What to do if your furnace stops working


Even if it’s -30 C, don’t panic! Just do these five things

It’s 10 o’clock at night and -30 C, not counting the windchill. Do you know what you’d do if your furnace stopped working?

“Freeze” is the wrong answer.

1. Turn on your thermostat

thermostat malfunctioning

“Come on,” I say, when Weran tells me to make sure the furnace is on. What kind of tip is that?

A good one, it turns out. “I ask people [who call me] on the phone all the time and it’s in the off position. It’s a thing. It really is,” he says. “You want to make sure that it is in the on position, that it’s turned up and calling for heat.”

2. Check whether there’s power

electrical switch for furnace

We all know that most furnaces won’t work without natural gas, but they need electricity, too, which runs parts such as the blower motor that pushes air through the ducts.

In addition to the breaker, “There should be a switch on the wall or ceiling nearby,” says Weran. Make sure that switch is on. Then, if “the blower motor is on, but it’s blowing cold air, you know that it has power.” So, keep investigating.

3. Unblock the vents

icy furnace vents

Modern furnaces have two pipes leading outside. One is exhaust, the other is air intake. If the former is blocked, bad things like carbon monoxide may not be properly vented (make sure there’s a CO detector on every floor of your home, Weran adds, including in the room that contains your furnace).

If the intake is blocked, the furnace will simply shut down. Fish around inside both pipes to keep them free of snow, ice or another other debris, says Weran.

4. Change your filter

Common, one-inch-thick filters should be changed every three months, says Weran (five- and six-inch varieties can last six months).

The filter’s job is to clean air before it enters the furnace; over time, it fills with dirt and debris. Too much, and it becomes “like cardboard,” says Weran, preventing fresh air from entering. As a result, the furnace gets too hot, tripping a safety sensor that shuts everything down.

5. Get someone to take a look – but not just anyone


“If those four things are good, then you’re probably going to have to call a service tech, because then we’re getting into an internal problem.”

No matter what, he stresses, every charge on a bill should be clearly accounted for.

“You need training when you’re dealing with a gas appliance.”

Whatever you do, don’t open up your furnace on your own and start nosing around. “You need training when you’re dealing with a gas appliance,” . “If you do something wrong, you could cause a real hazard.”


Get a free quote


Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.