Red Flags: How to Spot Unhealthy HVAC in Homes

Every week, the detail-oriented folks at Green Scene Home Inspections will give CandysDirt.com readers an education in inspection. Want to see what they see? Tune in  for “Upon Closer Inspection.”

One of the most common problems we run across as home inspectors is improperly maintained HVAC systems. And the No. 1 issue with HVAC systems is people neglecting their air filtration systems. 

It’s important to change the filters on your vents regularly — most need to be changed once a month. You should also clean the vents themselves, at least quarterly. Dirty, clogged vents make your HVAC work harder to heat and cool your home, not to mention recycling dirty air through your home.

Above you’ll see a good illustration of the quality of the air coming out of a dirty vent. That’s not a shadow.

You’ve probably noticed condensation on or around your vents, particularly when it’s humid or when we have dramatic weather shifts. In a functioning system, the condensate line carries the water away. In an improperly maintained system, moisture can collect and grow mold. And this right here is black mold. 

A clean filter of the wrong size is better than nothing, but not by a lot. It’s a good idea to check the size before you buy. And if you get the wrong size, don’t just shove it in there. #lazy

If you have pets, you may need to change your filters more often. The best practice is to check your filters at least once a month, and while you’re changing them, clean the inside of the vent covers as well.

Another good rule for better indoor air is to clean your registers (intake and output vents in each room of your house) every three months. A clean HVAC system lasts longer and improves the quality of the air in your home.