If it's not yet broken, do you need to fix it? We have heard variations of this questions for years, and much like exercise keeps the body fit, preventative maintenance helps keep your furnace and AC fit! One item that tends to get neglected and can make ALL the difference, is the filter! We recommend that people use their smartphones to remind them to change their furnace/AC filter in a timely manner because not changing the filter will result in an untimely death of your furnace/AC...and they are NOT inexpensive to replace! Add to this the energy dollar savings of having properly changed filters and the money you will save on maintenance costs, you will see that the cost of a filter is a bargain, to say the least!
Usage is a key factor in how often you change your filter. If you use your furnace a LOT, you will need to change your filter more often, and similarly, if you don't, less often may work. You may hear folks that say "every 30 days your filter should be changed" with the less expensive fiberglass filters, or "6 months or more" for the higher end, better filtration offered by the pleated filters; the fact is this though, if you change it more often, you will help your system breathe better and this will help keep your furnace operating at its highest efficiency.
So, how often should YOU be changing your furnace's filter? The answer is, "it depends." Figuring it out is easy, though, and we aim to do just that with this article!
The goal for your filter is to be able to "filter", which means that air needs to be able to pass through. If your filter is overly dirty, and air cannot pass through, then it isn't doing its job, and the dirt that isn't filtering is staying in your system! This results in poorer air quality and LOTS of dust! Have pets? Pet hair is a key "clogger" and may mean that your filter gets dirtier, quicker. Waiting a month to change your filter simply because that is the "recommended amount of time", may not work for your home. If you have a 6-month filter, you may need to change it every 3-4 months. You will need to pay attention to your particular situation and change it according to the dirt you are seeing, rather than just by the recommendations on the package.
Do take note though: a dirty filter is a good thing too...as long as you change it appropriately. Why, you ask? It means your filter is doing its job! If your filter is always clean, that means that the dirt is STILL there; it just isn't getting filtered, and that could be a MAJOR problem!
So bottom line, when do you need to change your air filter? Well, a properly working filter will look like a piece of furniture...it may have a fine layer of dirt/particulates on the surface, but not deep in the filter. If you see crud through the filter itself, it is probably time to change it!
When in doubt though, it is ALWAYS better to err on the side of caution. Filters are inexpensive (especially in relation to replacing a furnace or repair), and you should change them VERY regularly. We have never had someone tell us they regret changing their filter, however, we have had MANY tell us they wish they would have changed it sooner!