Furnace Not Heating in Berkeley

Furnace Not Heating in Berkeley

Berkeley is a heating town more than a cooling town. The bay keeps summers cool, so when people call us it is far more often about a furnace that has stopped putting out heat than an AC that has quit. That changes what we look for. The housing here is old, mostly Craftsman bungalows in the flats and mid-century homes in the hills, and a lot of these homes still run aging gas furnaces or original wall and floor heaters.

On most of these calls the fix is one part: a cracked igniter, a carboned flame sensor, a limit switch tripped by a clogged filter, or a tired control board. What makes Berkeley different is the age of the equipment behind the symptom. Once a furnace is into its late teens we stop just clearing the no-heat complaint and start inspecting the heat exchanger for cracks, because an old unit with a CO risk is a safety call, not a comfort call.

We run combustion analysis and CO testing on every gas furnace we open in Berkeley. If the fix is a $200 igniter, that is what goes on the estimate. If we find a cracked heat exchanger on an old unit, we show it to you on camera and walk through repair versus a heat pump conversion.

Common causes

Cracked hot surface igniter. The standard no-heat failure on newer gas furnaces. The igniter cracks from repeated heating and stops glowing, so the burners never light. We confirm with a continuity test and replace it. Quick fix on most units.

Dirty or failed flame sensor. The furnace lights and then shuts off within seconds because the sensor can't prove the flame. The board closes the gas valve for safety. Cleaning the carbon off usually restores it. We replace only when the sensor itself is degraded.

Pilot and thermocouple on older units. Many Berkeley homes still run pre-2000s furnaces with a standing pilot. If the pilot won't stay lit, the thermocouple is usually the culprit, not relighting the pilot over and over. We test the thermocouple millivolt output and replace it if it has dropped off.

Limit switch tripped by a dirty filter. A neglected filter restricts airflow, the heat exchanger overheats, and the limit switch shuts the burners down to protect it. People read that as a dead furnace. We check the filter, clear the restriction, and confirm the switch resets and holds.

Cracked heat exchanger on aging equipment. On older furnaces, a no-heat complaint sometimes uncovers a cracked heat exchanger, which is a CO safety issue. We inspect with a camera and show you the crack. This usually means replacement, and in Berkeley a heat pump conversion is often the cleaner path.

Control board failure. An old board can lose the relay that fires the ignition sequence. We read the fault code and trace the sequence to confirm the board is actually the failure and not a wiring or sensor issue upstream of it.

How we diagnose it

• Confirm the thermostat is calling for heat and the furnace is getting power and gas.
• Watch the full ignition sequence and read any fault code off the board.
• Run combustion analysis and CO testing, mandatory on every gas furnace open.
• Inspect the heat exchanger with a camera on any older unit.
• Lay out the repair cost, or the repair-versus-heat-pump math, on a written estimate.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

Furnace Not Heating in Berkeley: common questions

Nearby and related

Furnace Not Heating near Berkeley: Oakland · Richmond .

This is usually a furnace repair in Berkeley job. See our furnace repair overview or the Berkeley service area.