Why Use a Furnace Air Filter?

Using a furnace air filter is really a must–if you’ve ever seen the amount of dust and debris that a filter can collect over the course of a couple months, you’ll realize that you don’t want that stuff floating around your home unchecked! (The EPA considers indoor air quality to be a major issue–and one of the first steps in improving it is by preventing duct contamination.) But there are several furnace air filter types that you can choose from, and it can be overwhelming if you just show up at Home Depot one day and see the rows and rows of options. We break them down here into several types so that you can make an informed purchase.

One of the most important things to understand when choosing a furnace air filter is the MERV (minimum efficiency reporting value) rating system. Ratings go from 1 (lowest) to 20 (highest) and take into account three factors: ability to remove particles, ability to resist overflow, and the air filter’s expected lifespan.

furnace air filterFlat-Paneled Fiberglass Filters

The biggest thing these filters have going for them is that they are inexpensive. So if you know yourself and that you won’t be willing to shell out $10-15 every few months to replace a higher-grade filter, then this type of furnace air filter is certainly better than nothing in terms of protecting your equipment (then again, make sure you are taking all costs into account, because these filters do need to be replaced once a month). Most of these have MERV ratings between 1 and 4, so they don’t catch the microscopic particles that higher-rated filters can.

Pleated Polyester Filters

Pleated filters can collect a great deal more dust and small particles than flat-paneled filters can (the pleats drastically increase the surface area of the filter–think back to your days of science classes!). Pleated air filters usually have a MERV rating between 7 and 13, though high-efficiency versions can go up to 16. These filters should be replaced every three months.

HEPA Filters

Though pleated filters at the higher range can achieve similar MERV ratings, HEPA (high-efficiency particulate air) filters are generally considered the gold standard for air filtration. The downside is that they usually require retrofitting your HVAC system, since they are both too large to fit in the standard filter box and can actually restrict airflow in a standard HVAC system. If you have severe allergies or asthma, though, it may be worth looking into a HEPA filter.

One last option for a furnace air filter is an electrostatic filter–these filters are washable, so they don’t need to be regularly replaced like the three options above. Stay tuned next week for more info on electrostatic filters! In the meantime, if you have any questions, feel free to contact Dan at 720.876.7166 or dan@sensibleheat.net.