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Heat Pump vs Furnace Cost
COP explained, the 2.95 break-even against gas, cold-climate performance, and the price sensitivity that flips the answer.
Filed October 25, 2026 · figures checked against 2026 sources
What COP actually means
A furnace makes heat by burning fuel. A heat pump moves heat from outside to inside, spending electricity to do the moving rather than the making. The Coefficient of Performance, COP, is the ratio: a COP of 3.0 means three units of heat delivered for each unit of electricity consumed. That is not a violation of physics; the extra two units come from the outdoor air, not from the electricity. It is also why the comparison with a furnace is not apples to apples: a furnace's efficiency tops out below 100%, while a heat pump's COP routinely runs above 300% in mild weather, because moving heat is cheaper than making it.
The catch is that COP is not a constant. It falls as outdoor temperatures fall, because there is less heat outside to move and the machine works harder to move it. A pump rated at COP 4.0 in 47 degree weather may run at COP 2.0 below freezing, and on the coldest nights it hands over to backup resistance heat, which runs at COP 1.0, the most expensive heat in the house. Any comparison that uses a single brochure COP for the whole season is therefore suspect. The honest number is the seasonal average COP, and it depends on your climate more than on the brand on the box.
The season math at default prices
At the calculator's defaults, 1,800 square feet, moderate climate, average insulation, electricity at 17 cents per kilowatt-hour, the heat pump at COP 3.0 costs $677.23 for the season. The gas furnace at $1.35 per therm costs $688.12. Resistance heat costs $2,031.70. The pump beats gas by $10.89, which is a rounding error dressed as a victory, and beats resistance heat by $1,354.47, which is a transformation. Both statements are true, and which one matters depends on what you heat with now. For a resistance-heated home, the heat pump case is overwhelming. For a gas-heated home, the case is thin on running cost alone, and has to rest on other grounds: carbon, cooling in summer, or a gas system that needs replacing anyway.
The break-even COP against gas at these prices is 2.95, derived in the fuel comparison article from the cost per million BTU: $49.82 for resistance electricity divided by $16.88 for gas. Run the sensitivity and the fragility of the pump's win becomes clear. At COP 2.0, the season costs $1,015.85, and gas wins by $327.73. At COP 4.0, the season costs $507.92, and the pump wins by $180.20. The pump's case lives or dies on the seasonal COP your climate actually delivers, and a cold-climate home that averages COP 2.5 through the winter is a gas house on running cost, whatever the brochure promised.
The electricity price flips the answer
Prices flip the answer as surely as climate does. At 25 cents per kilowatt-hour, with everything else at defaults, the heat pump season rises to $995.93, and gas at $688.12 wins by $307.81. At $1.00 per therm for gas, the gas season falls to $509.72, and nothing electric comes close. The two prices that decide the comparison are the electricity price and the gas price in your town, not the national averages in this article. A household in a cheap-gas, expensive-electricity utility territory is a gas household, and a household in a cheap-hydro, expensive-gas territory is a heat-pump household, and no national article can settle which one you are. Run the calculator at your prices; that is the entire point of it.
The cold-climate catch, honestly stated
Cold-climate heat pumps are much better than they were a decade ago, and the categorical claim that they do not work in the cold is outdated. Modern cold-climate units hold useful capacity well below freezing. But capacity is not efficiency: a pump that still heats at 5 degrees may be doing so at COP 1.5, and the backup resistance heat that covers the coldest hours runs at COP 1.0. A home in a cold climate can therefore own a good pump and still post a mediocre seasonal COP, and the season average is what the bill measures. The dual-fuel setup is the pragmatic answer for cold climates: the pump carries the mild and moderate weather, where its COP is high, and the gas or oil burner takes the deep cold, where combustion wins. The calculator's fuel strip lets you price that split by running the pump row for the mild months and the furnace row for the cold ones, though a full dual-fuel model would need monthly degree-days.
When to switch, and when to wait
Switch when your current system is dying anyway, because the incremental cost of a pump over a like-for-like furnace replacement is the honest comparison, not the full installed price against zero. Switch when you heat with resistance electricity or oil, because the running-cost saving is large: $1,354.47 against resistance on the model house, $916.11 against oil. Switch when your electricity is cheap and your climate is mild or moderate, because the seasonal COP will clear 2.95 with room to spare. Wait when your gas system is young and your gas is cheap, because $10.89 a season does not repay an early replacement. Wait when your electricity is expensive, because 25 cent power erases the pump's edge. And in every case, get the seasonal COP estimate for your climate from the installer in writing, not the mild-weather rating from the brochure, and check it against the 2.95 break-even at your prices before signing.
The heat pump is not a moral choice or a fashion choice. It is an arithmetic choice with three inputs: your electricity price, your gas price, and your seasonal COP. At 17 cents, $1.35, and COP 3.0, the pump wins by a whisker against gas and by a mile against resistance heat. Change any one input and the answer can flip, which is why the comparison belongs in a calculator, not in a slogan.
Heat pump questions
- Is a heat pump cheaper than a gas furnace?
- At the defaults, barely: $677.23 against $688.12 a season, a $10.89 edge. Against resistance heat the edge is $1,354.47. The break-even COP against gas is 2.95 at 17 cents per kilowatt-hour and $1.35 per therm.
- Do heat pumps work in cold climates?
- Modern cold-climate units heat well below freezing, but efficiency falls with temperature, and backup resistance heat covers the coldest hours. Seasonal COP, not the brochure rating, decides the bill. Dual-fuel setups pair the pump with a furnace for deep cold.
- What electricity price makes gas cheaper than a heat pump?
- At the defaults, 25 cents per kilowatt-hour lifts the pump season to $995.93 against $688.12 for gas. Cheap electricity favors the pump; expensive electricity favors gas.