The vent is outside. The danger is inside.
TSSA and Enbridge Gas warn every winter about buried exhaust vents and gas meters. Here is what to clear, how to clear it, and the four things you must never do.
Licensed technicians
Quick answer
A furnace vent blocked by snow has to be cleared, and it has to be cleared gently. Use a brush or a broom. Never kick the pipe, never scrape it with anything sharp, and never pile shovelled or blown snow against it. Check the gas meter at the same time, because the same storm buries both.
Key takeaways
- A furnace vent blocked by snow happens "without a homeowner's knowledge," TSSA warns, during shovelling, snowblowing or heavy snowfall.
- Enbridge Gas: "you can remove the snow carefully with a brush or broom."
- Enbridge Gas: "Never kick your gas meter or vent pipes to clear ice and snow."
- Clear the icicles above the vent too, because meltwater refreezes on the pipe below.
- If you cannot clear the ice yourself, Enbridge Gas asks you to call 1-866-763-5427.
What the pipe on your wall is doing
Walk around a house built or re-equipped in the last twenty-five years and you will find one or two plastic pipes coming out of a side wall, usually low down.
That is the furnace venting. A high-efficiency furnace does not use the old chimney. It pushes its exhaust out through the wall and, in most installations, draws its combustion air back in beside it.
Both ends matter. Exhaust has to leave, and air has to arrive. Snow that covers either one is interfering with how the appliance burns gas.
Water heaters, fireplaces and other fuel-burning appliances vent the same way. TSSA's advice covers all of them, not just the furnace.
How a furnace vent blocked by snow goes unnoticed
This is the part that catches people out, and TSSA names it directly.
Sam Sadeghi, Director of Fuels Safety at TSSA, warns that vents block "without a homeowner's knowledge." He points at three everyday causes: shovelling, snowblowing and heavy snowfall.
Think about how that happens on an ordinary Thornton driveway. You clear the drive and throw the snow against the house, because that is where there is room. The pile reaches the vent by February.
Drifting does the rest. Wind pushes snow into the lee of the building, which is exactly where vents tend to sit.
Then there is ice. Water runs off the roof, drips from the eaves above, and refreezes on the pipe. Enbridge Gas specifically asks homeowners to clear icicles from overhead eaves troughs for this reason.
How to clear it, and the four things never to do
The method matters more than people expect, because the vent is thin plastic and the meter is a pressure-carrying fitting.
Enbridge Gas puts the safe method plainly. "You can remove the snow carefully with a brush or broom."
That is it. A soft brush, a broom, your gloved hand. Work the snow away from the opening rather than packing it in.
| Do | Never | Why it matters |
|---|---|---|
| Brush or sweep snow away | Kick the pipe or the meter | Enbridge Gas: "Never kick your gas meter or vent pipes" |
| Clear by hand, gently | Scrape with anything sharp | It "may cause unintended damage" |
| Throw snow away from the wall | Shovel, plow or blow snow against it | Burying it is what caused the problem |
| Steer the snowblower wide | Bump the meter with the machine | Enbridge Gas asks you to be careful of this |
| Knock down icicles above | Leave melt dripping onto the pipe | It refreezes on the vent below |
If the ice has set hard and will not brush off, stop. Enbridge Gas is direct about the next step. "If you suspect a problem or cannot remove the ice yourself, call us at 1-866-763-5427."
Carbon monoxide is the reason this matters
A blocked vent is not a comfort problem. It is a combustion problem, and the product of incomplete combustion is carbon monoxide, which you cannot see or smell.
TSSA's Sam Sadeghi says it is "important for homeowners to be able to recognize the symptoms of CO poisoning," and asks people to "install and test certified CO alarms."
Ontario law already requires those alarms in most homes. Our guide to the carbon monoxide alarm rules covers where they go and how many you need.
If an alarm sounds, leave the house and call 9-1-1 or the fire department from outside. Do not stay indoors to look for the source.
The gas meter is the other half of the job
While you are out there, look at the meter. The same joint warning from Enbridge Gas and TSSA covers both.
Snow and ice around a meter can damage it, and the regulator vent on it needs to stay clear. The rules match those for the exhaust pipe. Brush, do not scrape. Sweep, do not kick.
Snowblowers deserve particular care here. A meter sits at roughly the height of an auger housing, and a bump that looks minor can do real damage.
What this means around Thornton
Thornton sits in open Essa Township country, and open country means drifting. Snow does not simply fall here, it travels, and it stacks against whatever stands in its way.
Plowed roads add a second problem. A plough leaves a windrow at the end of a rural driveway. That snow has to go somewhere, and the side of the house is often the nearest place with room.
So a furnace vent blocked by snow is more common here than in town. Our advice to customers around Thornton and Essa is a short walk after every real snowfall. Check the vent, check the meter, and look up at the eaves above both.
It takes two minutes, and it is the cheapest safety check you will do all winter.
If the furnace has already stopped
A furnace that quits during or just after a storm deserves a look outside before anything else.
Go and find the vent. A furnace vent blocked by snow or glazed with ice is where to start. Brushing it clear is work you can do yourself.
If the furnace still will not run once the vent is clear, leave it alone. Call for furnace repair instead. A furnace that shuts itself down has usually done so on purpose.
Do not restart it over and over to see what happens, and do not remove panels to improve the airflow. Both of those turn a service call into something worse.
Talk to Aire One Barrie
If your vent is iced, your furnace has stopped, or you simply want the venting checked before the snow arrives, we can help. We cover Thornton, Essa Township and the rest of Simcoe County from our Barrie shop.
- 24/7 emergency service, including weekends and holidays
- Venting and combustion checked as part of a furnace service
- Upfront pricing before the work starts
- Bonded, factory trained and licensed technicians
Frequently asked questions
What happens if my furnace vent is blocked by snow?
The exhaust cannot leave and the combustion air cannot arrive. The appliance then stops burning gas the way it should. That raises the risk of carbon monoxide indoors, which is why TSSA and Enbridge Gas repeat this warning every winter.
How do I safely clear snow off a furnace vent?
Enbridge Gas says you can remove the snow carefully with a brush or broom. Work the snow away from the opening and clear the icicles above it. Never use anything sharp or hard on the pipe.
Can I kick or chip the ice off a vent pipe or gas meter?
No. Enbridge Gas says never to kick a gas meter or vent pipe to clear ice and snow. It also says not to scrape them with a sharp instrument, because that may cause unintended damage.
Where should I put the snow from my driveway?
Anywhere except against the wall where the vent and meter are. Enbridge Gas asks homeowners not to shovel, plow or blow snow up against the meter or vent pipe. It also asks you to be careful not to bump the meter with a snow blower.
Who do I call if the ice will not come off?
Enbridge Gas asks you to call 1-866-763-5427 if you suspect a problem or cannot remove the ice yourself. If a carbon monoxide alarm is sounding, leave the house first and call 9-1-1 or the fire department from outside.
Sources
- TSSA and Enbridge Gas, Caution Homeowners to Keep Gas Meters and Fuel-Burning Appliance Vents Free from Snow and Ice — blockage without a homeowner's knowledge, and CO alarms.
- Enbridge Gas public service announcement, February 14, 2025 — the brush or broom method, what never to do, and the 1-866-763-5427 number.
