Furnace Not Turning On? 7 Things to Check Before You Call

1. Check the thermostat

It sounds obvious, but a surprising number of no-heat calls come down to the thermostat. Make sure it's set to Heat, the set temperature is above the current room temperature, and the batteries aren't dead. Smart thermostats can lose Wi-Fi or get stuck on a schedule, so try raising the temperature manually.

2. Check the breaker and furnace switch

Your furnace has a power switch that often looks like a light switch on the wall or the side of the unit. Make sure it's on. Then look at your electrical panel for a tripped breaker labelled furnace. Reset it once — if it trips again, stop and call a technician.

3. Replace a clogged filter

A dirty filter restricts airflow and can cause the furnace to overheat and shut itself off as a safety measure. In Toronto homes we recommend checking 1-inch filters monthly in winter and replacing them every one to three months. Thicker media filters last longer.

4. Make sure the furnace door is closed

Furnaces have a safety switch on the blower door. If the panel isn't seated properly after you change a filter, the furnace won't run.

5. Check vents and intake pipes

High-efficiency furnaces vent through white PVC pipes on the side of the house. After a heavy snowfall or ice storm, these can get blocked. Gently clear snow and ice from around the pipes without damaging them.

6. Look at the status light

Most modern furnaces have a small window with a blinking LED. The blink pattern is a code — the chart is usually on the inside of the door. Write down the pattern before you call; it helps our technician bring the right part.

7. Know when to stop

If you smell gas, leave the home and call Enbridge Gas or 911. If your carbon monoxide alarm sounds, get everyone out and call 911. Otherwise, if these checks don't solve it, call us at 647-371-0340. We offer same-day furnace repair across Toronto, North York, Scarborough and Etobicoke, and we'll give you an upfront price before any work begins.

Regular furnace maintenance catches most of these problems before they leave you without heat. A fall tune-up includes cleaning the flame sensor, testing safety switches, inspecting the heat exchanger and checking venting — the exact things that cause most mid-winter breakdowns.