Furnace won't start? Five checks for a Nepean cold snap

When the temperature drops overnight, a furnace that has been fine all fall can stop. Some causes are easy to fix yourself. Go through these in order.

1. The thermostat

Set it to Heat and turn it up past the current room temperature. A blank or faint display usually means flat batteries, so swap them.

2. The furnace switch

Near the furnace there's a switch that looks like a light switch. It's easy to flick off by mistake. Check it's on, and check the breaker for the furnace in your electrical panel.

3. The filter

A clogged filter chokes the airflow, and the furnace may trip its high-limit switch and stop. Slide it out. If it's grey and clogged, put in a new one of the same size.

4. The front panel

Most furnaces won't run if the front door isn't fully closed. Push it firmly into place.

5. The status light

Many furnaces have a small light behind a window in the panel that blinks a code. Note how many times it blinks. The code chart is usually on the inside of the door, and it helps the technician.

When to call

If the heat still isn't on after these checks, call us at (613) 706-4872. If you ever smell gas, get everyone outside first, then call your gas company's emergency line. See furnace repair for what we fix.