According to a press release, the firefighters got to the residence just before 9:00 a.m. Sunday. They found the entire west side of the house blocked with snow, causing the furnace to stall.
The Suamico Fire Department dug out the vent.
This is why the SFD says it's so important to keep vents clear:
Suamico Fire Department reminds you that if either the air-intake or the exhaust vent becomes blocked by snow the system will stall, either because it will be starved of oxygen, or because its built-in safety mechanism will shut it off. If the blockage is in the air intake the system will shut down, and the property will cool down until the blockage is removed and the system can be re-fired. But if the exhaust vent is covered by snow, the problem can be more worrying. The blockage might be enough to cause the system to shut down, but before that happens a snow ‘cave’ can be formed around the vent trapping the exhaust fumes – including the CO – and forcing them back into the property through cracks in the building itself. CO is odorless, colorless, and tasteless, but in sufficient concentration can be harmful to people and animals. For this reason it is vitally important to keep your exhaust vent clear.
If you don’t know where your system vents, the easiest way to find out is to look at the boiler or furnace. If it’s an older system venting to the chimney, you’ll see an aluminum pipe coming off the back of the furnace. If it’s a newer system, there’ll be two 3”-diameter PVC pipes coming off the top – one’s the air-intake, the other the exhaust – follow those pipes and you’ll see where they exit the building.