When the heat stops in a home in Novato, San Rafael, San Anselmo, Larkspur or Sausalito, the cause is most often simple: a thermostat that is not calling for heat, a filter so clogged that a safety switch shuts the system down, a pilot or igniter that fails, or a blower that will not start. Less often it is a gas valve, a control board or a cracked heat exchanger. The type of system narrows the list quickly, so that is where a heating repair begins.
Which heating system do you have?
Forced-air gas furnace. A furnace in a closet, garage, attic or crawlspace that blows warm air through ducts. Most no-heat calls in Marin involve one of these. Our furnace repair page walks through its ignition and safety sequence in detail.
Heat pump. An outdoor unit that looks like an air conditioner but also heats. Its faults - defrost problems, a stuck reversing valve, low refrigerant - are covered on heat pump services.
Wall furnace. A slim gas heater set into a wall, common in smaller older houses and apartments. Many have a standing pilot, a thermocouple or thermopile that proves the flame, and a gas valve that runs on the tiny voltage the pilot makes. When the pilot will not stay lit, the cause is usually a dirty pilot, a worn thermocouple or a draft at the vent.
Gravity furnace. A large furnace in the basement or crawlspace of an early-1900s home, with wide ducts and no blower: warm air simply rises. These are very old by now. Their ducts and insulation can contain asbestos, so we inspect without disturbing anything and tell you what we see.
Hot-water boiler. Heat through radiators or baseboard. Common faults are a failed circulator pump, low system pressure, air trapped in the lines and a worn expansion tank.
Safety comes before the repair
Every heating call starts with a safety inspection, because heat in most Marin homes still means burning gas. We check for gas leaks at the fittings, look at the flame, confirm the flue draws properly and test for carbon monoxide around the appliance. Only then do we move to diagnostic testing, find the failed part, explain your options and make the repair. Before leaving we run the system through a full heating cycle and check again that it operates safely.
If a carbon monoxide alarm sounds or you smell gas, do not wait for a visit: get everyone outside and call 911. Our emergency HVAC page lists what to do first in each situation.
What the symptom tells us
| What you notice | Common cause |
|---|---|
| System runs but the air is cool | Ignition failure, pilot out, gas supply or a heat pump stuck in the wrong mode |
| Some rooms warm, others cold | Leaky or crushed ducts, closed dampers, an undersized return |
| Strange odors when it runs | Dust, a cracked heat exchanger, an overheating motor or a gas leak |
| Turns on and off every few minutes | Dirty flame sensor, overheating from a clogged filter, oversizing |
| Pilot light will not stay lit | Dirty pilot assembly, worn thermocouple, drafts |
| Thermostat not responding | Dead batteries, wiring fault, failed transformer |
| Heating bills higher than last winter | Dirty filter or burners, duct leaks, a failing part running longer |
| Banging, squealing or rumbling | Delayed ignition, worn blower bearings, loose panels |
For more on the patterns behind these, see furnace not heating, uneven temperatures and thermostat not working.
Heating season in Marin
Marin winters are cool and damp rather than freezing, so heating runs for much of the year - from fall into late spring, and on foggy summer mornings near the water in Sausalito and Larkspur. Systems here wear out from long hours, not extreme cold. Equipment in damp crawlspaces also rusts: burners, igniters and gas controls corrode faster under a house than in a dry closet. A fall maintenance visit catches most of that before the first cold week.
Second opinions and honest pricing
If another company has told you the heat exchanger is cracked or the whole system needs replacing, ask us to look. We show you what we find, recommend only the repairs you need, and give you an itemized price before any work begins. Repairs use factory certified parts with the manufacturer’s warranty, and our work carries a labor warranty. Town pages: heating repair in San Rafael and in San Anselmo.