First and foremost your filters you be changed at least twice a year. When filters get soild your furnace or air conditioner has to work so much harder to attain the desired temperature of the thermostat. Plus it prolongs the life of your equipment. It also results in way more energy usage. This is money you could save and spend on something for yourself. If your filters get caked with soil the furnace will overheat and it will go to a very high temperature and shut off by the limit control. If this is the case you can tell by feeling the ducts. If they are so hot from a soft touch the limit is cycling the furnace.
Most high efficient furnace 90% or more are vented by either 2 or 3” plastic pipe probably vented horizontally through sidewall of home. They are pitched back to the furnace so extra condensate runs back through the drain. They are terminated by a 90 degree elbow outside that is either turned up or down. Usually these are two pipe systems. One for the combustion air intake that comes in on top of furnace and the other is for exhaust. Outside the 90 elbow that is turned down is the combustion air and the elbow turned up with a little smoke and water vapor coming out is the exhaust. When we get snow or high winds sometimes this will build up around the intake and this will immeadiately shut down the furnace. I would suggest during periods of moderate to high snow falls make sure it is cleared out around the intake. I have seen where tennis balls, rodents, or small kids top will be stuck in these. One of the most common questions that is asked, can we put a metal screen around intake or exhaust. You can not because ice will crystalize around the metal and will shut the furnace down.
Call your HVAC specialist and sign up for a maintenance agreement. Typically they will come out in spring and in fall. Treat your HVAC machine like a automobile. The more it is maintained and serviced the more you prolong the life. You are also treated as a priority customer so when it is 95 or below zero you get service immediately. This service will pay for itself in the energy saved. It will also give you piece of mind because at extreme temperatures it is very unlikely you will be calling for service.
