HVAC Emergency Questions, Answered

First check the simple causes: thermostat batteries and settings, the furnace power switch, the breaker, the filter, and snow over the exterior vent pipes.

Usually, yes.

Yes.

Yes.

An HVAC emergency is anything that threatens safety, health, or your home: no heat in winter, any gas smell, suspected carbon monoxide, a major water leak from your system, or no cooling during a heat warning when vulnerable people are home.

Leave the building immediately.

If your carbon monoxide alarm goes off, get everyone — including pets — outside to fresh air first, then call 911 from outside.

There are two shut-offs.

Deal with the house and the people in it first, then the equipment.

Yes, treat it as one.

No.

Put heat and moving air where the plumbing actually runs, keep a thin trickle flowing at the most exposed tap, and open the cabinet doors under sinks on outside walls.

A certified electric heater with tip-over and overheat shut-offs, plugged straight into a wall outlet with a metre of clear space around it, is reasonably safe to run overnight in an occupied room.

Do not dry it out and restart it.

Usually not.

A furnace flame that is yellow or orange and lazy instead of steady blue means the gas is not burning completely, which produces soot and carbon monoxide.

A furnace that smells like exhaust fumes inside the house is spilling flue gas: a vent joint has come apart, an inducer gasket has failed, the vent or chimney is blocked, or exhaust fans are pulling the house negative and back-drafting an appliance.

Carbon monoxide poisoning feels like the flu without the fever: headache, dizziness, nausea, fatigue and confusion.

A red tag on your furnace means a certified gas technician found an unsafe condition and was required by Ontario's gaseous fuels regulation to tag it and notify the gas distributor.

To get your gas turned back on after Enbridge shuts it off, hire a TSSA-registered gas contractor to fix the fault named on the tag.

A gas meter that hisses for a second or two as an appliance fires is usually the regulator beside it adjusting, which is normal.

A house in an Ontario winter gets uncomfortable in a few hours without heat, but pipes take longer.

No.

A furnace that smells like burning plastic or hot electrical insulation usually has an overheating blower motor, a failing capacitor, melted wiring or a scorched control board, or a plastic object has dropped through a floor register into the ductwork.

Smoke coming from a furnace has five usual sources: a blower motor burning out, an electrical short, heavy dust or oil cooking off the heat exchanger, a soot puff from delayed ignition, or flue gases spilling from a blocked vent.

A flame rollout switch keeps tripping because flame or hot combustion gas is escaping the burner box instead of being drawn through the heat exchanger.

If heating pipes or radiators freeze, do not fire the boiler into the frozen loop.

No, do not use your oven to heat your house.

A propane heater is safe indoors only if its rating plate says it is certified for indoor use, it has an oxygen-depletion sensor and a tip-over shut-off, and you run it with a window cracked and a working carbon monoxide alarm.

Any carbon monoxide reading above zero in a house needs an explanation.

A gas fireplace that won't turn off usually has a stuck or shorted wall switch, a remote receiver left in ON or thermostat mode, or, less often, a gas valve stuck open.

A water heater that smells like gas has a leak until proven otherwise: leave the house and call Enbridge Gas at 1-866-763-5427 or 911 from outside, and do not relight, switch or unplug anything on the way out.

A water heater is backdrafting when exhaust spills from the draft hood into the room instead of rising up the vent.

If your water heater floods your basement, stay out of standing water that touches outlets, cords or appliances, and cut power at the panel only if you can reach it dry.

A refrigerant leak in a house is rarely an emergency, but it is not harmless.

Yes, a water heater can explode, but only when two things fail together: the thermostat sticks on and the temperature and pressure (T&P) relief valve is blocked, capped or seized.

If your outdoor AC unit was flooded, do not restart it.