My furnace just died. Should I replace it with a heat pump?
The short version
- Running cost is the part this page can answer completely. Against a 95% AFUE gas furnace, a heat pump costs less to run in 4 of 45 states, about the same in 8, and more in 33.
- Against propane, heating oil or electric resistance, the heat pump wins comfortably in almost every state. If that is what died, the running cost case is strong and the decision is mostly about capital.
- This page does not price the equipment. That is the other half of the decision and this site has no first-hand data on it. What is offered here is the half that can be computed, plus the questions to take to a contractor.
- The single most useful thing you can do in a hurry is get more than one quote and ask each for a load calculation, because the most expensive mistake in an emergency replacement is oversizing.
You have days, not months, and most of the advice you will find was written for someone with time.
What this page can and cannot tell you
What running cost can settle is a question worth settling: whether switching makes your monthly bill better or worse, and by roughly how much. That is the part where a lot of the marketing is simply wrong, and it is the part you can check before anyone visits.
Start with what actually died
The answer depends far more on the fuel you were burning than on anything about heat pumps.
| What died | Running cost verdict | What it means for the decision |
|---|---|---|
| Natural gas furnace | Mixed. Cheaper in 4 states, dearer in 33 | The hard case. Check your state before assuming either way. |
| Propane furnace | Heat pump wins almost everywhere | Strong running cost case. The gap is usually large. |
| Oil boiler or furnace | Heat pump wins almost everywhere | Strong running cost case, and you stop buying oil. See the comparison. |
| Electric resistance | Heat pump wins everywhere | The one case with no argument. Roughly 2.6 times more heat per kWh. |
If what died was anything other than a natural gas furnace, the running cost question is close to settled and your remaining decision is about capital, timing and what the installer can actually do in the time available.
If it was a gas furnace, this is the hard case
Natural gas is the one fuel that regularly beats a heat pump on running cost, and where you live decides it. At December 2025 to February 2026 EIA prices, with a cold climate heat pump at HSPF2 11.0 against a 95% AFUE furnace:
- Cheaper to run with a heat pump in 4 states: Arkansas, Hawaii, North Carolina, Washington.
- Too close to call in 8: Alabama, Arizona, Georgia, Missouri, Oregon, South Carolina, Texas, Virginia. Inside 10%, which is less than fuel prices move between seasons.
- More expensive to run in 33 states. The full list is on the state index.
If you are in the third group, that is not automatically an argument for another furnace. It is an argument for looking at dual fuel, which keeps the furnace for the coldest hours and runs the heat pump for the much larger number of mild ones. It is also worth remembering that a heat pump replaces your air conditioner, which a furnace does not.
The expensive mistake people make in a hurry
Emergency replacements get oversized. There is no time for a load calculation, so the replacement is specified to match the old unit, and the old unit was very likely oversized too. [ASHRAE CCC23-37]
This site paid for a Manual J on a house where two contractors had offered confident equipment recommendations without one. [ACCA Manual J] The measured load came in well under what had been proposed. The whole exchange is written up here, and the short version is that the two confident answers were about twenty degrees apart on balance point and neither was close.
What to ask, when you have one phone call
- "What is the design heating load, and how did you calculate it?" A number with a method behind it beats a number without one.
- "What is this unit's COP at 17F and at 5F?" Not HSPF2, which is a season average and hides cold weather behaviour. The submittal has the table. [AHRI 210/240-2023]
- "What is the balance point, and how much backup heat do you expect?" This is the input that moves running cost most, and a small share of heat from resistance strips costs a large share of efficiency.
- "Is my electrical panel adequate, and is that in the quote?" A panel upgrade is a common surprise.
- "What rebates apply, and do you handle the paperwork?"
- "If this is dual fuel, what crossover temperature will you set, and on what prices?" There is a right answer and it is computable.
Who this page is for, and who it is not
It is for you if your heating has failed or is about to, you are choosing between like-for-like replacement and a heat pump, and you want the running cost half of that decision settled with real prices rather than a brochure.
