30°F efficiently and lean on backup strip heat below their balance point, which is fine in climate zones 1–4. Cold-climate models hold 100% of rated capacity at 5°F and keep operating to -13°F or lower, which makes a single all-electric system viable in zones 5–7; our best heat pumps for cold climates guide lists them.

If you already have a gas furnace and are replacing only the AC, a heat pump can be installed on top of the furnace as a dual-fuel system. The thermostat runs the heat pump in fall and spring and on mild winter days, when its COP is highest, and hands off to the furnace below a set outdoor temperature. This is the most common way homeowners with gas heat get value from a heat pump without giving up their furnace.

Noise

In cooling mode the two are equally loud, because they share compressors, fans and cabinets; sound ratings for a given tier run from the high 60s dB(A) for single-stage units down to the low 50s for variable-speed models at minimum speed. A heat pump adds two sounds an AC never makes: the “whoosh” of the reversing valve switching during defrost, and a brief rush of steam from the outdoor unit as ice melts. Both are normal and last less than a minute. Our heat pump noise guide explains what is normal and what is not.

Reliability and warranty

Manufacturers offer the same warranties on matching heat pump and AC models, typically 10 years on parts with registration and 10–12 years on the compressor from brands such as Trane. Reliability is similar per operating hour, but a heat pump runs more hours, so it will generally need service or replacement sooner: plan on 12–15 years versus 15–20 for an AC. The reversing valve is one added failure point; a stuck or leaking valve typically costs several hundred dollars to about $1,500 to replace, and it is covered under the parts warranty for the first decade. Defrost boards and outdoor sensors are minor additional items. Annual maintenance is the same for both, plus keeping the outdoor unit clear of snow and ice in winter; see our maintenance checklist.

Cost

Typical installed prices (2026, before incentives) with existing ductwork and a compatible air handler or furnace:

The premium is smaller than most homeowners expect because the indoor equipment, ductwork connections, electrical work and labor are the same. What tips the math is what you are replacing on the heating side. If your furnace is 15 years old or more, a heat pump plus a basic air handler is usually cheaper than a new AC plus a new furnace. If your heat is electric, oil or propane, the heating savings alone typically repay the premium in one to three winters. The federal 25C tax credit ended for systems placed in service after December 31, 2025, but many state and utility programs still pay $500–$3,000 or more for a heat pump and nothing for an AC, which can erase the premium outright; check current status with our incentives update. Our 2026 heat pump cost guide and cost calculator help you put local numbers on it.

Which should you choose

When a heat pump wins

• You heat with electric baseboards, an electric furnace, oil or propane.
• Your gas furnace is 15 years old or more and would need replacing soon anyway.
• You live in climate zone 1–4, where a standard heat pump handles most of the winter without backup.
• You want to add a dual-fuel heat pump to a working gas furnace and cut shoulder-season gas use.
• Your utility or state offers heat pump rebates that close the price gap.
• Your home has no gas service and you want to avoid running a new line.

When AC-only makes sense

• You have a high-efficiency gas furnace less than about ten years old and natural gas costs well under $1.25 per therm.
• You live in climate zone 6 or 7, gas is cheap, and you do not plan to run a heat pump for heating anyway.
• The budget is tight, you are selling within a few years, or the property is a rental where you pay for equipment and tenants pay utilities.
• Your electrical panel cannot support the heat pump’s backup strip heat without a costly upgrade.

If you are on the fence, our is a heat pump right for my home guide walks through climate, fuel and duct questions, and our best budget heat pumps list shows how small the premium can be.

Our recommendation

If you are replacing a central air conditioner, buy a heat pump unless you have a specific reason not to. For the price of a modest upgrade you get a system that cools identically and can also heat your home for a fraction of the cost of electric, oil or propane heat, and that qualifies for rebates an AC never will. The clearest exception is a home with a newer high-efficiency gas furnace and cheap gas, where an AC-only replacement saves money up front and a dual-fuel heat pump is an optional refinement rather than a necessity. Whichever you choose, insist on a load calculation and an AHRI-matched system; our best heat pumps rankings are a good place to start comparing models.