Homeowners often buy the filter size that their system came equipped with without noticing the merv or thickness rating of the filter. While it is true that a thicker, higher merv filter will capture more dust particles these filters are one of the main reasons why major breakdowns happen on a furnace. These very thick filters put a high amount of strain on the furnace because air passing through the filter into the furnace becomes greatly restricted due to the thickness of the filter. This causes increased strain on the major motors in the furnace and also causes the furnace interior to run hotter than the manufacturer’s specifications. An overheating furnace experiences the accelerated deterioration of the furnace heat exchanger and when the furnace gets too hot the safety switch in the unit will continuously turn the furnace on and off.

It is recommended that basic, non-restrictive fiberglass filters are used so the system can breathe and operate properly. This creates prolonged equipment life and better heating and cooling distribution evenly throughout the home even in a 2-story home. If allergies or dust particles are a problem in a home installing a non-restrictive media filter or an electrostatic filter in conjunction with an air purifier is a more effective solution for alleviating these issues while not damaging your equipment.