Furnace Won’t Switch On? Here’s What Might be Happening

Having trouble with your heating system? When a furnace won’t switch on, the problem may begin at the thermostat, involve the electrical supply or occur during the furnace’s startup sequence.

Is the furnace completely silent? Does a small fan start? Do you hear clicking without any heat following? Those details help us distinguish a system receiving no heating request from one attempting to start but unable to complete the process.

It Could be a Thermostat Problem

The thermostat tells the furnace when heat is needed. If it is set to cooling, switched off or set below the current room temperature, it will not signal the system to produce heat.

Check that it is set to “Heat” and that the target temperature is above the displayed room temperature. A programmed schedule may also be setting a lower temperature than expected.

For thermostats that use replaceable batteries, depleted batteries can interfere with operation. Other models receive power from the heating system, so a blank display may point to a power problem rather than a battery issue.

If the settings are correct, a thermostat or wiring fault may still prevent the heating request from reaching the furnace.

It Could be an Electrical Power Problem

A gas furnace needs electricity as well as gas to function. Its controls, ignition system and motors cannot operate normally without electrical power.

An accidentally switched-off furnace service switch, a power outage or a tripped breaker can leave the equipment unresponsive. Some furnaces also have a door safety switch that interrupts operation when the access panel is not properly seated.

You can check whether the furnace’s external service switch has been turned off and whether other equipment has lost power. Leave internal electrical testing to a technician.

It Could be an Ignition Fault or Safety Shutdown

A furnace may receive the thermostat’s request and have power but still fail to produce heat. Startup happens in stages, with safety checks before the burners can operate.

A failed ignitor can prevent the gas from lighting. A gas supply problem can prevent fuel from reaching the burners. Venting problems or other conditions detected by safety controls may stop the sequence before ignition.

If the burners light briefly and then go out, flame detection is another possibility. A dirty or faulty flame sensor can prevent the furnace from confirming that a flame is present, causing it to shut off the gas.

Call Hydro-Flo for Furnace Repair in Edmonton

If your furnace is showing an error code, write it down and let us know when you call for furnace repair in Edmonton. Let’s get the hot air flowing again!