Keeping a furnace filter clean during the winter months is challenging. Some models have a removable type, while others have a disposable one. For maximum furnace efficiency, the filter should be changed or cleaned regularly. The owner's manual will have a specific guideline on how often this should be done and what type of filter it is. For those uncomfortable replacing or cleaning the filter, have a furnace repair technician do it as needed.
For people with allergies, the type of filter used is critical. High Energy Particulate Air (HEPA) filters contain multiple layers for maximum defense against dust and dirt. HEPA types are designed to purify the air by reducing the number of particles that pass through the field. There is a rating system called the Minimum Efficiency Reporting Values (MERV) for the amount of filtering. The higher the number, the more stringent the filter.
These come in a variety of models. Replaceable HEPA filters come in the scented form to improve odors. For allergy sufferers, this may be more harmful than helpful. In homes where smoke or dampness permeates the area, scented ones can improve the smell. Some do not fit the older types of furnaces. In order to make them compatible, a separate device may need to be installed.
When HEPA filters are not an option, high-efficiency types may be used instead. These are pleated and contain an electric charge to increase the number of particles attracted to the filter. There is usually a layer of fiberglass over the pleated cardboard or Tyvek interior to trap extra particles. As the filter becomes full, airflow is reduced. This reduces the efficiency of the furnace, making it harder to send out warm air. Changing this filter regularly has a large impact on air cleanliness and energy efficiency.
Pleated filters are the same as high-efficiency ones without the electrical charge. Standard models are most commonly made of mesh from natural fibers or fiberglass. The density is not as intense as those of the allergy-specialized HEPAs.
Some furnace filters are not disposable. Made from heavier materials, such as foam or natural fibers, these filters should be removed and cleaned every few months. They are not as stringent as HEPA filters. Their purpose is to be a basic gatekeeper for dust and dirt, not a high-efficiency device. These may be more daunting to remove and clean. They often have a metal frame that screws in or attaches behind other parts. It is best to ask an HVAC professional to clean it or to learn how. The instructions can be found in the furnace owner's manual.
Most frames need to be removed from the appliance before taking out the filter. The filter is then hosed off or run beneath a stream of water into a sink until the water runs clear. The filter should be wrung out, then returned to its proper place.
After several years of use, these filters need to be replaced. Even with proper maintenance, they may not be completely clean of impurities. When they begin disintegrating, it is time to purchase and install a new one.