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Why Won’t My Furnace Turn On?

Having heating trouble?

We offer fast furnace repairs.


The last few weeks have proved that the chilly weather has arrived for the rest of the year here in Massachusetts. If you’re like most homeowners in the area, you recently turned your furnace on for the first time in months. How did it run when you first switched that thermostat to heating mode? Does it seem to have trouble turning on, or did it only stay on for a few moments?

We talk to many homeowners who kick on their heating systems for the first time in the fall, only to find that some problem is keeping their system from running as it should. In case you’re having trouble with your furnace this season, we wanted to share the most common causes of furnace issues.

Improper Thermostat Settings

It may sound silly, but you’d be surprised at how often we show up for a furnace repair, only to find that the thermostat was set incorrectly! Double check that your thermostat is indeed in heating mode and not cooling mode, and be sure that it has working batteries.

Delayed Start-up

Some people assume that if the furnace doesn’t kick on within a minute of turning on the heat, that something must be wrong. However, furnaces have a normal time delay of one to two minutes. This is because the air plenum has to heat up before the fan will turn on.

Tripped Circuit Breaker

Even natural gas furnaces have electrical components such as the ignition system and fan. Check your breaker box for a tripped circuit breaker. If the furnace’s breaker is in the middle position, turn it fully into the off position and then back into the on position.

No Pilot Light

Older furnaces use a continually burning flame known as the pilot light to ignite the gas. Sometimes a nearby draft or malfunctioning thermocouple can cause this flame to go out. If you have an older furnace with a pilot light, try lighting the pilot light with a match. If that doesn’t resolve the issue, it’s likely time for a furnace repair.

Insufficient Gas Supply

Gas furnaces need a sufficient supply of gas in order to turn on. Make sure the gas valve is turned fully on. (Some homeowners forget that they’ve partially turned the valve off for safety reasons.)

Safety Features

Furnaces have built-in safety features to prevent overheating, natural gas leakage into the home, and other issues. For example, the pilot sensor shuts off the gas supply when it doesn’t detect a pilot light. The limit switch, meanwhile, turns the furnace off when it detects that the heat exchanger is overheating.

If your furnace won’t turn on, it could be that one of these safety switches has kicked in — or one of them is malfunctioning.

Let Kearney HVAC Diagnose Your Furnace

If your furnace seems to have trouble turning on or staying on, talk to the heating experts at Kearney HVAC. We’ll be there to resolve the issue as quickly as possible, and we stock our trucks with common parts so we can repair your furnace in just one visit.

Furnace won’t stay on? Call 978-388-0845or contact us today to schedule your heating repair!