Furnace Repair, Heating & HVAC Companies in Ottawa

If you smell gas or a carbon monoxide alarm sounds

Leave first, then call from outside. Enbridge Gas tells Ontario customers who smell gas to get out of the building, leave lights and appliances as they are, keep phones away from the leak, and call its 24-hour emergency line at 1-866-763-5427 or 911. Never assume a neighbour has already called.

A carbon monoxide alarm gets the same answer: go outside and call 911 from a safe distance. CO has no colour and no smell, so the alarm is your warning. It does not detect natural gas, so the smell and the alarm are separate warnings.

Since January 1, 2026, the Ontario Fire Code has required CO alarms next to every sleeping area and on every storey of any home with a fuel-burning appliance. A gas furnace counts.

Three checks before you book a service call

1. Check that the thermostat is set to heat and above the room's current temperature, and change its batteries if it takes them. From the living room, a dead thermostat and a dead furnace feel the same.
2. Look at the filter. Dust restricts the air the furnace can move, and Natural Resources Canada says to change or clean a filter every three months, or sooner once it is loaded. One that has been in since spring is worth ruling out.
3. Go outside and find the vents. Many furnaces vent through pipes in an outside wall instead of a chimney, and TSSA notes that exhaust vents can sit as low as one foot above the ground. A drift, or a snowblower aimed the wrong way, can bury them. TSSA and Enbridge both warn that a blocked exhaust vent lets carbon monoxide build up inside, so clear them with a car brush or a broom, never anything sharp, and keep snow from piling against that wall.

If all three are fine and the house is still getting colder, book the repair and tell the company which checks you have already done.

Signs that need a technician

Natural Resources Canada lists the signs of a combustion problem: soot or staining around the air intake, the burner or the chimney connection; unusual smells, or hot and muggy air around the furnace; and smoke or carbon monoxide alarms going off for no clear reason. Its advice for any of them is to have the system checked by a qualified heating technician.

In Ontario, gas work on a furnace has to be done by a TSSA-registered contractor. TSSA's guidance on finding one is linked lower on this page.

For a shortlist, our guide to HVAC companies in Ottawa ranked by review volume names ten of them and the two licences to ask each one for.

Service it before the first cold night

Natural Resources Canada's minimum for a natural gas or propane furnace is a service at least every two years. Enbridge goes further and recommends a yearly inspection of every fuel-burning appliance by a TSSA-registered contractor. The timing section below explains why September and October are the months to book it.

Furnace repair or replacement: what to weigh before winter

Natural Resources Canada's Heating with Gas booklet gives one number for the decision: replacing a 20-year-old furnace rated at 78 per cent AFUE with one rated at 95 per cent reduces annual energy costs by 18 per cent.

AFUE is the measure NRCan uses for a furnace's efficiency across a whole heating season. A new model's rating is on its EnerGuide label, which the booklet says usually appears on the back page of the manufacturer's brochure.

For a gas furnace to carry the ENERGY STAR symbol, the same booklet requires a condensing unit with an AFUE of 95 per cent or higher and a fan efficiency of two per cent or less. Ask for both numbers on the exact model being quoted.

Repairing an old furnace and upgrading one are separate decisions. NRCan makes the point with blower motors: an efficient retrofit motor can cut a furnace's electricity use, but if the furnace is nearing the end of its service life, the booklet calls that investment probably not a wise choice.

Replacement can change more than the furnace. Many older furnaces share a chimney with the gas water heater, and NRCan notes that keeping the water heater on that chimney after the furnace is replaced may need an approved metal liner, installed by a licensed professional. Ask whether the replacement quote includes it.

The Home Renovation Savings Program pays for heat pumps, at a rate set by how the home is heated now, and an Enbridge gas-heated home qualifies. A gas furnace is not on the program's rebate lists. The heat pump rebate guide linked lower on this page carries the amounts.