Solving the Reduced Airflow Problem
Pleated air filters work great for reducing allergens in your home. But when homeowners leave them in too long, they clog. The reduced airflow causes overheating and burner shutdown. If that happens too many times, the "limitswitch" fails and then the furnace won't fire up at all. The service call and new part can easily cost you $175
No filter manufacturer can predict how long its filters will last because none of them know the dust conditions in your home So you have to check it often. The rule of thumb is, "If it looks dirty, it is dirty." If you want a smarter way to determine when it needs replacing, install an air filter gauge (General G-99 Air Filter Gauge Kit; about $16 through our affiliation with amazon.com
). It measures airflow between the filter and the furnace via a small hose.