The filter is a big factor in your indoor air quality and how well your furnace operates.
As the filter collects various bits of airborne debris, it starts to clog up. After a while, that build
up makes it very difficult for air to pass through. That means the
blower is working harder, increasing your energy bills, taking longer to
heat your home, and risking burning out the blower motor.
best way to know how often you need to change your air filter is by
simply checking it on a regular basis. Every furnace heats a different
home, with different factors that affect a filter’s life span. After a
while, you will develop a good idea of how quickly contaminants build up
on your filter and how often you will need to install a replacement.