Q & A.
A: You should only change your filter when it's dirty. How long it takes to get dirty will be different for each and every system, as there are many things that affect this timing.
I've heard more than one homeowner say that it seems like their filter takes forever to get dirty. While this may seem like a good thing (less money spent on filter replacement), it also means that the filter you do have is not doing anything to help you clean the air within your home. A common Cause of the "forever-clean filter syndrome" is that the filter is either being. bypassed or the air handier is pulling its air from somewhere other than the return grille.
If the air handier is not pulling in air through the return grille and filter, where is it coming from? The space where the ducts are located. So, if you have a return grille in the floor of your home, the return air is being sucked into your house from the basement, crawlspace, or attic. So, if you have a forever-clean filter then you need to seal the ductwork, plain and simple.
There are a few main types of filters; fiberglass filters, pleated media filters, and electrostatic filters. The one-inch see-through fiberglass filters are designed to keep rocks and sticks out of the ductwork--mainly to protect the system itself, not your lungs.
The pleated media filters are non see-through filters that have a zigzag pattern, which allows more surface area of filter to be squeezed into a smaller package. These filters do a great job of trapping the majority of dust, dirt, and animal hair typically found in a house. The dirtier they get, the more efficient they become at filtering the air. Be warned! This "clogging" of the filter also restricts the flow of air, which can have a negative effect on the performance of the system and decrease the life of the machinery itself. Check the filter on a normal basis initially to see how long it takes to get dirty. Then, set your maintenance schedule based on this timing.
The third type of filter is the electrostatic filter, which is efficient when clean but less efficient as it becomes dirty. This type of filter requires relentless maintenance. If you want to play it safe, go with a media filter.
Before running out to buy a better filter for your home, please understand that this simple act of wanting cleaner air could produce some negative side-effects. When your HVAC system's ductwork was designed and installed, it was likely sized around the restriction of a one-inch fiberglass filter. If you replace this filter with a better one, it will change the way the system performs. It may reduce the amount of air that is able to flow through the air handier, it may cause the motor on your HVAC system to burn out earlier than it otherwise would, and it may cause the HVAC system to suck more air in through the holes in the ductwork that it used to. So, make sure your ductwork is sized properly to accommodate for a better filter before making any changes. Talk to your HVAC contractor or building performance contractor.
If your concern is air quality, the most significant action you can take is to seal the ductwork itself. By eliminating this leakage, air quality should improve drastically. But again, changing the way air moves through the ductwork will affect other aspects of the system as well. So, be prepared to do your homework before starting, or hire a professional.
Isaac Savage is president of Home Energy Partners, a Building Performance Contracting firm that is located in Asheville, NC. He can be reached at 828-350-1155 or on the web at www.HomeEnergyPartners.com.
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|Title Annotation:||DEPT.: the healthy home|
|Publication:||New Life Journal|
|Date:||Feb 1, 2006|
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