Boiler Replacement Cost in Marin & Sonoma (2026)
In 2026, a high-efficiency boiler replacement in Marin or Sonoma County runs $8,500–$15,000 installed. A combi boiler that also heats your water runs $11,000–$16,500, and a boiler with an indirect water heater $19,000–$29,000. Venting, near-boiler piping, controls and access decide where your home lands, and you get a free written estimate before we start.
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2026 boiler replacement cost by scenario
These are installed, permitted prices for our service area. Each one covers the boiler, labor, the standard piping and venting that go with it, and startup.
Also a custom quote: air-to-water heat pumps for radiant floors (see below). Repairs: call for a quote. 2026 pricing. Every home is different; these are ranges, not a price list, and permit fees are included in the price we quote.
Why can a combi come in under a boiler with a separate tank? It is one appliance with one vent and one set of gas, water and electrical connections. The trade-off is hot water capacity. A house with three or four bathrooms and morning showers that overlap is usually better served by an indirect tank, and that extra equipment and piping is what puts that option in the highest range.
What drives the cost of a new boiler
Two houses on the same street with similar boilers can end up at opposite ends of a range. These are the reasons, roughly in the order they move the number for us.
The vent route
A condensing boiler vents through PVC, CPVC, polypropylene or stainless pipe, depending on what the manufacturer specifies. A short, straight run out a side wall is quick. A long run, a roof penetration, or a path through finished rooms adds labor and material.
Piping at the boiler
Most quotes hide this line. A modern boiler wants primary/secondary piping or a low-loss header that keeps its flow separate from the zones. An old boiler piped straight through means we re-pipe that section, which often decides low end versus high end.
Zones, pumps & outdoor reset
Every zone needs a circulator or zone valve and a thermostat. Moving to ECM circulators and outdoor reset, which runs the boiler only as hot as the weather calls for, is the +$1,200–$4,500 line, and it lets the new boiler work as designed.
Combi or indirect tank
Deciding whether the boiler also makes your domestic hot water changes the price more than any other single choice. Compare the combi and indirect ranges above.
Manifolds and floor loops
In a radiant home, tired manifolds, actuators and mixing valves are often rebuilt along with the boiler. A leaking loop in the slab is its own diagnosis, and we tell you about it before we price a boiler around it.
Where the boiler lives
A basement with a door to the driveway is one job; a crawlspace below a long flight of hillside steps is another. On stair-only lots in Mill Valley, Sausalito and Tiburon, everything is carried in by hand. Wall-hung boilers are smaller and lighter, which helps.
Gas line size
A high-efficiency boiler needs the right pipe size and pressure at full fire. We check gas sizing on every install, and now and then an undersized line has to be upsized.
Town requirements
Every replacement is permitted, and inspectors ask for different things. Tiburon’s boiler handout wants a floor drain in the boiler room, a supported expansion tank, and smoke and CO alarms at inspection. Permit fees are included in the price we quote.
Size before brand
The name on the front matters less than people think; getting the size right matters more. Copying the old nameplate often oversizes the new boiler, and an oversized boiler short-cycles and wears out sooner. We size from the house.
- Outdoor reset and zone controls are set up at startup, so the boiler modulates with the weather instead of running at one fixed temperature.
- Old pumps are a common add-on. Swapping them for ECM circulators at the same visit saves a second trip later.
- Venting to the manufacturer’s specs is part of every price above, not an extra.
Want your number instead of a range? Get a free estimate.
What a real job cost: a Mill Valley boiler replacement
Aging cast-iron boiler out, NTI TRX in
This Mill Valley home was still heating its radiant system with an aging cast-iron boiler. We removed it and installed a new NTI TRX high-efficiency boiler, a new ECM circulator pump and upgrades to the radiant manifold.
