Heat pump vs furnace + AC.

Your furnace dies in the middle of January. Or it's going to, sometime this year, probably. You called three HVAC contractors for quotes. Two of them wrote you a bid for a new gas furnace plus a matching AC unit, the same two-machine setup most houses have had since the 1980s. The third one mentioned heat pumps in passing, then spent more time explaining them than recommending them.

Now you're on the internet trying to figure out whether the heat pump people have a point, or whether the contractors you trust with your money know something the internet doesn't.

Short version: in most of the country in 2026, the heat pump people are right. Operating cost has dropped below gas-furnace economics in five of seven US climate zones, federal tax credits of up to $2,000 close most of what's left of the installation gap, and cold-climate models from Mitsubishi, Fujitsu, and Daikin now keep houses warm at minus fifteen degrees. What matters is which climate zone you live in, how cheap your natural gas is, and whether your electrical panel can handle the load. That's what this guide walks through, with actual numbers.

How a heat pump actually works

A heat pump isn't a new invention. It's an air conditioner running in reverse. The same refrigeration cycle that moves heat out of your house in summer can be pointed the other way in winter, pulling heat from outdoor air and delivering it indoors. That sounds implausible when the outdoor air is 20°F, but the physics work fine: even freezing air contains thermal energy relative to refrigerant evaporating at -10°F.

That 4-to-1 ratio is the entire reason heat pumps keep winning against gas furnaces. Furnaces convert chemical energy into heat with some losses. Heat pumps move energy that already exists. For most outdoor temperatures most of the year, moving heat takes far less energy than creating it.

Why climate zone is the deciding factor

Every article you'll read online tells you "it depends." It mostly depends on one thing: outdoor air temperature during heating season. A heat pump in Houston is operating at COP 3.5 nearly every winter night. A heat pump in International Falls, Minnesota is operating at COP 1.8 on the coldest mornings. The efficiency advantage shrinks as the outdoor air gets colder.

The IECC splits the US into seven climate zones based on heating degree days. Zone 1 is South Florida. Zone 7 is northern Minnesota, the Upper Peninsula, parts of interior Alaska. Your zone is the single best predictor of whether a heat pump or a furnace-plus-AC will cost less to run.

The pattern in that chart is what you need to remember:

Zones 1 through 4 (most of the US, including everything south of a line from Richmond through St. Louis to San Francisco). Heat pumps save meaningful money, usually $300 to $500 per year. The house runs on electricity with no gas line required. There's essentially no argument for a gas furnace anymore.

Zone 5 (Chicago, Denver, Philadelphia, Boston). Operating costs are within $100 per year either way. The decision comes down to installed cost and which fuel you'd rather depend on. Federal tax credits usually make the heat pump the rational pick.

Zones 6 and 7 (Minneapolis, Fargo, northern Vermont, Alaska). Natural gas still wins on operating cost, especially where gas is cheap. But cold-climate heat pumps and dual-fuel hybrids close the gap substantially. Neither answer is wrong in these zones; context matters.

The cold-climate question

For 30 years, the standard critique of heat pumps was that they stop working when it gets really cold. It was true until about 2018. Standard heat pumps do lose efficiency below 30°F and typically can't produce useful heat below 15°F without expensive electric resistance backup kicking in.

That's the old product. Modern cold-climate heat pumps are different machines. Inverter-driven variable-speed compressors and enhanced refrigerant circuits let them maintain a COP above 1.8 down to -5°F and still deliver usable heat at -15°F. The benchmark brands are Mitsubishi Hyper-Heat (FH series), Fujitsu XLTH, and Daikin Aurora, though most major manufacturers now offer a cold-climate line.

The spec that matters is HSPF2 (Heating Seasonal Performance Factor, 2023 test standard). Federal minimum is 7.7. Zone 5 performance needs HSPF2 at or above 9.0. For zones 6 and 7, look for 10.0 or higher, which typically means cold-climate certified under the NEEP (Northeast Energy Efficiency Partnerships) Cold Climate Air-Source Heat Pump Specification.

