All HVAC contractors will tell you. The purpose of an HVAC filter is to prevent dust and grease from building up on its fans and other internal surfaces, but consumer concerns over indoor air quality have led many HVAC filter manufacturers to create filters that are also designed to improve indoor air quality. In this article, we’ll discuss the qualities to look for in a quality intake filter.
Whether you are in heating season or air conditioning season, your heating and cooling unit must have adequate airflow to function properly. Intake filters have the challenging task of filtering air intake without restricting air flow.
If the filtration is too fine, your HVAC unit will be starved for air which could result in damage to the HVAC system and increased energy bills. This is the reason that many HVAC contractors and service technicians discourage the use of HEPA filters on air intake vents.
A coarse filter, like a bargain priced cardboard blue or green fiberglass filter, allows too much dust to pass through it. Many technicians notice system problems in units with this type of filter use similar to those that occur in systems where no filter was used.
Researchers have found that the best solution to the airflow problem is a pleated paper filter. Pleats increase filtration surface for a given filter size. They also allow for maximum air flow through them.
Dirty intake filters imped airflow and should be changed at least once per month. Pet owners should change filters more often. Failing to change the filter regularly is a common cause of HVAC failure.
There are two methods filters use to remove dust from the air: electrostatic attraction and screen size.
As dust is carried through moving air, it becomes charged. The charged particles are attracted to other charged particles. This is the same effect you see at work on dust covered ceiling fans and intake vent covers. Fiberglass and polyester fibers easily attract charged particles.
In the same way a sieve allows water to pass but retains your pasta, HEPA and paper filters trap dust and other allergens by creating holes in the filter that are smaller than the size of the undesirable particle.
The best intake filter for your unit is one that captures dust efficiently without restricting airflow to your system. While you may like the idea of a HEPA filter for your system, they tend to restrict air flow too much.
At about a dollar each, flat fiberglass or polyester filters are the least expensive, and also the least effective.
The best filter should be pleated paper or a paper and polyester combination. Ultimately, the best filter is the one that is regularly changed.