What every price above includes
- Removing and disposing of the old boiler
- A new high-efficiency boiler sized for your home, not for the old nameplate
- Primary/secondary piping, closely spaced tees or a low-loss header
- A gas sizing check and pressure test
- Venting to the manufacturer’s specs, and condensate routed to an approved drain
- Startup with combustion analysis, outdoor reset and zone setup
- The permit, with fees included, and a walkthrough of your new system
More detail by town: Mill Valley boiler replacement · Tiburon & Belvedere · Sausalito · San Rafael · Healdsburg.
Does the brand change the price?
Not by much. The brands we install mostly land inside the same ranges, and the system around the boiler moves your number more than the logo does.
NTI: TRX, TFT, TRX Combi
Our go-to for radiant homes and multi-zone systems, heat-only or combi. Quiet, with strong modulation and a stainless heat exchanger. Most NTI installs carry our 3-year labor warranty.
Navien: NFC, NCB-E, NHB, NFB
Wall-hung and small, so it suits tight mechanical rooms. A frequent pick when one combi replaces both a boiler and a water heater.
HTP, Lochinvar, IBC, Laars, Viessmann
HTP’s UFT Combi is rated up to 95% AFUE. Lochinvar Knight fits larger systems, Laars fits compact closets, and IBC suits radiant and multi-zone work. We pick what fits the house.
Munchkin
No longer made, and parts are limited. We still repair them when the numbers make sense, and plan a replacement when they don’t.
Triangle Tube
The company shut down in November 2025, with no warranty on purchases after November 3, 2025 and parts only while stock lasts. Some Prestige models were also in a 2025 CPSC recall.
Two-boiler cascades
Some large homes run two boilers together so one can carry mild days and both can run in a cold snap. Those systems are a custom quote, priced after a site visit with a free written estimate.
A cascade or a large multi-zone radiant system is where a published range stops being useful, because the piping, controls and number of zones vary so much from house to house. We walk the system, then put a written price in front of you. See our boilers & radiant heating page for the full range of hydronic work we do.
Repair it or replace it: how to decide
A boiler with good years left should be fixed, not sold off. Here is the test we use.
Repair usually wins when…
- It is younger than roughly 12–15 years, with no leaks or cracks in the heat exchanger
- The fault traces to one worn component, say an igniter or flame sensor, a pump or zone valve, or a fill valve or expansion tank
- Parts for your model are still easy to get
Replacement usually wins when…
- It has 15–25 winters behind it, or corrosion or cracks have reached the heat exchanger
- You are paying for a repair visit every winter
- An old cast-iron or atmospheric boiler is feeding low-temperature radiant floors, a poor match that wastes gas
- It is a Triangle Tube or an older Munchkin and parts are getting scarce. Planning now keeps a January breakdown from becoming a long wait for parts with no heat.
Homeowners who move to a high-efficiency boiler often cut gas use by 15–30%. That adds up over the life of the boiler, but on its own it rarely justifies pulling out one that still runs well, and we will say so if yours has life left. Repairs are priced after we diagnose, so call for a quote. More on our boiler repair and radiant heating repair pages.
Gas boiler rules and heat pumps for radiant
BAAQMD Rule 9-6 (October 2026)
- You can still buy and install a gas boiler. Under the current rule, home gas boilers made after January 1, 2031 must be zero-NOx.
- A proposed amendment would move that date to 2033. The Air District Board votes on November 4, 2026.
- The rule only applies when a boiler is sold or installed. A working boiler can stay, and it can still be repaired.
- Healdsburg and northern Sonoma County are under the Northern Sonoma County Air Pollution Control District, not BAAQMD. We check your address before we quote.
- The smaller gas water heater date is a separate story: see our 2027 gas water heater rule guide.
Air-to-water heat pumps: custom quote
If you expect a new boiler to last 15 to 20 years, it is worth asking whether an air-to-water heat pump could run your radiant floors instead. Whether it fits depends on your floors, how warm the water needs to be, the house and your electrical panel, so we price these as a custom quote after a site visit.
