Seasonal guides · 4 min read
Most no-heat calls in a Calgary winter turn out to be one of five things a homeowner can check in ten minutes. Here they are in order, and the point at which you should stop checking and pick up the phone.
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A furnace that stops at night in January is not an inconvenience in this city. A house loses heat quickly at minus twenty-five, and the pipes are next.
Before you ring anyone, it is worth ten minutes with a flashlight. A surprising share of overnight callouts end with a technician changing thermostat batteries or flipping a switch, and you pay the callout either way.
If you smell gas or a carbon monoxide alarm is sounding, none of this applies: leave the house first and call from outside.
Work down this list. Each one takes a couple of minutes and needs no tools.
The thermostat
Set to Heat, not Cool or Off, with the target a few degrees above the room. Replace the batteries even if the screen looks fine — a weak battery can fail to send the call for heat long before the display goes blank.
The furnace switch and breaker
Next to the furnace there is a switch that looks exactly like a light switch. It gets flipped off by mistake more often than anything else on this list. Check the breaker for the furnace in the panel too.
The front panel
Furnaces have a safety switch that keeps them off while the lower door is loose. If someone changed the filter recently, push the panel firmly back into place.
The filter
A filter clogged with dust starves the furnace of air, it overheats, and a safety limit shuts it down. That looks exactly like a broken furnace. If you hold the filter up to a light and cannot see through it, replace it.
The vent pipes outside
A high-efficiency furnace has two plastic pipes through an outside wall. Drifting snow or frost can block them in a storm, and the furnace will refuse to fire until they are clear. Clear them by hand, gently.
Most furnaces made in the last twenty years report their own fault.
The blinking light
Behind a small window in the lower panel is a status light that blinks in a pattern. The pattern is decoded on a label inside the door. Write it down before you call — it tells a technician what to bring.
Gurgling, then nothing
High-efficiency furnaces drain water through a small plastic line. In a cold snap that line can freeze where it runs to the floor drain or outside, and the furnace shuts itself off. If you hear gurgling, mention it when you call.
Fan running, air cold
If the thermostat fan is set to On rather than Auto, it blows room-temperature air between heating cycles and nothing is wrong. If it is on Auto and the air is still cold, the burner is not lighting — that one needs a technician.
Do not try to relight, bypass or reset anything on the gas side of the furnace beyond the steps above. Any work on the gas valve, burners or venting must be done by a certified gas fitter in Alberta.
If the five checks did not fix it, these decide how urgent it is.
Call now, overnight if needed
The house is cooling toward freezing, someone at home is elderly, very young or unwell, or the furnace is short-cycling — firing and shutting off every minute or two.
It can wait for the morning
The house is holding above about 15°C, nobody is vulnerable, and you have a safe way to keep one room warm. Daytime rates are usually lower than overnight callout charges.
While you wait
Open cabinet doors under sinks on outside walls, keep interior doors open so heat spreads, and let a cold tap drip if the house is dropping fast. Never use a gas oven or barbecue to heat the house.
Three questions that save money and misunderstandings at midnight:
These lists are built from what each firm states on its own website, so they are who says they do the work rather than our recommendation of who does it best.