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Heat Pump vs Gas Furnace in Washington: Costs, Code Rules, and Which One Fits Your Side of the Cascades

Choosing a heat pump vs gas furnace in Washington comes down to climate, rates, and rebates, and the rules changed after a 2026 court ruling and 25C's end.

Heat Pump vs Gas Furnace in Washington: Costs, Code Rules, and Which One Fits Your Side of the Cascades

West of the Cascades, a heat pump is the easier choice for most homes. East of them, the answer gets closer, and a gas furnace or a hybrid setup often earns a longer look. That is the short version, and your own utility rates, ductwork, and existing fuel can change it.

The legal and financial picture has shifted this year too. The Washington Supreme Court struck down Initiative 2066 in September 2026, the federal 25C tax credit is gone for equipment installed after 2025, and rebates now depend mostly on your local utility and your income.

Neither system wins everywhere. This guide walks through what each one costs, how each performs in the climates around the state, and what the current rules mean if you are replacing a system in an existing home. Prices here are approximate ranges based on typical quotes, and they will vary by contractor and house.

Upfront Price: What You Will Likely Pay

A new gas furnace is usually the cheaper purchase by itself. Installed prices for a typical home often run around $4,500 to $9,000, assuming a gas line and venting already exist. Adding a new central air conditioner can push the combined job to about $9,000 to $16,000.

A ducted heat pump commonly costs around $10,000 to $20,000 installed, and it replaces both the furnace and the air conditioner. Ductless mini-split systems can run from about $4,000 for a single zone to $15,000 or more for several zones. Those are useful for homes that heat with baseboards and have no ducts at all.

Electrical work can change the math. An older panel may need an upgrade before a heat pump goes in, which often adds a few thousand dollars. If you have no gas service today, adding a line for a furnace brings its own cost and may not make sense at all.

How Each One Handles Washington's Climates

Seattle, WA, Tacoma, WA, and Olympia, WA spend most of the winter in temperatures where a heat pump works well. A modern unit can deliver a lot more heat than the electricity it draws in those conditions. The June 2021 heat dome also reminded western Washington that many older homes had no cooling, and a heat pump solves both problems with one machine.

Spokane, WA and much of the Columbia Basin are a tougher test. Winter cold snaps can take temperatures near or below zero, and a standard heat pump loses capacity as the air gets colder. A cold-climate model sized correctly can still handle that load, but you should ask how much backup heat the system will use on those nights.

Gas furnaces do not care about outdoor temperature in the same way, and their hot, steady air is what many people are used to. They do nothing for summer, though, and hot Yakima, WA or Tri-Cities summers mean you will likely still need a separate cooling system.

Mountain, Coastal, and Island Homes

Elevation and access matter once you move away from the main population centers. Homes around Leavenworth, WA or the foothills may see deeper cold, along with snow that can pile against an outdoor unit, so stands and clearances deserve extra attention. Gas service may not reach those homes at all, which leaves a choice among propane, electric, and heat pump options.

Coastal areas such as Westport, WA or the San Juan Islands have mild temperatures that favor heat pumps, but salt air can age outdoor equipment. Ask about corrosion-resistant coil coatings if you live near the water.

Running Costs: Do the Math With Your Own Bill

Monthly savings depend on your local rate more than any statewide figure, because power prices differ widely between Seattle City Light, public utility districts, and investor-owned utilities. Published statewide averages for residential electricity have recently run around 14 to 15 cents per kilowatt-hour, and your own rate may sit well above or below that. Gas rates vary by utility and season as well.

Here is a simple method using your bills. One therm of gas holds about 29.3 kilowatt-hours of heat, so a 95% efficient furnace pays about your gas rate divided by 0.95 per therm of delivered heat. A heat pump averaging about 3 units of heat per unit of electricity costs your electric rate times 29.3, divided by 3.

