When Is it Time to Replace my Furnace Filter?

Many home owners are somewhat confused when it comes to how often they should replace their furnace filters. The average manufacturer’s guideline is every 90 days, or three months. This is a fairly good recommendation for most filter systems and homes, but in reality there are a lot of factors that can make a big difference in how often it is truly necessary to change them. The main focus should be placed on the family’s health and the efficiency of the furnace. HVAC contractors like Bell Brothers will often recommend a reusable filter. Reusable filters are great, you simply wash and reuse.


Everyone wants their furnace to run efficiently in order to keep your house warm and lower heating bills. Clean filters will help one achieve this. A trusted telltale sign that it is time to change the furnace filters is when you see dust piling up on the furniture surfaces. You may even notice dust particles floating in the air around the vents when the system is running, or a musty smell of dirt and dust. Is the furnace turning on and off more often than normally? This is a red flag that the filters are clogged and not allowing the unit to function properly. Filters should actually be pulled out at least once a month and checked. Look for signs of discoloration or layers of dust and dirt. You will eventually notice a regular pattern of how often they need changing. One definite time to change the furnace filters is at the start of the heating season. This job should be a part of the annual fall routine for home owners.


Homes where the residents suffer from breathing problems will need their furnace filters changed more often. Those with asthma, allergy sufferers, or COPD patients in the house will notice these family members having clogged nasal passages when the filters are dirty. It is essential to change the filters more often in these situations. Homes with pets will also realize their filters need more frequent changing. Pet dander can get stuck within the dirty furnace filter and end up being recycled throughout the house. This can lead to cold like symptoms for those living in the home.

Setting up a Routine

Once you have done a monthly check of your furnace filters in your home for a full year, you will be able to have a better sense of when to change them. Every house is different, so it is hard to set a standard replacement timeline that will work for all homes. Homes with pets will need the furnace filters replaced more often. Those with large homes will find it needs done less often, due to the fact that there is more room for the air to circulate than in a smaller house. No matter what your situation is, routinely changing the furnace filters will leave you with a cleaner, more cost effective home.