Think twice about using high merv air filters!

When shopping for an air filter, many people will opt for the ones that say they remove allergens, pet dander, odors, etc. The issue with these is that they are too restrictive for most hvac systems. Each system from the factory has a rating on how much static pressure they can have before starting to drop in performance. You can find this rating in the label on your air handler/furnace. Lets say its rated for .2" of water column like in a typical Carrier. Evaporator coils, ductwork & filters will all add resistance to the system which will raise static pressure. If you are going to use a high merv filter then the filter alone will usually exceed what the system is rated for as far as resistance. The higher you go over that .2" of W.C mark, the less air your system will move. Many filters will have a chart that shows the amount of resistance a particular filter will cause at a certain cfm. Just note this number is for a clean filter, it will rise as the filter starts to get dirty.