As an illustration only, take 13 cents per kilowatt-hour and $1.60 per therm. The heat pump comes to about $1.27 per therm of heat, and the furnace comes to about $1.68. Run the same math at a much colder seasonal efficiency, or with your own rates, and the gap can narrow or flip.

Homes now using electric baseboards or an old electric furnace have the clearest case. Moving to a heat pump can cut heating electricity substantially, and rebates often favor exactly that conversion.

What the Code and the Courts Mean for You

Washington's current residential energy code took effect on March 15, 2024, and its heating credit rules matter most for new homes. It does not flatly require heat pumps. Instead, it uses a credit system that rewards heat pumps with points and gives gas systems none, so builders using gas need to make up the difference with other efficiency measures.

A newer 2024 edition is moving through the rulemaking process. A state filing from this year proposed a May 3, 2027 effective date, so check with the State Building Code Council or your local permit office if you are planning a new build. Rules can change between a proposal and a final version.

Initiative 2066, approved by voters in 2024, aimed to protect natural gas access and unwind parts of the energy code. On September 17, 2026, the Washington Supreme Court ruled 6-3 that the measure was unconstitutional in its entirety. That ruling does not ban gas furnaces, and if you own a home with a working furnace, it does not by itself require you to remove it.

Rebates and Tax Credits Today

The federal 25C credit, which once covered up to $2,000 of a qualifying heat pump, ended for property placed in service after December 31, 2025. Any contractor still promising that credit on a current installation is working from old information. Ask for the rebate figures in writing and confirm them yourself.

Utility rebates are the main source of help, and they differ by utility and by the type of switch you are making. Puget Sound Energy lists rebates for electric resistance to heat pump conversions, hybrid heat pumps, and heat pump upgrades, all for existing single-family homes. Its rebate for going from gas to a heat pump is limited to income-qualified customers, so a gas customer above that limit should not count on it.

Published rebate amounts for other utilities change often, and the third-party figures we checked conflicted, so call your utility directly before you budget around any number. Seattle City Light, Avista, and the public utility districts each run their own offers. Seattle also has a separate program for oil-heated homes that convert to heat pumps.

The state also funds the Home Electrification and Appliance Rebates program through local administrators. It covers heat pumps for households at or below 150% of area median income, including renters, and each administrator sets its own details. Commerce lists 40 organizations, so check which one serves your county and whether funds remain.

Which One Should You Choose

Most homes west of the Cascades with existing electric heat or an aging furnace should start by pricing a heat pump. You get heating and cooling from one system, and the rebate outlook is usually better if you are moving off electric resistance.

A gas furnace still makes sense in some cases. It may be the practical answer if your furnace just failed, your ducts and gas line are in good shape, your cooling needs are small, and your budget will not stretch to a larger job. In colder parts of eastern Washington, a hybrid system that pairs a heat pump with gas backup can reduce the risk of expensive backup heat on the coldest nights.

Before deciding, ask each contractor for a load calculation and a written comparison of both options. You can start with Washington heating and cooling contractors in our directory, and it helps to get bids from companies that install both types. Our home energy and maintenance articles on the blog can help with the rest of your planning.

Heat Pump and Furnace Questions

Is a gas furnace still legal to install in Washington?

Yes, nothing in the 2026 court ruling or the current code's credit system bans a gas furnace in an existing home. Permit rules still apply to the replacement, and new construction faces the code's credit requirements. Your local building department can confirm what your project needs.

Will a heat pump keep up in Spokane, WA?

A properly sized cold-climate model can, though it may use backup heat on the coldest nights. Ask the contractor for the system's rated capacity at around 5°F and how much backup it will need. A hybrid setup with gas is another option if you already have gas service.

Can I get a rebate if I am switching from gas to a heat pump?

Possibly, but it depends on your utility and income. At Puget Sound Energy, the gas-to-electric rebate is reserved for income-qualified customers, and the state rebate program uses a 150% of area median income limit. Call your utility and your local administrator before signing a contract.