The tax credit accelerant

The Inflation Reduction Act extended and expanded the 25C Residential Energy Efficient Home Improvement Tax Credit through 2032. For heat pumps that meet efficiency thresholds (SEER2 ≥ 16 and HSPF2 ≥ 9 for split systems), it covers 30% of installation cost, capped at $2,000 per year. Most installed heat pump systems above $7,000 hit the cap.

Separately, the HEEHRA rebate program (also IRA-funded) provides point-of-sale rebates up to $8,000 for income-qualified households, rolling out state by state. Check the DOE's program directory for current availability. In many states these stack with the 25C credit, which means some buyers pay nothing out of pocket for equipment costing $10,000+.

The furnace + AC option qualifies for the credit too, but only the furnace portion, and only if it's 95% AFUE or better. That's a $600 credit against a $10,500 install. The heat pump's $2,000 credit closes most of the gap, and in many real bids it reverses it.

When heat pumps are the wrong answer

The case against is narrow but real. Four situations where a gas furnace plus AC still makes legitimate sense:

Very cold climate plus cheap natural gas. In parts of Minnesota, North Dakota, and Wisconsin where natural gas delivers below $1.00/therm, a 95% AFUE furnace still beats even a cold-climate heat pump on annual operating cost. The gap is typically $300 to $600 per year, which compounds to $4,500 to $9,000 over a 15-year equipment life. That's enough to justify the furnace, especially if your existing gas service is already installed.

An electrical panel that can't handle it. A 3-ton heat pump draws up to 30 amps at 240V. Most houses built before 1990 have 100-amp service, and many are already near capacity with modern appliance loads. Upgrading to a 200-amp panel runs $2,000 to $4,000 and takes a day. That cost has to be added to the heat pump bid. Sometimes it flips the math.

Ductwork sized for a furnace. Heat pump supply air is cooler than furnace supply air (typically 95–105°F vs 125–140°F), which means more volume is needed to deliver the same heat. Undersized ducts cause cold rooms and comfort complaints. Proper duct modifications can add $1,500 to $5,000 to a heat pump install. Most contractors will skip the duct assessment unless you ask.

Emergency replacement in February. If your AC died yesterday and your furnace is already 15 years old, the time to plan a heat pump conversion isn't now. Replace what failed with like equipment, then plan a heat pump conversion for 5 to 8 years from now when the furnace wants replacing. Rushed heat pump installs rarely go well.

Before you sign the contract

Once you've decided on heat pump vs furnace + AC, the next risk is a bad install. These are the four things to verify with any contractor before signing:

1. Ask for a Manual J load calculation. Not square-foot rules of thumb. Not what your old equipment was sized for. An actual ACCA Manual J calculation takes 1–2 hours and accounts for insulation, windows, orientation, air leakage, and local design temperature. Contractors who refuse or hand-wave this are the ones who oversize your equipment. Oversized heat pumps short-cycle, wear out fast, and make rooms feel clammy.
2. Verify the outdoor unit will clear snow. In any zone that gets snow, the outdoor unit needs to be mounted 12–18 inches above grade on a stand or pad. It also needs to sit clear of anywhere roof snow slides off. Installations with the outdoor unit on the ground at a snow drop get buried and lose capacity every storm.
3. Check electrical panel capacity. Get the contractor to calculate your current load (or do it yourself from the panel spec and plug-in appliance tags). If you're above 80 amps on a 100-amp service, budget for a panel upgrade before you budget for the heat pump.
4. Specify the model number. "A 3-ton heat pump" is not a spec. "Mitsubishi MSZ-FS18NA with SUZ-KA18NAHZ outdoor unit, HSPF2 10.5" is a spec. Put the exact model on the contract. Substitutions happen all the time, and a SEER2 16 unit doesn't qualify for the tax credit where a SEER2 14 doesn't.

Run a gut check on the install bid with the Tallyard heat pump calculator to see if the tonnage the contractor quoted matches the load math. A properly sized heat pump is usually smaller than a contractor's first guess. Oversizing is the single most common mistake in residential HVAC.