Heat Pump vs Gas Furnace in California: What Really Decides the 10-Year Cost?

By Andrew Salinas, owner of Modern Air · Updated September 17, 2026 · 8 min read

At California energy prices, gas usually heats cheaper per unit. Here is what actually decides the 10-year cost of a heat pump versus a gas furnace.

Over ten years in the South Bay, a heat pump and a gas furnace often end up closer in total cost than either side’s marketing suggests. At California’s current average energy prices, heating with an efficient gas furnace usually costs less per unit of heat than heating with a heat pump. The heat pump tends to catch up, and sometimes pull ahead, because one system replaces both the furnace and the air conditioner, local rebates cut the upfront cost, and the Bay Area’s 2029 furnace rule means a gas furnace bought now may be your last one.

We get asked this constantly, usually by someone holding two quotes and a lot of conflicting advice. The honest answer depends on a handful of things you can actually check for your own house, so here they are.

What goes into a 10-year heating and cooling cost?

Four things, and comparisons that skip any of them tend to mislead. There is the upfront cost of equipment and installation, the yearly energy to run it, maintenance and repairs over the decade, and any rebates that come off the top. A fifth factor hides inside the first one: a furnace only heats. If you also want air conditioning, the furnace path means buying and maintaining two systems.

The table below lines the two paths up on the factors that move the 10-year total. It is a starting point for your own comparison rather than a verdict.

Is a heat pump cheaper to run than a gas furnace in California?

Usually not for heating alone, at today’s average prices. That surprises people, because heat pumps are genuinely efficient. The catch is that California electricity is expensive and gas is comparatively cheap per unit of energy, so the efficiency advantage has a lot of ground to make up.

Here is the math on the cost to deliver one million BTU of heat into your home, using average California residential prices from the U.S. Energy Information Administration: $22.01 per thousand cubic feet of gas for 2025 and 34.74 cents per kWh of electricity for June 2026. Your actual rates will differ, and the rate plan you are on can shift the picture in either direction.

Two things soften that picture in the South Bay. Our winters are mild, so the house needs relatively little heat each year and the dollar difference is smaller than the percentages suggest. And against electric resistance heat, a heat pump wins by a wide margin, which is why homes with baseboard or electric furnaces nearly always come out ahead by switching.

Does replacing the air conditioner change the answer?

Yes, and for many South Bay homes it is the deciding factor. If your furnace and air conditioner are both near the end of their lives, the real comparison is one heat pump against a new furnace plus a new AC. That narrows the upfront gap considerably and leaves you with one system to maintain instead of two.

If your air conditioner is fairly new and only the furnace is failing, the furnace path looks stronger in the short term. A dual-fuel setup, with a heat pump doing most of the work and a gas furnace as backup on the coldest nights, is another option worth asking about in that situation.

How do rebates and the 2029 rule affect the math?

Rebates come straight off the heat pump side. Silicon Valley Clean Energy currently offers $2,000 when a heat pump replaces a gas furnace, or $3,000 for income-qualified households, across Morgan Hill, Gilroy, and much of Santa Clara County. San José Clean Energy offers its own EcoHome Rebate to San Jose customers. The federal 25C tax credit is gone for anything installed after December 31, 2025, so do not budget around it.

The 2029 rule matters for the second half of the decade. The Bay Area Air Quality Management District requires furnaces manufactured from January 1, 2029 to be zero-NOx, which in practice means electric. A gas furnace bought today can keep running, but its replacement will very likely be a heat pump anyway. See our California heat pump rebates guide for current programs.

Do heat pumps cost more to maintain?

Roughly the same, with a small edge to the heat pump for being a single system. A heat pump runs in both seasons, so it builds up more hours and should be serviced twice a year. The furnace-plus-AC path needs a furnace visit in fall and an AC visit in spring, which works out to about the same attention. Either way, a maintenance plan keeps both on the calendar and repair surprises down.

So which one is cheaper over 10 years?

It depends on your house more than on the technology, and anyone who gives you a flat answer without looking at it is guessing. As a rough guide from what we see in the South Bay:

• The heat pump usually wins when the AC also needs replacing, when you currently heat with electric resistance, when you qualify for a local rebate, or when you plan to stay past 2029.
• The gas furnace usually wins when your AC is newer, you rarely use cooling, and you mainly want the lowest heating bill at today’s prices.
• It is a close call in a lot of homes in between, which is exactly when a load calculation and a look at your rate plan are worth doing before you sign anything.

Whichever way you go, sizing decides more of the outcome than most people realize. An oversized or undersized system underperforms no matter what fuel it uses, and it is the most common reason a heat pump disappoints.

Quick quiz: which path fits your home?

Five questions, about a minute. Your verdict points to the path worth pricing first.

1. How old is your air conditioner?

• A. Failing or older than 12 years
• B. About 8 to 12 years
• C. Newer than 8 years, or we have no AC and do not want one

2. How do you heat today?

• A. Electric baseboard or electric furnace
• B. An older gas furnace
• C. A newer, efficient gas furnace

3. Which utility serves you?

• A. SVCE or San José Clean Energy
• B. Not sure
• C. Outside Santa Clara County

4. How long will you stay in the home?

• A. Well past 2029
• B. A few more years
• C. Selling soon

5. How much do you use cooling?

• A. Most summer afternoons
• B. During heat waves
• C. Hardly ever

Mostly A: A heat pump is very likely your better 10-year bet. Get a sized quote and apply for your rebate before installation.
Mostly B: Close call. Price both paths properly, including a load calculation, and ask about dual-fuel as a middle option.
Mostly C: A furnace replacement may make more sense for now. Keep the 2029 rule in mind for whoever owns the house next.

Get the numbers for your own house

Since 2009, Modern Air has helped South Bay homeowners make this exact decision without the hype, with more than 7,000 completed jobs behind us. We run a load calculation, look at your ducts and electrical panel, factor in your actual rate plan, and show you what one system versus two looks like for your home, including which rebates you can really claim.

We are a family-run company in Morgan Hill, CA License #935704. Call (408) 497-0444 for an honest comparison. Estimates are always free, and financing is available.

Frequently asked questions