HVAC filters are a device used to clean the air, in HVAC (Heating, Ventilation, & Air Conditioning) systems. These filters remove impurities and contaminants such as human skin particles, pet dander, pollen, fabric particles, germs and bacteria that are often found in residential, industrial and commercial spaces.
HVAC systems are used in almost all buildings and work by drawing in air through ductwork, heating or cooling it, and then releasing it into the building. Thus, these systems are integral to maintaining indoor air quality. Filters used in heating, ventilation and air conditioning systems help clean the air before it enters circulation.
While filtration can improve human and animal health by removing potentially harmful germs and allergens, it is also important for protecting ventilation equipment to improve efficiency and longevity. HVAC filters prevent particles from clogging the machine.
Failure to use or regular cleaning of air cleaner filters can lead to equipment failure due to obstructed airflow. Improperly maintained HVAC filters lead to increased energy and repair costs.
To avoid these additional costs and possible damage, many ventilation systems come with a series of filters rather than a single filter. Although filters are required at the air intake point to eliminate build-up in fans and ducts, some heaters and air conditioners have secondary filters at the air outlet to further improve air quality.
Types of HVAC filters, varying in style, size and materials, offer varying degrees of filtration, resulting in different levels of air quality.
Although filters can be found in virtually every HVAC system found in virtually every modern building, some industries, including the medical, biopharmaceutical and food processing industries, use specialised filters – HEPA air filters and ULPA filters, which are extremely effective at removing even microscopic particles.
Some heaters and air conditioners have secondary filters on the air outlet to further improve air quality.
HEPA and ULPA filters are often very expensive and require frequent cleaning or replacement. Although these types are used in heating, ventilation and air conditioning systems, more common filters used in ventilation include fibreglass filters, polyester pads and electrostatic filters.
A filter pad, which is a physical barrier that allows air but only a limited amount of particulate matter to pass through, varies in design for each type.
Fiberglass is the most common and economical type of HVAC filter available. The panel is made of glass fibre fibres that form a web-like structure. Glass fibre is often reinforced with metal mesh before installation on a solid cardboard frame.
Polyester filter pads are designed in a similar way, but a combination of fibres such as ceramic, carbon, glass fibre and cotton can be spun with polyester to increase strength and reduce porosity, allowing fewer particles to pass through.
Frames vary in construction from dense cardboard to metals such as aluminium. Electrostatic filters, unlike fibreglass and polyester filters, do not simply block particles. In these filters, the panel has an electrostatic charge that, in addition to blocking, attracts dust and debris.
While some come pre-charged, the airflow over these polypropylene fibres is often sufficient to generate the static charge required for enhanced filtration. These filters can also be housed in cardboard or galvanised frames.