Proper vent termination clearances
It is very important to always ensure there is a proper clearance (>12") between the ground and intake vents. If they are too close to the ground large snowfalls can cause these vents to become blocked. This situation can be potentially dangerous as this can lead to back drafting from combustion appliances and carbon monoxide levels being raised inside the house! If you suspect you may a vent that is too close to the ground contact an HVAC specialist and in the meantime be sure to shovel away any accumulated snow to allow for some clearance around the vent.