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Frequently Asked Questions About Furnace Filters


What is a furnace filter?

A traditional furnace filter is a part fixed to the furnace's induction side in order to trap and retain dust and other airborne particulates, which can cause damage to the blower motor, heating coil and other equipment in the HVAC system. A high efficiency furnace filter is one that improves indoor air quality by capturing smoke, allergens, pollen, pet dander, mold spore and other extremely tiny particles in the air and prevents occurrence of respiratory and allergic problems.

Is a furnace filter washable or should it be replaced?

They are available in both types. Permanent furnace filters are cost effective. However, cleaning such a furnace filter is impractical, as they can never be cleaned thoroughly. Cleaning it is usually an unpleasant task, which discourages maintenance of cleaning schedules thus greatly reducing the efficiency of the filter. After washing, the filter also needs to be dried before refitting to prevent growth of mold. Disposable furnace filters on the other hand can be replaced once they complete the recommended period of use. The cost difference not being huge, disposable furnace filters should find favor on account of better efficiency and ease of installation.

How often do disposable furnace filters need to be replaced?

Replacement of disposable furnace filters depends on a number of factors like the type of filter, the conditions of use recommended by the manufacturer etc. Usually, disposable furnace filters are replaced between one and three months after installation, depending on the mentioned factors.

What can be the consequences if a furnace filter is not replaced?

A furnace filter left in place past its effective replacement time can become clogged by trapped dust and debris thereby restricting airflow, which can lead to furnace damage. It is therefore necessary to ensure timely replacement of the filter.

Is it necessary to buy a furnace filter from the company that manufactured the furnace?

It is not necessary. There are many filter vendors and other sources from where furnace filters compatible to various furnaces manufactured by different companies are available.

How can one ensure buying the correct furnace filter suitable for a particular furnace model?

This can be ascertained by information available through many sources like the documentation supplied with the particular furnace, the furnace manufacturer, and the HVAC contractor who installed the furnace or on the advice of a suitable furnace filter vendor.

How is furnace filter efficiency measured?

Furnace filter efficiency is ascertained by the MERV rating. MERV stands for Minimum Efficiency Reporting Value. The MERV rating is accorded after putting a furnace filter through a strict test devised by ASHRAE i.e. the American Society of Heat, Refrigeration and Air-conditioning Engineers. MERV is a universal value by which a consumer is able to compare air filters. Home furnace filters have MERV ratings from 1 to 12. In plain words a higher MERV value would indicate a more efficient furnace filter than one with a lower rating.