Boiler vs. Furnace vs. Heat Pump: Which Heats a California Home?
If you searched for boiler prices, the real question is probably one step earlier: should your California home be heated by a boiler at all? Most of the state's housing stock is not plumbed for hydronic heat, and quoting a boiler for a house with no radiators is a far larger project than a like-for-like swap. Here are the three realistic options.
How each one makes heat
- Boiler (hydronic): burns gas to heat water, then circulates it through radiators, baseboard convectors or floor tubing. Needs a water loop, a circulator pump, an expansion tank and zone valves.
- Furnace (forced air): burns gas to heat air, which a blower pushes through ductwork to registers. Efficiency is rated in AFUE — typically 80% standard, 90-98% condensing.
- Heat pump: burns nothing. It runs a refrigeration cycle in reverse to move heat from outdoor air indoors, which is why it delivers more heat than the electricity it draws. The same box cools in summer, ducted or ductless.
Why boilers are rare in California
Nationally, roughly two-thirds of homes are heated by a furnace and only a small single-digit share by a boiler; California skews further still. The reason is air conditioning: once central cooling became standard, homes needed ductwork anyway, and once ducts exist, adding a furnace is the cheapest way to heat. A boiler cannot use ducts at all.
Where boilers do show up, it is older San Francisco and East Bay housing, historic Sacramento neighborhoods, multi-family buildings, mountain homes, or high-end builds that chose radiant floor heating. If you already have radiators or radiant tubing, a boiler is very likely still the right move — see our boiler replacement cost guide and the combi boiler option. If you have ducts, retrofitting hydronic distribution from scratch costs more than the appliance itself and rarely pays back.
Installed cost, side by side
Each range below is cross-checked against several 2026 national cost datasets and adjusted for California's high labor rates and low heating loads. A sanity check, not a quote.
- Gas boiler, like-for-like replacement: roughly $4,000-$12,000. Standard cast-iron units sit at the bottom; condensing and combi units, awkward access and repiping push to the top.
- Gas furnace, like-for-like replacement: roughly $4,000-$10,000. California's mild climate allows smaller BTU sizing; a 96% AFUE condensing unit needing new venting and a condensate drain costs well more than an 80% unit.
- Ducted heat pump (heat and cool in one): roughly $8,000-$20,000 installed. The spread reflects panel work, duct sealing or resizing, and whether a new air handler is needed.
- Ductless mini-split heat pump: roughly $2,000-$7,000 per zone — the answer when there are no ducts at all.
- Adding hydronic distribution where none exists: the boiler is the small line item. Radiators, tubing, manifolds and floor buildup dwarf it — the main reason a boiler quote lands far above any "average boiler cost" figure.
One comparison people get wrong: a heat pump replaces a furnace and an air conditioner. Compare it against furnace-plus-AC and the gap narrows.
What they cost to run in California
Here California differs from the rest of the country. Residential electricity is among the most expensive in the nation — major utility rates in 2026 sit in the high-30s to low-40s cents per kilowatt-hour on standard tiered plans — while delivered gas runs a couple of dollars per therm. Do the arithmetic on delivered heat and a gas furnace often still edges out a heat pump at real-world seasonal efficiency, unless:
- You have rooftop solar, which drops the heat pump's marginal running cost toward zero on sunny days.
- You are on a time-of-use plan and heat mostly off-peak.
- You are replacing electric resistance heat or an old wall furnace, where a heat pump wins anyway.
The economics are not hypothetical. A 2021 study by Deetjen, Walsh and Vaishnav in Environmental Research Letters simulated roughly 22,000 representative homes across 55 US cities and found that about a third of single-family homes would come out ahead financially on a heat pump once the extra install cost over a gas furnace was counted, while cutting emissions (study on Google Scholar). A third is meaningful — and a reminder that it is not everyone.
Upkeep matters too: a short-cycling furnace or radiators that never get hot waste money quietly, as does central heat that keeps cutting out.
Does hydronic really feel better?
Boiler owners swear by the comfort: no drafts, no blower noise, no dust. But the research is more measured than the marketing. A 2017 critical literature review by Karmann, Schiavon and Bauman of UC Berkeley's Center for the Built Environment, in Building and Environment, compared thermal comfort in radiant versus all-air buildings and found that among the conclusive studies, most showed no clear preference, a minority favoring radiant (study on Google Scholar). For a homeowner: hydronic is at least as comfortable as forced air, sometimes better — but not by enough to justify tearing up floors in a ducted house.
Plumber or HVAC contractor?
California's Contractors State License Board splits this cleanly:
- C-4 (Boiler, Hot Water Heating and Steam Fitting): boilers, steam fitting, piping, valves, pumps, radiators and convectors.
- C-36 (Plumbing): the gas piping feeding a boiler or furnace, plus much of the wet side of a hydronic system. Many radiant jobs go to plumbers holding C-36 alongside C-4 — see what a C-36 license covers.
- C-20 (Warm-Air Heating, Ventilating and Air-Conditioning): furnaces, ductwork, registers, blowers, air conditioning and heat pumps — the license to look for on a heat pump bid.
In practice a furnace or heat pump is an HVAC job with a plumber subcontracted for the gas line; a boiler or radiant job is a plumbing job with an electrician for controls. Verify the classification on the CSLB site before signing, and price gas work against our gas line cost hub.
A simple way to decide
- Radiators or radiant floors, failing boiler: replace the boiler; converting to forced air means new ducts throughout.
- Ducts, dying furnace, no AC: price a heat pump seriously — you get cooling in the same project, and the numbers most often work here.
- Ducts, dying furnace, AC you like: a replacement furnace is usually cheapest; price a heat pump too if you have solar.
- No ducts, old wall heaters: mini-splits usually beat both, zone by zone — see our gas wall heater guide.
- Electrifying anyway: pair it with water heating — our heat pump water heater guide and the water heater installation hub cover that side. State-backed heat pump incentives have periodically run out of funding, so confirm availability before budgeting a rebate.
Whatever you lean toward, insist on quotes that break out the appliance, the distribution work (ducts or piping), the gas or electrical work and permits separately — a lump sum makes these bids impossible to compare. Compare licensed contractors in Los Angeles, Sacramento, San Jose and Oakland on Plumber Comparator, and request a free quote describing what you have today: radiators, ducts, or neither.
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