citynews:
Deputy Fire Chief Larry Cocco with Toronto Fire Services says it’s imperative to clean snow and ice buildup around your furnace vents.
“A lot of homes are heated with natural gas and more modern furnaces and gas-fired appliances, or what they call direct vent. They’re no longer venting up a chimney that goes through the roof. They’re actually vented through the side of your home in a small vent. There are two purposes of it – it brings in clean fresh air to allow combustion. It also allows the combustion gases to be removed from your home,” says Cocco.
https://toronto.citynews.ca/2022/01/17/ontario-storm-frozen-furnace-pipes/
https://globalnews.ca/news/4907531/what-to-do-about-snow-and-ice-build-up-around-furnace-vents/