Heating trouble in Sunnyvale, Santa Clara and Cupertino rarely means a dead system. Most calls between November and March come down to one stage of the heating sequence that stopped working: the thermostat is not calling, a clogged filter is choking airflow, an igniter or flame sensor has failed, or a safety switch has shut the burners down. A good visit finds which one with readings, then separates routine maintenance, a targeted repair and replacement timing instead of starting the conversation with a new system.
Which heating system do you have?
The next step depends on the equipment, and homes here use several kinds:
| Heat source | Where you usually find it | Typical service calls |
|---|---|---|
| Gas forced-air furnace | 1950s–1970s homes, in a hall closet, garage or attic | Ignition, flame sensor, pressure switch, blower, heat exchanger |
| Electric furnace or air handler with heat strips | Some condos and homes without a gas line | Heating elements, sequencers, breakers, blower |
| Heat pump, ducted or ductless | Newer installs and furnace-plus-AC replacements | Defrost, reversing valve, auxiliary heat, refrigerant |
| Boiler with radiant floor tubing | Eichler homes, tubing in the concrete slab | Circulator pump, leaks, controls, boiler ignition |
Furnace repair, replacement and maintenance
Gas furnaces are still the most common heat in the area. The furnace repair page walks through the start-up sequence a technician tests and the symptoms that point to each part, including pilot light and ignition problems on older units and blower motor repair when the burners light but little air reaches the rooms. A heat exchanger inspection belongs in every safety check, because a crack there can let combustion gases into the airstream.
When a furnace is past repair, furnace installation covers sizing, efficiency choices and venting changes. Furnace replacement and the yearly furnace tune-up have their own pages, as do gas furnace and electric furnace service.
Heat pumps
A heat pump heats and cools with one outdoor unit, which makes it a natural option when an old furnace and AC wear out together. Heat pump repair explains defrost, reversing-valve and auxiliary-heat faults; heat pump installation covers electrical capacity, outdoor unit placement and duct condition. In homes without ducts, ductless mini-splits do the same job room by room.
Boilers and radiant floor heat
Many Eichler homes in Sunnyvale and Cupertino heat through tubing in the slab, fed by a boiler. These systems are quiet and even, but a failed circulator pump, a leak or an aging boiler can leave the whole house cold, and the fix starts with finding which part of the loop stopped. See boiler repair, boiler installation and radiant floor heating.
When heating trouble is urgent
A gas smell, a carbon monoxide alarm, a burning electrical odor or a furnace that keeps shutting itself off should not wait for a convenient day. Get everyone outside first if you smell gas or the CO alarm sounds, and call from there. Phone lines are staffed 24/7, and urgent no-heat calls get the earliest opening. The emergency service page explains how calls are triaged, and emergency heating repair covers the heating side.
Before the visit: describe what changed
Note whether the system starts at all, runs but blows cool air, or shuts off after a few minutes, and whether the main symptom is airflow, temperature, a new noise, a smell or water. Write down the thermostat setting, any flashing light on the furnace and the equipment’s age if you know it. Those details shorten the diagnosis.
What the diagnostic covers
Ask which checks are included before you approve repair work. Ours covers the thermostat and control wiring, electrical readings on motors and igniters, airflow and the filter, safety switches, visible wear and access conditions in the closet, attic or crawlspace. You get the findings, repair options and cost factors before anything is replaced, and parts are matched to the brand, model and age of your equipment.
Gas or electric heat?
Neither wins in every house. A heat pump moves heat rather than burning fuel, and mild winters suit it; a gas furnace can still cost less to run depending on rates and insulation. The heat pump vs furnace guide lays out the trade-offs.
Local notes
We have worked on heating systems here since 2009. Winters are mild, but nights from November to March are cold enough to keep furnaces and heat pumps busy, and a furnace that sat idle since spring often shows a weak igniter or a dusty flame sensor on the first cold night. Early fall is the time for a check. For city notes, see heating in Sunnyvale, Santa Clara and Cupertino.