How can I prevent my furnace vent from icing up and shutting off the furnace?
One thing you can do is insulate the exhaust vent all the way to the outlet. The warmer the air is when it gets to the opening, the more likely it won't freeze. Does it pass through any unconditioned spaces on the way to its outlet? If so insulate it the whole way from the furnace as best as you can.. Keep that 85f degree exhaust air as warm as possible on its journey to the freezing cold..