Most homeowners have upgraded their furnaces to high efficiency models.  These typically come with an exhaust exit pipe at the side of the house. During winter with an abundance of snow and very cold temperatures, this exhaust pipe can be buried in snow or severly restricted with a heavy ice build up due to the condensation around the pipe.  If this happens, most furnaces have a sensor that will detect the blockage and shut down, otherwise noxious fumes  will back up into the basement. Having your furnace shut down during the most extreme winter temperatures is an uncomfortable and stressful  experience. It’s important to check both your gas meter and exhaust pipe to clear both of snow and ice buildup.

Recently Manitoba Hydro put out a press release highlighting this very situation. Here it is: