Originally the primary purpose of air filters was to keep system components clean. Clean air to breathe was a fringe benefit. Now more attention is given to cleaning the air we breathe. A dirty filter can have many negative side effects to equipment such as: increased blower power consumption, reduced cooling and heating efficiency, compressor failure, and high cost - shorter equipment life. How often to clean or replace a filter can vary greatly. It can range from one to three months for most homes to every couple of weeks for some buildings. Do not wait for the entire filter surface area to become matted with dust. If most strands of the filter media are coated with dust or debris, it is time to replace or clean it. Some filters clog more quickly than others. Check with one of our filter service contractors before using non standard filters. CAUTION: The same characteristic that make a filter more efficient may require more blower power and could possibly overload your blower motor and reduce air flow through the system. Before purchasing any air filter, particularly "high efficiency" filters, be certain that it is properly sized for your system. Because the "high efficiency filters" may have more resistance to air flow, they may have to be larger in square inches than standard types. Also, it does not matter how efficient your filter is, if the air return duct is not thoroughly sealed against air leaks; unfiltered dirty air will enter the air stream. The dirtier or more restrictive the filter, the more air will come in the return leak. This air is often hot, humid, attic air, which increases the work of the air conditioner, decreases the comfort and increases your cost.