Getting to Know Your Air Conditioning System: Part 5: Air Filters
When air flows through your AC system supply ducts and in to your house, it picks up pollen, dust, and other debris, which get carried back into the HVAC unit. The purpose of an air filter is to intercept all the debris particles and prevent them from getting back into the system and consequently covering and blocking up the blower, cooling coil and ductwork.
This has two main benefits: keeping your AC system clean helps keep it in good working condition and it improves the quality of the air pumped back through the house. Improved air quality can help with seasonal allergies and overall health of everyone in your home.
The higher the efficiency of a filter, the more dust particles will be filtered out. Here is a list of a few filters in order of increasing efficiency:
- Standard panel filters: very cheap and often found in hardware stores; dust spot efficiency less than 5%.
- Electrostatic filters: can be washed and reused but blog up easily; dust spot efficiency ranges from 10-15%.
- Extended-surface filters: offer medium protection to AC equipment and lasts about three months; dust spot efficiency ranges from 20-40%.
- Polyester filters: similar to extended-surface filters but sold in bulk without a filter frame.
- Electronic air filters: very effective but must be custom built; dust spot efficiency of 90% or higher.
- HEPA (high-efficiency particulate arrestor) filter: requires special installation and is most often used in commercial buildings, such as hospitals, that need a clean-room; dust spot efficiency greater than 99%.