Heat Pumps vs. Furnaces
In the D.C. area's mixed-humid climate, a modern heat pump can carry most or all of the heating season and doubles as your air conditioner, while a gas furnace delivers steady heat on the coldest nights but needs a separate AC for summer. Neither is automatically better here; the right choice depends on your gas and electric rates, your ductwork, the age of your current equipment, and whether a dual-fuel system that uses both makes sense.
What climate are we heating for?
Washington, DC, Montgomery and Prince George's counties in Maryland, and Northern Virginia jurisdictions including Fairfax, Arlington, Alexandria and Prince William all fall in climate zone 4A under the International Energy Conservation Code. The Department of Energy's Building America program calls this a mixed-humid climate: more than 20 inches of rain a year, about 5,400 heating degree days or fewer, and average monthly winter temperatures that drop below 45°F.
In plain terms, that means real winters and humid summers. You need dependable heat and serious cooling, which is exactly where the two systems differ.
How does each system heat a home?
Heat pump
A heat pump does not burn fuel. As DOE puts it, it transfers heat rather than converting it from a fuel. In winter it pulls heat from outdoor air and moves it inside with refrigerant; in summer, a reversing valve sends the heat the other way and the same equipment cools the house. DOE says today's heat pumps can cut electricity use for heating by up to 75% compared with electric resistance heat such as baseboard heaters or electric furnaces.
Gas furnace
A furnace burns natural gas or propane and blows household air across a heat exchanger and out through the ducts. It heats only, so it is paired with a central air conditioner for cooling. Because it burns fuel, it needs proper venting, and the CPSC recommends carbon monoxide alarms on every level of the home and outside sleeping areas.
What do SEER2, HSPF2 and AFUE mean?
The two systems are rated differently, so their numbers cannot be compared directly.
- HSPF2 (heat pumps, heating): the total heat delivered over a typical heating season divided by the electricity used. Higher is better.
- SEER2 (heat pumps and AC, cooling): the heat removed over a typical cooling season divided by the electricity used. Higher is better.
- AFUE (furnaces): DOE defines it as the heat actually delivered to your house compared with the fuel supplied to the furnace. An 80% AFUE furnace turns 80% of its fuel into heat for the home.
The "2" versions of the heat pump ratings are the updated test procedures that federal minimums have used since January 1, 2023.
| Equipment | Current federal minimum | ENERGY STAR level |
|---|---|---|
| Split-system heat pump | 14.3 SEER2, 7.5 HSPF2 | 15.2 SEER2, 7.8 HSPF2, 11.0 EER2 or higher |
| Packaged heat pump | 13.4 SEER2, 6.7 HSPF2 | 15.2 SEER2, 7.2 HSPF2, 10.0 EER2 or higher |
| Non-weatherized gas furnace | 80% AFUE | Not covered in this guide |
The furnace minimum is in flux. DOE finalized a rule requiring 95% AFUE for non-weatherized gas furnaces made on or after December 18, 2028, a level that effectively requires condensing technology. A federal appeals court upheld the rule in 2025. On June 8, 2026, the Supreme Court vacated that ruling and sent the case back, after DOE told the Court it now agrees with the gas-industry challengers. DOE is also weighing a petition to delay compliance to at least January 1, 2030, and had not made a final decision as of this writing. Ask your contractor where it stands when you shop.
How do heat pumps handle cold weather?
A heat pump's output and efficiency drop as the outdoor temperature falls, because there is less heat in the air to move. Newer equipment has narrowed that gap. DOE says cold-climate heat pumps are designed to perform at temperatures as low as 5°F, and ENERGY STAR's cold-climate label requires a coefficient of performance of at least 1.75 at 5°F and at least 70% of rated heating capacity at that temperature.
For the coldest hours, heat pumps rely on backup heat. In ducted systems this is commonly electric resistance strips in the indoor air handler, which thermostats often label "auxiliary" or "emergency" heat. ENERGY STAR notes that a cold-climate heat pump keeps working below 5°F, but pairing it with a backup source heats the home most efficiently when temperatures drop further.
Frost on the outdoor coil is also normal in winter. The system periodically reverses to defrost it, and DOE recommends a heat pump with demand-defrost control, which reduces both defrost cycles and backup heat use.
What is a dual-fuel system?
A dual-fuel, or hybrid, system pairs an electric heat pump with a gas furnace. DOE describes it this way: the heat pump handles most of the heating in milder weather, and the furnace takes over during colder temperatures. A thermostat or control switches between them, usually based on outdoor temperature, at a point your installer sets.
ENERGY STAR suggests considering a heat pump if you have a relatively new furnace with an older central AC. Instead of replacing the AC with another AC, a heat pump in its place gives you efficient heating for most of the season while the furnace covers the coldest days.
