The short answer
ClearSky repairs standard and high-efficiency gas furnaces and electric furnaces in Cupertino, including condensate, ignition, blower and venting problems. Current Air District rules do not require replacing a working furnace, so repair is often the right call.
Cupertino furnaces live in some awkward places: tucked into a hall closet, hung sideways in an attic above the bedrooms, or squeezed into a corner of the garage behind the bikes. Wherever yours sits, it probably goes months without much attention, then has to perform on the first cold, wet week of the season. ClearSky Heating & Cooling repairs furnaces throughout Cupertino and the 95014 area, eight miles southwest of our San Jose base. We work on standard and high-efficiency gas furnaces as well as electric furnaces and air handlers, and every visit includes a check of combustion safety and venting, not just the part that broke.
Standard or high-efficiency: why it changes the repair
It helps to know which kind of gas furnace you own. A standard efficiency furnace vents hot exhaust through a metal flue pipe, often up through the roof. A high-efficiency condensing furnace pulls so much heat from its exhaust that water condenses inside it; those units vent through white plastic pipe and drain water through a small trap and hose.
Condensing furnaces bring their own failure points. A clogged condensate trap or a kinked drain hose can stop the furnace cold, because the pressure switch will not let it fire while water backs up. A plastic vent that has sagged can collect water too. Standard furnaces, on the other hand, are more prone to draft and flue issues, and their metal vent connectors need to stay sealed and sloped correctly.
- Gurgling sound before shutdown: water backing up in a condensing furnace's trap or vent
- Water under an attic furnace: drain hose, trap or secondary pan problem, worth fixing quickly to protect the ceiling
- Furnace tries to start three times and locks out: often ignition, flame sensing or a pressure switch fault
- Rust flakes or scorch marks near the burners: venting or combustion problem that needs inspection
Attic furnaces in two-story homes
Many larger Cupertino houses place the furnace in the attic, where it can serve the upper floor directly. That arrangement is efficient, but it also means a small drain or burner problem can go unnoticed until it causes a stain on the ceiling below. Attic units also deal with temperature extremes; summer heat in the attic is hard on wiring, control boards and the rubber hoses connected to pressure switches.
When we service an attic furnace, we check the secondary drain pan and float switch, confirm the platform and access path are safe, and look for chafed wires or brittle hoses. If the furnace is hard to reach, we will also tell you if access improvements would make future service easier and safer.
Electric furnaces and air handlers
Some homes heat with electric resistance, either through an electric furnace or heat strips inside a heat pump air handler. Typical repairs include burned-out heating elements, failed sequencers or relays, tripped high-limit switches and weak blower motors. We test each element and its controls with a meter, because one dead element can quietly reduce your heat output without shutting the system down.
Repair now, plan later, or replace
Most furnace calls end with a repair: a flame sensor, igniter, pressure switch, inducer motor, blower capacitor or control board. When a furnace is older, we also give you an honest read on its overall condition so you can plan instead of reacting.
There is no rule forcing you out of a working gas furnace. The Bay Area Air District appliance rules apply only when an existing furnace fails or is replaced. Looking further ahead, Rule 9-4 requires gas furnaces manufactured from 2029 to meet a zero-NOx standard, which in practice points homeowners toward heat pumps at that point. If your furnace is near the end of its life, it may make sense to repair it now and plan a heat pump conversion for a convenient time. BayREN and your local clean energy provider list current incentives; offers change with each funding cycle.
Cupertino and the surrounding towns
We repair furnaces across Cupertino and in neighboring Saratoga, Los Altos, Sunnyvale, Santa Clara and Campbell. Homes on the western edge of the valley near the hills can see colder overnight temperatures than those closer to the Bay, so their furnaces often carry more of the winter load.
Gas smell in the house? Leave first and call your gas utility from outside. Carbon monoxide alarm sounding? Get everyone outdoors and call emergency services. Repairs come after the home is safe.
More services in Cupertino
- AC Repair in Cupertino
- Heating Repair in Cupertino
- Heat Pump Installation in Cupertino
- AC Installation in Cupertino