Gas smell or carbon monoxide at a boiler
Get out first. SDG&E says to leave at once and call 911 or 1-800-611-7343, PG&E says to call 911 and then 1-800-743-5000, and SoCalGas asks you to evacuate and call 1-800-427-2200 from a safe place.
A soft yellow flame can indicate carbon monoxide, SDG&E says, and the appliance shouldn't be used again until a qualified, licensed professional confirms it's safe. SDG&E also wants a carbon monoxide detector on each floor of the home.
What boiler repair costs in California
We estimate $150 to $935 per repair for this job in California. That's a model, not a quote: one national published cost range, widened by 15 percent each side and adjusted by California's wage ratio to the US (1.16).
A boiler repair is estimated at $150 to $935 per repair, from a single national range widened 15 percent each side and adjusted by California's technician wage ratio of 1.16. That's an estimate, not a quote, so ask what the diagnosis costs apart from the part.
| Item | Figure | What it is |
|---|---|---|
| Estimated range, not a quote | $150 to $935 per repair | Built from one national published range, adjusted by the California HVAC technician wage ratio (1.16). California company prices are shown separately. Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Technician wage, California mean | $36.24 an hour | Technician pay from BLS (May 2025), which isn't a charge to you. |
| Mechanical gas appliance permit including hydronic heat, San Francisco | $290 | Table 1A-C category 1M, with hydronic heat named; applies to permits issued on and after July 12, 2026. |
How we estimate costs: the Estimated range row is a model, not a quote. We have no counted California company price for this job, so the range is our national estimate alone. Our national estimate takes one published national range for this job (a cost guide from a third-party site that we have not verified and do not cite) and multiplies it by California's HVAC technician wage ratio to the US (1.16, BLS OEWS May 2025, heating, air conditioning and refrigeration mechanics and installers). The wage and permit rows below are what HVAC technicians are paid and what a city charges, and neither is a price. We have not collected quotes. Full method. Prices as of Oct 23, 2026.
One more repair, or a new boiler
None of our California sources gives a boiler's service life, so age alone won't decide it. Get the diagnosis in writing, with the failed part, its price and the boiler's age, and get a second opinion if the estimate keeps growing.
- The company names the part and the price, and the rest of the system checks out.
- The diagnosis is a failure of the main vessel or heat exchanger, confirmed by a second company.
Which license covers a boiler
CSLB's C-20 class covers warm-air heating systems and water heating heat pumps with their ducts, flues and controls, and the classification text we cite doesn't mention boilers or hydronic piping. We can't name the class for boilers. Ask the company which classification on its license it uses for hydronic heating, then look the number up on CSLB's license check and read the status.
B&P 7048 lets someone work without a license only on a job under $1,000 that needs no building permit, and the exemption is lost if they advertise as a contractor or bring in help.
When a boiler job needs a permit
San Francisco's fee table names hydronic heat beside furnaces and heat pumps in its single-unit mechanical gas appliance category, at $290 for permits issued from July 12, 2026. Los Angeles requires a mechanical permit for any installation or modification of a heating system. CSLB's letter to C-20 contractors lists furnace, coil, air handler and condenser change-outs, and boilers aren't among them, so ask your building department how it treats a boiler replacement.
A yearly safety check
SDG&E recommends an annual safety checkup, and PG&E says to have a furnace serviced once a year. Ask what the visit includes, and name venting.
When a boiler fault can't wait for a booking
- You smell gas near the boiler: walk out, then call 911 and your gas utility.
- A carbon monoxide alarm sounds, or the burner flame has gone soft and yellow.
- People in the house have sudden headaches, nausea or drowsiness.
- The boiler heats, but the radiators warm unevenly and nothing smells.
Checks before you call
- Confirm the thermostat is calling for heat and its batteries are fresh.
- Look at the boiler's display or lights, and write down any code you see.
- If you've smelled gas, stop there: no panels opened, nothing relit.
Does a boiler repair need a permit?
San Diego says repair alone of a mechanical system needs no permit, and the sources we cite don't list small repairs as permit work. A replacement may differ. Your city or county building department decides how it handles a boiler, and CSLB sends you there because code requirements vary around the state.
Before any work starts, get the license number and check it with your state's licensing board; our state pages link the lookup.
Questions people ask
What does a boiler repair cost in California?
Our model puts it at $150 to $935 per repair; that's an estimate, not a quote. It rests on one national range adjusted for California pay, with no counted California company price for boiler repair behind it.
Which CSLB license covers a boiler?
We can't name the class; CSLB's C-20 text covers warm-air systems and doesn't mention boilers. Ask which classification on its license it uses for hydronic heating, then check the license on CSLB's lookup, which shows status and complaint disclosure.
Does a boiler replacement need a permit?
The sources we cite name furnace, coil, air handler and condenser change-outs; San Francisco's fee table names hydronic heat. San Francisco charges $290 for a single-unit mechanical gas appliance permit, a category covering furnace, hydronic heat and heat pump. Anywhere else, ask your building department.
What should I do if I smell gas near the boiler?
Leave the building and call 911 and your gas utility once you're outside. PG&E says never to use a flashlight, match or candle to look for a leak, and never to turn electric switches on or off while you suspect one.
Does a boiler need servicing every year?
SDG&E advises an annual safety checkup; none of the sources we cite makes it a legal requirement. Ask the company what its visit covers, venting included.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Heating, Air Conditioning, and Refrigeration Mechanics and Installers (SOC 49-9021), California, mean hourly wage Read Oct 23, 2026.
- SF DBI Table 1A-C (July 2026) Read Oct 20, 2026.
- Gas safety | San Diego Gas & Electric Read Oct 20, 2026.
- Carbon monoxide | San Diego Gas & Electric Read Oct 20, 2026.
- Gas Safety | PG&E Read Oct 20, 2026.
- Emergency Information | SoCalGas Read Oct 20, 2026.
- Carbon Monoxide | SoCalGas Read Oct 20, 2026.
- CSLB: Licensing Classifications Detail, C-20 Read Oct 20, 2026.
- CSLB: Check a License Read Oct 20, 2026.
- California Legislative Information: BPC 7048 Read Oct 20, 2026.
- LADBS: Mechanical HVAC Permits Read Oct 20, 2026.
- City of San Diego DSD: What Permits Do I Need? Read Oct 20, 2026.
- CSLB: C-20 Permit Enforcement Letter (PDF, 2010) Read Oct 20, 2026.
- CSLB: Do I need a building permit for my project? Read Oct 20, 2026.
- HVACMatch: how we estimate costs, California (editorial policy) Read Oct 23, 2026.