Furnace Not Heating in Woodside

Furnace Not Heating in Woodside

A furnace that won't make heat is, in the great majority of cases, one fixable part: a cracked hot surface igniter, a flame sensor glazed with carbon, a high-limit switch tripped by a choked filter, or a control board that dropped a relay. None of that means the system is done. In Woodside the diagnosis often turns on how the property is set up, because many estates here carry more than one heating system covering the main house, a guest house, and sometimes a pool house.

These properties sit up in the wooded hills off Mountain Home Road and Kings Mountain Road, and the shaded, canyon-facing sections run cooler through the winter than the open parts of the lot, so a marginal furnace works harder wherever it serves those spaces. When a homeowner tells us the furnace isn't heating, it usually turns out one of several systems has failed, often the one covering a guest house or a shaded wing. A single dead system narrows the search fast: the fault is in that unit or its controls, not the gas service or a shared thermostat platform.

Where the systems on a property are different ages, the failure could be an igniter on the older main-house furnace or a drifting board on a newer unit installed for the guest house. The long private driveways and gate codes on these properties also mean we plan the visit ahead of time so access isn't the thing that delays the repair.

Common causes

One system down on a multi-building property. When the guest house or pool house goes cold while the main residence stays warm, the fault is almost always contained to that separate system. We identify the unit serving the affected building and diagnose it directly, leaving the others alone.

Cracked hot surface igniter. The most common no-light failure on a forced-air furnace. Years of heat cycling crack the ceramic element and it stops glowing. We provide a written repair estimate after the on-site diagnosis and before any work starts. The older unit on the property, often the one serving the main house, is usually first to go.

Dirty flame sensor. If a system lights and then drops out a few seconds later, the flame sensor is carboned over and the board can't confirm flame, so it cuts the gas. This shows up more on a unit that runs less, like one serving a guest house that sits empty part of the year. We provide a written repair estimate after the on-site diagnosis and before any work starts.

Stuck zone damper. On a property with a zoned system across the main house, a damper that won't open leaves one section feeling unheated even though the furnace is firing fine. We test the damper motors and zone panel to separate a distribution problem from an actual heat-production problem.

Limit switch tripped by a dirty filter. A neglected filter on one of the property's several systems starves airflow, overheats the heat exchanger, and trips the high-limit switch. We confirm filter condition and airflow, and check whether the limit reset on its own or failed closed.

Control or zone board fault. Where systems on a property age at different rates, a heat relay or zone board can fail and leave one unit unable to deliver heat. We meter the board's outputs before condemning it, since boards are among the more expensive furnace parts.

How we diagnose it

• Identify which system on the property serves the cold building or wing and isolate the diagnosis to that unit.
• We separate a heat-production fault from a distribution fault by testing the zone dampers and zone panel.
• The full ignition sequence gets run, and we meter the igniter, flame sensor, and limit switch on the affected furnace.
• Control and zone board outputs get tested before we condemn an expensive board.
• We meter carbon monoxide and inspect the affected system's heat exchanger before we leave.

$99 diagnostic, credited toward the repair. You get a written quote before any work begins.

Furnace Not Heating in Woodside: common questions

Nearby and related

Furnace Not Heating near Woodside: Portola Valley · Hillsborough · Menlo Park .

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