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Dual fuel or all electric: which heat pump setup fits your house?

Dual fuel (heat pump plus furnace) or All electric (heat pump plus electric back-up)

Compared by the people who run this site. Updated . Rebates and prices checked November 3, 2026.

Choosing dual fuel or all electric depends mostly on the age of the furnace you already own. A relatively new gas furnace makes dual fuel a low-regret step. With no gas service, or a furnace near its end, electric back-up removes a second fuel and its upkeep.

The verdict, by situation

  1. If your furnace is relatively new and it's the AC that needs replacing

    Dual fuel. ENERGY STAR says a heat pump can pair with the furnace "for a modest extra cost over an AC system." See also AC or heat pump when the AC dies.

  2. If your furnace is more than 15 years old and the whole system is up for review

    Price all electric first, then dual fuel with a new furnace. That age is ENERGY STAR's prompt to evaluate, and a furnace made on and after Dec. 18, 2028 must meet 95.0% AFUE.

  3. If you have no gas line at the house

    All electric, unless you already burn propane. The case for dual fuel rests on a furnace you already own. Propane owners can compare on propane or heat pump.

  4. If you live on the East side and want gas as a hedge against the coldest nights

    Dual fuel is a fair choice. Spokane normals show 2.2 days a year at 0F or below, so the furnace would carry those nights and the heat pump the rest of winter.

  5. If you live on the West side, with mild winters

    Dual fuel's cold-weather case is weak. Sea-Tac normals show 0.0 days at 0F or below. The reason to keep gas there is a sound furnace, covered on gas furnace or heat pump, west side.

A worn two-storey old house with a pickup parked in front, in Spokane's Hillyard district.
A worn two-storey old house with a pickup parked in front, in Spokane's Hillyard district.

Side by side

CompareDual fuelAll electric
Back-up heatYour gas furnaceElectric resistance strips
Fuel billsGas and electricElectric only
Yearly combustion checkYes, by a trained professionalNot needed
CO alarmNeeded for the furnaceNo furnace, but keep any alarms the house needs
Gas serviceStaysCan end, your decision
Control questionWhen the system switches fuelsWhen back-up strips engage
Heat at 5FFurnace can take overENERGY STAR Cold Climate floor: COP 1.75, 70% of 47F capacity
New-house code credits1.5 for a heat pump with a combustion supplement1.5 with a resistance supplement; 3.0 with none

Sources under the table: ENERGY STAR, DOH on yearly checks, ENERGY STAR criteria, WSEC-R Table R406.2. Code credits apply to new construction only. The table can't say which setup costs less on your rates, or at what outdoor temperature your system should switch.

What would change the answer

  • Your gas price. EIA's annual Washington figure rose from $12.72 in 2024 to $17.62 in 2025 per thousand cubic feet. Higher gas prices shrink dual fuel's advantage on cold nights.
  • Your electric price. Washington residential power was 14.63 cents per kWh in August 2026, up from 13.65 a year earlier.
  • A panel that can't carry electric back-up. State HEAR rebates cover required panel and wiring upgrades for households at or below 150% of Area Median Income, with no statewide amount.
  • A furnace that fails a yearly service visit. Dual fuel only makes sense on a furnace worth keeping, as repair or replace explains.
  • A final 2024 energy code. Proposed language adds electric readiness when an appliance uses gas or liquid fuel, but it's a proposal and the effective date of May 3, 2027 is not final.

What it costs, with dates

Nobody official publishes an installed price for either setup, and neither do we. Written bids should separate the heat pump, the back-up, the control or thermostat, electrical work and permits, so you can see what the second fuel adds or saves.

As of November 2026, the running-cost picture is mixed. Using EIA's 2024 Washington prices, our arithmetic gives about $14.56 per million Btu of heat from an 80% AFUE gas furnace and $14.47 from a heat pump at the Inland Empire's metered COP of 2.41. Run the 2025 gas price through the same math and the furnace row rises to about $20.2. Electricity moved too: at the state's August 2026 rate of 14.63 cents per kWh, a summer month used only for illustration, our arithmetic gives about $17.8 at COP 2.41 and about $14.1 at COP 3.05. Those are statewide averages, the COP comes from ductless pilot homes metered in 2008-09, AFUE is a rating, and duct losses aren't included. The complete comparison sits on what heat costs.

Rebates rarely favor one setup here, because most utility offers require electric heat today. Avista's page shows no heat pump amount (archived copy, June 2026), so confirm with the utility. No federal credit applies to a 2026 install, per the IRS FAQ.

Who does the work

Hire a registered HVAC contractor and confirm it on L&I's lookup. Refrigerant, gas lines, venting and line-voltage work all belong to licensed trades, and electrical permits come before the work. Have the contract say who pulls each one, as who pulls the permit lays out.

You can change the filter, clear around the outdoor unit and check a breaker or switch. If you smell gas, leave first. Touch no switches or plugs and don't use a phone inside. Once outside and away, call 911 and your gas utility: PSE 1-888-225-5773 (archived copy, September 2026; confirm with the utility), Cascade Natural Gas 888-522-1130 (archived copy, December 2025; confirm with the utility), Avista 800-227-9187 (archived copy, October 2025; confirm with the utility) or NW Natural 800-882-3377. If a CO alarm sounds, everyone goes out first, then call 911 from outside.

What actually decides when the furnace takes over?

The thermostat or control does, using a setting your contractor chooses with you. We found no official changeover temperature for Washington, so ask each bidder what setting they propose and why, using your rates. A proposal that can't explain its number is worth questioning.

ENERGY STAR advises a steady setpoint and avoiding Auto mode. Washington's code separately requires controls that keep supplementary heaters off above 40F. Ask how that rule applies to your equipment, whether the back-up is a furnace or electric strips.

A worn white digital thermostat reading 80 in cool mode on a beige wall.
A worn white digital thermostat reading 80 in cool mode on a beige wall.

Does the I-2066 ruling affect keeping gas?

Not in any way a homeowner can act on today. Washington's Supreme Court struck down Initiative 2066 in its entirety on Sept. 17, 2026, in the court's opinion (news-site copy). It is not law, and gas service itself did not end. No state agency statement on the practical effects was found, so don't buy a system based on a guess about what happens next. Regional context is on the east side starting page.

Parts and examples

A dual-fuel setup depends on the control that decides which fuel runs. To compare the control types a bid may name, see PlumbingSupplyAndMore's thermostat category. That store shares an owner with this site. Have your contractor choose and wire whatever goes on a dual-fuel system, since it has to match both pieces of equipment.

What people ask next

Can I add a heat pump to my gas furnace without replacing the furnace?

Often, when the furnace is relatively new. That's the setup ENERGY STAR describes as a modest extra cost over an AC system. A contractor has to confirm the match.

Does all electric mean relying on electric strips all winter?

No. The heat pump does most of the work and back-up fills in. ENERGY STAR says a ducted heat pump can deliver up to three times more heat energy than the electrical energy it consumes.

Do dual-fuel homes need a CO alarm?

Yes. CDC says gas furnaces make CO, and it advises detectors near every sleeping area along with yearly service.

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