It is not for you if you are planning a replacement months ahead. You have time to do this properly: start at what it costs per month, get a load calculation done without deadline pressure, and gather quotes across a season rather than a weekend.
It is also not for you if your existing bill is the problem rather than the equipment. If the system still runs but the bill is alarming, that is a diagnostic question, not a replacement one.
Common questions
Is it cheaper to replace a broken furnace with a heat pump?
On running cost it depends on the fuel and the state. Against a 95% AFUE gas furnace a heat pump costs less to run in 4 of 45 states and more in 33. Against propane, oil or electric resistance it costs less in almost every state. On purchase and installation cost this site holds no data and makes no claim.
Can I get a heat pump installed in an emergency?
Often yes, but availability of specific cold climate models is the usual constraint rather than labour. This is where emergency replacements go wrong: the unit that is in stock gets installed, and it may not be the unit with the COP curve your climate needs. If you can heat the house another way for a week, that week is worth a lot.
Should I just replace like for like to save time?
It is the fastest path and sometimes the right one. It is worth ten minutes to check your state page first, because if you heat with propane or oil the running cost gap is usually large enough to change the calculation even after allowing for a higher install cost.
What if my furnace died and I heat with oil?
That is the strongest running cost case on this site short of electric resistance. Heating oil delivers heat at roughly two and a half times the cost of natural gas, and a heat pump beats it in almost every state. See the oil comparison for the state by state figures.
Does a heat pump work if my ducts were sized for a furnace?
Sometimes, and this is a real risk in a rushed replacement. A heat pump delivers a larger volume of cooler air than a furnace, so ductwork sized for furnace supply temperatures can be undersized for the same heat output. Ask specifically whether the existing ducts were checked, not just whether they exist.
How this was checked
The state counts on this page are computed from EIA residential prices for December 2025 to February 2026, at a cold climate heat pump of HSPF2 11.0 with 10% of heat from electric resistance backup, against a 95% AFUE gas furnace. They are recomputed on every build from the same data behind the state pages, so this page cannot drift out of step with them.
The oversizing and load calculation material is first-hand: three contractors were asked the same question and a Manual J was commissioned on the house in question. The write up is here, including where this site's own assumptions turned out to be wrong.
What this page does not cover
Equipment and installation cost. The largest number in this decision, and the one this site has no first-hand data on. Get written quotes.
Rebates, tax credits and financing. These vary by state, utility and year, and they routinely move the answer.
Electrical capacity, ductwork and refrigerant line routing. Physical constraints that only a site visit can settle.
Comfort, noise and how the house feels. Real considerations that no running cost model captures.
Emissions. A separate question with a frequently different answer.
References
- U.S. Energy Information Administration. Electricity Data Browser, retail sales and average price by state and sector, monthly. Series accessed through the EIA Open Data API v2.
- U.S. Energy Information Administration. Natural Gas Prices, residential price by state, monthly, dollars per thousand cubic feet. Series accessed through the EIA Open Data API v2.
- Air Conditioning Contractors of America. Manual J: Residential Load Calculation, the standard method for sizing residential heating and cooling equipment.
- ASHRAE Cold Climate Conference 2023 paper on heat pump oversizing and seasonal efficiency, cited by the Indiana homeowner in support of deliberate oversizing for a non cold climate unit.
- Air-Conditioning, Heating, and Refrigeration Institute. AHRI Standard 210/240-2023: Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment. This standard defines the M1 test procedure and the HSPF2 metric.
- U.S. Department of Energy, Building Technologies Office (2021). Residential Cold Climate Heat Pump Technology Challenge Specification.
- U.S. Environmental Protection Agency. ENERGY STAR Program Requirements for Central Air Conditioners and Heat Pumps, cold climate heat pump criteria requiring a COP above 1.75 at 5°F.
Related reading
Check your own state before you call anyone
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