by Susan Nichol

Most people know that changing the filter in your furnace is important, but it often gets missed as a part of regular maintenance or they don’t realize the strain you place on your furnace when you don’t simply change the filter.

A clean filter offers some great benefits aside from extending the life of the furnace, such as cleaning the air you breathe, prevention or control of allergens (dust mites, pet dander and molds) and my personal favorite – less dusting (yes, you can dust less often with a clean furnace filter).

Filter changes should be a regular part of the maintenance of your furnace but it certainly should not be the only item to maintain the efficient operation of your furnace.  Annual or semi-annual (when you have both heating and cooling) preventative maintenance by a professional is the best way to keep your furnace running at its peak performance.

What happens when you don’t change the filter? 

The filter’s primary purpose is to remove dust and other particles from the air before it passes though the equipment and if air conditioning is present, the cooling coil too.  A clogged filter can make the furnace work harder to move the air because the filter is full of debris.  With a dirty filter – dirty air enters into your furnace and it damages the internal working of the furnace.

Dust and debris can attach to the fan blades making it harder to move air and a dirty fan motor makes the furnace work harder and shortens its life.  The cooling coil on the furnace can get clogged when the filter is not changed regularly, see picture. When this happens there is limited airflow as well as mold and debris entering the air you breathe.  You should know that an older cooling coil can over time get clogged even if the filter is changed regularly, but clean filtration will help it last longer.

Picture: This is a dirty cooling coil, the customer wondered why they did not have airflow, they thought a duct was disconnected. Note: The darker part of the coil is where the dust and debris was removed.

Dirty Evap Coil 002-resized-600

A clogged filter can also trip a safety on your furnace making your furnace inoperable; because the clogged filter chocked the air flow.

Failure to change the filter can be expensive in time off work, the furnace not being operational, diagnostic bills, repair bills, premature equipment replacement, etc.

Although you may not have the time to change the filter or know how to do it, call us (408.374.7292) for a complete preventative maintenance appointment and we can get your furnace tuned up and ready for winter and we can also do a safety check on it.


If you need help with temperature, contact Cold Craft, Inc.

408.374.7292 or [email protected]

By Published On: September 22, 2014

Share This Article!


Subscribe to our newsletter and stay updated on the latest.