Sonoma Clean Power lists up to $3,500 for an air-to-water heat pump that also makes domestic hot water, or $1,000 for one that only heats and cools. Those amounts are as of fall 2026; check current terms at sonomacleanpower.org before you count on them.
Rebates and permits for a new boiler
Gas boiler rebates: none we know of
We are not aware of any current rebate for a new gas boiler in Marin or Sonoma. The programs people ask about have ended or filled up:
- Federal 25C tax credit: covered equipment placed in service by December 31, 2025
- TECH Clean California: single-family heat pump incentives fully reserved since November 14, 2025
- HEEHRA: single-family rebates fully reserved statewide since February 24, 2026, with a waitlist
Be wary of any quote that subtracts a rebate nobody has verified. If a new program opens, we will update this page.
Permits: we pull them, fees included
- City of Mill Valley issues its own plumbing and mechanical permits. Tam Valley, Homestead, Strawberry, Almonte and Alto have Mill Valley addresses but are unincorporated, so Marin County permits them.
- Unincorporated Marin offers online mechanical permits, and replacement jobs don’t need plans.
- Tiburon requires a permit for a boiler replacement, and Belvedere requires permits for all plumbing and mechanical work.
- Unincorporated Sonoma (Permit Sonoma) issues heating equipment replacement, including piping, gas and vents, without plan check.
- San Rafael, Novato, Petaluma, Santa Rosa and other cities run their own building departments. If your boiler has a potable-water connection, Marin Water also requires backflow protection.
Permit fees are included in the price we quote.
Boiler replacement cost FAQ
How much does a new boiler cost in Marin or Sonoma County in 2026?
A high-efficiency boiler replacement costs $8,500–$15,000 installed in 2026. A combi boiler runs $11,000–$16,500, a radiant heating boiler system $12,000–$18,000, and a boiler with an indirect water heater $19,000–$29,000. Venting, piping, controls and access decide where a given home falls.
Is a combi boiler cheaper than a boiler and an indirect water heater?
Usually, yes: a combi runs $11,000–$16,500, while a boiler plus an indirect tank runs $19,000–$29,000. A combi suits homes with moderate hot water use. Larger households that run several showers at once are often better off with the indirect tank.
How much does it cost to replace a radiant floor boiler?
A radiant heating boiler system costs $12,000–$18,000 in 2026, including mixing, manifolds and low-temperature controls. Pump, manifold and valve upgrades add $1,200–$4,500. Adding or re-piping radiant zones is a custom quote after a site visit.
Why does boiler replacement cost so much in the Bay Area?
Most of the price is skilled labor, not the boiler. The near-boiler piping, venting, controls, gas sizing, permit and startup all take time, and hillside access or an older house adds more.
Are permit fees included in your boiler price?
Yes. Permit fees are included in the price we quote, and we pull the permit and schedule the inspection with whichever city or county governs your address.
How long does a boiler replacement take?
Most boiler replacements take 1–2 days on site. Hard-to-reach mechanical rooms or larger radiant re-piping can take longer, and we tell you that in the estimate.
Are there rebates for a new gas boiler in 2026?
We don’t know of any current rebate for a new gas boiler in Marin or Sonoma. The federal 25C credit ended with 2025, and TECH and HEEHRA single-family heat pump funds are fully reserved. Sonoma Clean Power lists rebates for air-to-water heat pumps (as of fall 2026; check current terms).
Can I still install a gas boiler in the Bay Area?
Yes. Under BAAQMD Rule 9-6, home gas boilers made after January 1, 2031 must be zero-NOx, and a proposed amendment would move that to 2033, with a Board vote on November 4, 2026. The rule applies only at sale or installation, so a working boiler can stay.
We replace boilers across Marin and Sonoma counties from our San Rafael base. Start with our boiler replacement service page, or see boiler repairs, radiant heating repairs and all of our boiler and radiant services. Questions first? Contact us.
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