I had a customer ask me a question the other day – “Can I just vacuum the dirt off my furnace filter instead of replacing it?” This is actually a great question, so I wanted to take some time to explain what happens when your furnace filter starts to fill with dirt, and why you need to change it regularly.
The short answer to the customer is “No, you can’t just vacuum the dirt off the surface of the filter.” That’s not a really satisfying answer, though. What you need to understand is how filters work and what happens if you don’t change them regularly.
A New Filter
A new furnace or HVAC filter has multiple layers of tightly knit filtering media that are electrostatically charged, which attract microscopic particulates in the air, capturing them and removing them from the air. Larger particulates, like dirt, dust, and pet dander, get caught on the surface of the filter. Over time, as more particulates are captured, the filter becomes even more efficient, capturing more and more dirt and dust as the air blows through.
The Tipping Point
As the filter captures more and more dust, dirt, and smaller particulates in the air, the filter media gets full. Smaller particulates are captured by the fibers in the media, and other particulates build on these. Eventually, the filter is full, and while it will still capture dust and dirt being forced against it, air has a harder time getting through. This means that your furnace or HVAC is working harder to pull air through and blow through your house. This is damaging to your HVAC unit, and requires more energy, resulting in increased energy costs.
Can I Clean the Filter?
Vacuuming the surface dust and dirt off the filter doesn’t really get it clean. The surface dirt isn’t what’s clogging the filter – it’s the microscopic particulates inside the filter media. These particulates are electrostatically bound to the fibers, so removing them won’t be easy. And if you have just a regular, disposable HVAC filter, the stress of the increased suction can warp the filter, allowing unfiltered air through around the frame.
Vacuuming a disposable furnace filter will wear the fabric of the media, resulting in holes or tears in the material, allowing already captured dust and dirt to get through, as well as unfiltered air blowing into your HVAC system.
Costs and Benefits
Ultimately, the increased cost of trying to reuse a dirty filter isn’t worth the savings. You’ll spend more on increased energy costs, additional wear and tear on your system, and poor quality air flow and dirty air blowing through your home.