Your furnace died in winter. What to do next
A furnace that stops in January is stressful and it is rarely an emergency in the dangerous sense. Here is the order to do things in, including the two checks that fix it often enough to be worth ninety seconds.
First, the one thing that is actually urgent
If you smell gas, or your carbon monoxide alarm is sounding, leave the house and call your gas utility or 911 from outside. Do not investigate it, do not open windows first, and do not wait to see whether it stops. Everything else on this page can wait until you are outside and safe.
Two checks worth ninety seconds
Check the thermostat is calling for heat and its batteries are not dead, which is a more common cause than people expect. Then check the furnace switch, which looks like a light switch on or near the unit and gets turned off by accident, and the breaker. If the furnace has a sight glass or status light, note the blink pattern before you call: it is a diagnostic code and it will save the technician time.
Keeping the house safe while you wait
The real risk in an unheated Ontario house is frozen pipes, not discomfort. Open the cabinet doors under sinks on exterior walls, let a cold tap run at a trickle, and keep the house closed up rather than opening it. If it is going to be many hours, turning off the water supply and draining the lines is worth considering. Never use an oven or a barbecue for heat.
What to have ready when you call
The make and model off the label on the unit, roughly how old it is, what it is doing or not doing, any blink code, and whether it is under warranty or on a service plan. That handful of facts is usually the difference between a technician arriving with the part and arriving to look at it.
Repair or replace
A furnace past fifteen years old, facing a repair worth a meaningful fraction of a replacement, is usually not worth repairing, and a technician who tells you that on a cold day is worth keeping. Under about ten years, repair is normally the right call. In between it depends on the part, and anybody who answers that question before seeing the unit is guessing.
What a replacement actually looks like
Same-week installation is normal outside a cold snap and gets harder during one, which is when everybody’s furnace fails at once. You should be told a real date rather than a promise, the price should be all-in before anyone books, and nothing should be due before the work is done. If you are being asked to decide in the next ten minutes, that urgency is a sales technique rather than a fact about furnaces.