Do I have a story to tell you -- another one of those lessons I've learned the hard way so you won't have to.

While working on a recent column -- "What are Those Grimy Black Lines Around the Edges of My Carpet?" -- I asked my husband whether he'd recently replaced the filter in our heating, ventilation and air conditioning system, or HVAC system. I got one of those blank stares that easily translated as "Nope. Didn't even think about it."

When we bought this house in Jan. 2014, we had the HVAC system inspected and serviced. Then we totally forgot about the filter. We assume it was replaced at that time. But at this point, we're talking more than two and a half years! Opening the filter door was the scariest thing ever. It was nearly black and covered in what looked like fur -- so gross. I can't imagine why the entire system didn't just blow up out of sheer rebellion for lack of attention.

The problems

HIGH ENERGY BILLS. When the heat, ventilation or air conditioning is running, 100 percent of the air in your home passes through a filter, typically twice every hour. When the filter is clean, the air passes through easily. When the filter gets clogged up with all the stuff it's filtering out, the system has to work much harder to keep the air moving. The dirtier the filter, the less efficient the system can be. According to the Department of Energy regular filter changes can cut 5 to 10 percent off your energy bill.

FAMILY HEALTH. A quality filter captures the harmful bacteria typically found in sneezes, coughs, viruses and molds, as well as pollutants like dust and car fumes. If you have allergies or asthma, indoor air pollution can trigger your symptoms. Most people don't realize that indoor air pollution levels are actually much higher than outdoor levels -- two to five times higher, according to Dr. Julie McNairn, allergist and immunologist in private practice in Middletown, Ohio. When particles become airborne, you can breathe them in and experience an allergic reaction. The HVAC system can harbor and spread mold and other allergens.

GRIMY CARPET STAINS. It's called filtration soiling, and it shows up as dark, shadowy lines on the carpet, along the baseboards, under the doors, beneath the draperies, and along the edges and crevices of carpeted stairs. Filtration soil is as ugly as it is gross. It comes from airborne pollutants passing through the carpet as the air is drawn through the crack between the carpet and the baseboard, around the drapes or under closed doors. It's an accumulation of soot from dirty ducts; smoke from candles and the fireplace; tobacco; kitchen grease from the oven and cooktop; smog, auto emissions; and outdoor pollutants. All of that stuff gets trapped in the air filter! Once the filter is full, the system will send the pollutants back into the house through the ducts, where all of that icky mess gets lodged into corners and crevices.

The solution

CHANGE THE FILTER(S) OFTEN. Check your filter every month, especially during months of heavy use (winter and summer). Keep in mind that some systems have multiple filters. Take some time to research your system to know exactly what you have. If the filter(s) look(s) dirty after a month, change them. Homes with pets and multiple occupants, or homes located in regions with general air pollution may require more frequent changes. Change the filters every three months at minimum. A dirty filter will slow down airflow and make the system work harder to keep you warm or cool, thus wasting energy. A clean filter will also prevent dust and dirt from building up in the system, which could lead to expensive maintenance and/or early system failure.

CALCULATE. Mark your calendar so you check your filter every month and replace it as necessary.

AUTOMATE. My filthy filter wake-up call prompted me to do some research, which is how I found FilterEasy, and online company that delivers our exact HVAC filter when it's time to change it, at a cost that is cheaper than the very same filter at the store. We've received our first shipment, and its arrival was unforgettable. I set up an account online, identified the exact filter we need (they're listed by size, including custom sizes). I am happy to let you know that the nice people at FilterEasy are offering you EC readers a first set of filters for free (except for shipping). Go to Of course, you can cancel anytime.

Mary invites questions, comments and tips at, or c/o Everyday Cheapskate, 12340 Seal Beach Blvd., Suite B-416, Seal Beach, CA 90740.


The World's Latest E-Edition

Connect With Us


Load comments