Serving Gillete, NJ & Neighboring Communities

How to Choose the Right Furnace Filter

When it comes to your family’s indoor comfort, nothing’s easier to do than cleaning or replacing your furnace air filter. Sure, it’s not the most exciting thing on your to-do list but important, nonetheless.

Yet there’s more to filters than meets the eye. Originally designed to protect the moving parts of the furnace, today’s filters prevent harmful airborne particles from cycling back into your living spaces. They are available in a variety of materials, sizes, and for different applications. Before simply replacing your filter with the same exact make and model, here are a few things to consider.

MERV Rating

Every furnace filter is assigned a MERV rating, or a “minimum efficiency reporting value,” ranging from 1 (lowest efficiency) to 20 (highest efficiency). The higher the rating, the more effective the filter is at attracting and trapping airborne particles. Most residential filters range from a 6 to 12 MERV while higher rated ones are mainly used in commercial and hospital settings. The rating refers to a filter’s density. Denser filters are capable of trapping more and smaller particles but will require more frequent changing to prevent clogging. Check your furnace manual for the MERV rating best suited for the unit.

Thickness & Size

Filters come in a variety of sizes although the most common are 16” x 20”, 20” x 25”, and 16” x 25”. Thickness varies, too, from one to five inches – the thicker the filter, the more particles it can trap. A thicker filter will also require more frequent changes to prevent it from clogging the furnace.

Disposable vs. Washable

Replacing your furnace filter regularly helps keep particles from damaging critical furnace components like the fan and heating coils. Disposable filters are just that – made to be tossed after one use. They also tend to be lighter and less expensive than models that can be cleaned. Washable filters have a heavier aluminum frame and electrostatic fibers that attract and trap particles. They can last a few years but do need to be washed regularly. You may find this tedious since washing typically involves separating the filter into layers, washing them separately, and making sure each is completely dry before reinstalling it to prevent mildew and mold growth.


Climate also plays a roll in what furnace filter suits your home best. For example, mold is a concern in humid, rainy areas so you’ll want to select a filter with a MERV rating of at least 6 to block mold spores from entering the furnace and recirculating inside your living space. Homes in drier regions can get by with a lower MERV-rated filter, though it won’t do a great job of keeping larger particles out.  

Contact C&D Cooling & Heating if you’re unsure of what type of filter might best suit your furnace. Better yet, contact us to perform our furnace tune-up service which includes checking filter and, where appropriate, advising you not just that it needs to be replaced, but what size and type to purchase.