Heat pump vs air conditioner

How to read those two dials

Both dials are the lowest cooling efficiency a new split system may be sold at. In the northern states a split air conditioner may be rated as low as 13.4 SEER2 and a split heat pump no lower than 14.3. In the Southeast and Southwest the gap closes: a split AC under 45,000 Btu/h has to reach 14.3 SEER2 there too, the same floor as the heat pump. Shop above the floor and cooling efficiency becomes a model choice, not a heat-pump-or-AC choice. The SEER2 guide explains what the number measures, and the SEER2 savings calculator prices a step up from the floor.

Federal law agrees that they are one machine. The regulation defines a single product, the central air conditioner or central air-conditioning heat pump, which is “a heat pump or a cooling unit only”, and it rates every outdoor unit as a system with the indoor coil it is matched to.

Sources: 10 CFR 430.32(c)(6)(i)(A) (read 2026-09-04) · 10 CFR 430.2, definition of Central air conditioner or central air conditioning heat pump (read 2026-10-18)

One cycle, one extra valve

An air conditioner pumps heat one way: out of the indoor coil and out through the outdoor coil. A heat pump has the same compressor, coils and metering, plus a four-way reversing valve that swaps which coil is hot and which is cold. In winter the outdoor coil becomes the cold side and pulls heat out of outdoor air, and the indoor coil becomes the hot side.

That is where the heat pump picks up its extra parts and extra work: a defrost cycle for the outdoor coil, a heating rating (HSPF2, minimum 7.5 for a split system), and many more running hours a year, because the outdoor unit now runs in two seasons. The HSPF2 guide covers the heating rating and defrost.

The comparison

Not the same question as heat pump vs furnace

Our heat pump vs furnace comparison weighs two heating sources against each other on running cost and cold-night capacity. This page compares two outdoor units. If the furnace is staying either way, the choice is between an AC with a furnace and a heat pump with a furnace, and the second one is called dual fuel.

When people search heat pump vs HVAC they usually mean this page too: a heat pump against the conventional split of an AC outside and a furnace inside. In trade shorthand, heat pump vs AC.

What sits indoors

The balance point decides how much of the winter the heat pump carries alone. Work it out with the heat pump sizing calculator, and read the cold-climate heat pump guide before choosing strip heat or dual fuel for the hours below it.

Where the install price gap comes from

The two outdoor units are near relatives, so the equipment premium for a heat pump is the reversing valve, the defrost controls and the heating rating behind them. The real swings are around the box: a heat-pump thermostat and control wiring, an air handler with strip heat in an all-electric house, the circuit that strip heat needs, or the furnace control board that has to support a dual-fuel switchover. Run both options through the replacement cost calculator and ask for both on the same quote.

If the heat today is electric resistance, through an electric furnace or baseboard heaters, the heat pump is the easy call: DOE puts the electricity saving of a modern air-source heat pump at about 50% against those heaters. The federal 25C credit no longer helps either option; it covered improvements through 2025-12-31 (see the 2026 tax credit guide).

Sources: U.S. DOE, Pump Up Your Savings with Heat Pumps (2023-05-30) (read 2026-10-18) · IRS, Energy Efficient Home Improvement Credit (read 2026-09-04)

When an AC and furnace still win

Whichever unit goes outside, size it to the cooling load first, with the AC size calculator, then check that a heat pump of that size covers enough of the heating load.