Central Heating Not Working in California: Why You Have No Heat and What the Fix Costs
When the heating won't come on, the cause is usually one of a handful of things — and knowing which one tells you whether it's a five-minute fix or a service call. California homes that run on boilers and hot-water (hydronic) heating have a specific set of failure points, and cold homes aren't just uncomfortable: the landmark Marmot Review on the health impacts of cold housing found clear links between inadequately heated homes and respiratory and cardiovascular harm, especially for older residents and young children (review on Google Scholar). That's reason enough not to "wait and see" for long. Here's how to narrow it down.
Start with the thermostat
Before assuming the worst, rule out the cheapest cause. Confirm the thermostat is set to heat and above room temperature, replace its batteries if it's battery-powered, and check that a smart or programmable thermostat hasn't reverted to a schedule or lost its settings. A surprising share of "boiler is dead" calls are a blank or misconfigured thermostat — free to fix yourself, or a modest service call if the thermostat itself has failed.
Check the boiler's pressure and status
Most boilers have a pressure gauge that should read within a marked band (commonly around 1-1.5 bar when cold). If it's reading low, the boiler may lock out and refuse to fire — sometimes fixable by topping up via the filling loop, but a pressure that keeps dropping means a leak somewhere, which is its own boiler-leak problem. Also look for a fault or lockout code on the display; note it before resetting, because it tells the technician exactly where to look.
Ignition, pilot, and gas supply
If the boiler tries to fire but won't stay lit, the problem is usually in the ignition or pilot system — a failed thermocouple, a dirty flame sensor, or a faulty igniter — the same family of faults we cover for water heaters in our guide to a pilot light that won't stay lit. Confirm other gas appliances (stove, water heater) still work; if nothing gas-powered runs, the issue may be the gas supply itself, and you should treat any smell of gas as an emergency — see gas leak safety.
Circulator pump and zone valves
If the boiler fires and gets hot but no heat reaches the radiators or floor loops, the circulator pump that moves hot water through the system may have failed or seized, or a zone valve may be stuck closed. This is common in older systems and is a plumber/HVAC repair, not a DIY one. Expect the diagnostic call plus a $300-$700+ range for a replacement circulator pump depending on the unit, and less for a zone valve.
What the common fixes cost
- Thermostat replacement: roughly $150-$400 installed, more for high-end smart models.
- Thermocouple / ignition parts: commonly $150-$350.
- Circulator pump: often $400-$800 installed.
- Zone valve or valve actuator: typically $250-$500.
- Diagnostic / call-out only: see our emergency and call-out fee guide if it's after hours.
For a fuller parts-and-labor breakdown, our boiler repair cost guide and hydronic heating repair guide go deeper. If the system is old and failing repeatedly, weigh the cost of replacing the boiler instead.
When to stop troubleshooting and call
Reset the boiler once; if it locks out again, stop and call a pro rather than repeatedly resetting, which can mask a genuine safety fault. Any gas smell, soot, or a carbon-monoxide alarm means leave it off and get a technician out. Describe the symptom and any fault code on Plumber Comparator and request a free quote from a licensed local heating pro in Oakland, Fresno, or Riverside.
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