Thermostat Not Working

A thermostat fault can leave working equipment idle or stuck running, so it's worth a call to find out which side of the wiring actually failed.

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When this becomes an emergency

The screen has gone dark and pressing buttons does nothing at all.
The heat runs continuously and won't shut off at the set point.
The display shows a temperature that clearly doesn't match how the room feels.
The thermostat has been replaced recently and the heat has behaved oddly ever since.

What a pro does

Heat that won't shut off is as much a thermostat symptom as heat that won't start. A shorted wire, a stuck relay, or a control fault can hold the heat circuit closed, so a tech isolates the thermostat from the equipment and watches what the furnace or boiler does on its own. Recent replacements get scrutiny of their own, since a wire landed on the wrong terminal produces exactly this behavior and is easy to do on an older system where the wire colors don't follow modern convention. Beyond that it's power supply, the low-voltage run, and where the thermostat is mounted.

Frequently asked questions

Why would the heat run constantly instead of shutting off?

Something is holding the circuit closed, whether that's a shorted wire, a stuck relay, or a fault at the thermostat itself, and the equipment simply keeps doing what it's being told.

Are wire colors on an old system reliable?

Not particularly. Older installations often used whatever cable was on hand, so terminal position matters far more than what color the wire happens to be.

Can a thermostat cause a boiler and a furnace to behave differently?

The wiring conventions differ between system types, which is one reason a swap that seems straightforward on paper can go sideways on hydronic equipment.

Does a dark screen always mean the thermostat is dead?

No. It can just as easily be a blown fuse on the control board or a break in the low-voltage wire feeding it power.

Thermostat Not Working?

Get connected with a local pro now.

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