Example: Say your 15-year-old central air conditioner fails in the spring, but your gas furnace is only six years old. Replacing the AC with a heat pump instead gives you cooling plus efficient heat for most of the winter, while the furnace takes over on the coldest days. That is the dual-fuel setup ENERGY STAR suggests considering in exactly this situation.
What affects the cost to run each one?
There is no single answer for every home, and any estimate should use your own utility rates. These are the factors that move the number:
- Your electric and gas rates. A heat pump runs on electricity; a furnace mainly on gas.
- Equipment efficiency. HSPF2 for the heat pump, AFUE for the furnace.
- How often backup strips run. Electric resistance backup uses far more electricity than the heat pump for the same amount of heat.
- Ducts and insulation. Leaky ducts and a drafty house raise the cost of any system.
- What you would replace anyway. If your AC is near the end of its life, a heat pump replaces it as part of the same purchase.
DOE notes that if your heating or cooling system is more than 15 years old, new equipment can lower your energy bills. ENERGY STAR suggests considering replacement when a heat pump or air conditioner is more than 10 years old, or a furnace more than 15.
How does maintenance compare?
Both systems need clean filters; DOE recommends cleaning or replacing them monthly during peak seasons. A heat pump runs in both summer and winter, so keep the outdoor unit clear of leaves, snow and debris, and have it checked ahead of each season. DOE says technicians should leak-check the refrigerant system at each service call. A furnace needs its burner, flame sensor and venting inspected by a professional, along with working carbon monoxide alarms.
Refrigerant and gas work are never DIY jobs. If your system is acting up, our guides cover a heat pump not cooling in summer, a furnace blowing cold air and a furnace short cycling.
Heat pump vs. furnace at a glance
| Factor | Heat pump | Gas furnace |
|---|---|---|
| How it heats | Moves outdoor heat inside with refrigerant | Burns gas and blows air over a heat exchanger |
| Cooling | Yes, same system | No, needs a separate central AC |
| Rating | HSPF2 (heat), SEER2 (cool) | AFUE |
| Coldest days | Output drops; backup heat fills the gap | Output does not depend on outdoor temperature |
| Fuel | Electricity | Natural gas or propane, plus electricity for the blower |
| Safety extras | No combustion in the heat pump itself | Venting and carbon monoxide alarms |
| Upkeep | Filters, outdoor coil, pre-season checks | Filters, burner and venting inspection |
When does each make sense?
A heat pump tends to fit when you need to replace both heating and cooling, you have no gas service or want to move away from it, or your home is reasonably well sealed. A furnace with central AC tends to fit when you already have gas, your furnace has years left, and you prefer combustion heat on the coldest nights. Dual fuel fits when your furnace is fairly new but the AC is failing.
Appliance Surgeon repairs HVAC systems across D.C., Northern Virginia and nearby Maryland, seven days a week with no evening or weekend surcharge. See HVAC repair for details.
Sources
- energy.gov: DOE Building America: D.C., Montgomery and Prince George's counties are IECC 4A, mixed-humid; definition of mixed-humid climate
- openei.org: Fairfax, Arlington, Alexandria and Prince William (VA) counties listed in climate zone 4A
- energy.gov: heat pumps transfer heat; up to 75% less electricity than resistance heat; cold-climate heat pumps perform to 5°F; dual-fuel description
- energy.gov: transfers rather than converts heat; HSPF and SEER definitions; reversing valve for cooling and defrost; demand-defrost control reduces supplementary energy use; refrigerant leak-check at each service call
- energystar.gov: cold-climate units keep working below 5°F but are most efficient paired with backup; dual-fuel flexibility; consider a heat pump with a newer furnace and older AC; clean filters
- energystar.gov: ENERGY STAR SEER2/HSPF2/EER2 levels; cold-climate COP 1.75 and 70% capacity at 5°F
- ecfr.gov: federal minimums from January 1, 2023: split heat pumps 14.3 SEER2 / 7.5 HSPF2; packaged 13.4 SEER2 / 6.7 HSPF2
- federalregister.gov: 95% AFUE for non-weatherized gas furnaces from December 18, 2028; current standard 80% AFUE since 2015
- federalregister.gov: AGA, APGA and NPGA petition to move compliance to at least January 1, 2030; 95% effectively requires condensing furnaces; pending litigation
- achrnews.com: June 8, 2026 Supreme Court action vacating the appeals court decision and remanding the case
- energy.gov: AFUE definition; clean or replace filters monthly in peak season; systems over 15 years old; professional inspection
- cpsc.gov: CO alarms on every level of the home and outside sleeping areas
- contractingbusiness.com: June 8, 2026: Supreme Court vacated the D.C. Circuit ruling upholding the 95% standard after DOE sided with the challengers
- energystar.gov: consider replacing a heat pump or AC older than 10 years, a furnace older than 15
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