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The Wrong High-Efficiency Air Filter Might Spell Disaster for Your HVAC System!

pleated-air-filterAlmost any modern home can benefit from air cleaners of some type. Indoor air quality is often poor because homes are built today to seal out the heat in summer and seal it in during winter—and that means not much fresh air circulation.

What type of air cleaner is best for a home? There are plenty of options, and our IAQ experts at Purls Sheet Metal and Air Conditioning are happy to help you find the best. In most cases, improving air quality starts with putting in filters and then finding what other devices might help. Filters are almost always a good idea…

…except when the wrong type of filter goes in. When it comes to high-efficiency filters, such as the HEPA filter, you can have too much of a good thing. Too strong a filter can damage your HVAC system.

Filter Efficiency, MERV, And Airflow

You probably have a good idea how a filter works: it’s a mechanical device made of a weave of fibers that prevents larger pollutants from passing through it. Filters come in a wide range of strengths, from the “rock catcher” panel filters you find on simple window air conditioning units to the powerful filters installed in industrial clean rooms.

The measure of the efficiency of a filter is expressed as minimum efficiency reporting value, or MERV. The higher the MERV number, the more effective the filter is at trapping small particles. For example, the window unit AC we mentioned before would have MERV 2. A filter with MERV 11 is effective at trapping pollutants down to .3 microns in size, which takes care of most household particles, but wouldn’t be effective against chemicals, smoke, and organic pollutants. Above MERV 16 filters are extremely powerful, able to stop many pollutants smaller than .1 microns.

However—and this is important—getting a filter for your home isn’t as basic as getting the most powerful filter you can afford. The tighter the weave on the filter to increase its MERV rating, the more resistance the filter places against airflow. The blower fan in your HVAC system may not be able to handle anything stronger than MERV 12. A filter that blocks airflow will raise the air pressure in the HVAC ventilation system, which can damage ducts and even the AC and heater. It will also mean lower comfort around the house, since there will be reduced airflow coming from the room vents.

Finding the Right Filter

You probably won’t need a HEPA filter or anything stronger than MERV 16 in your home, and the HVAC system may be suited to something less powerful. To ensure you have a filter that 1) does the filtration job you need, and 2) won’t harm the HVAC system or lower comfort, only work with IAQ a professional HVAC contractor in Fresno, CA. If you can’t get a filter strong enough to remove all the pollutants affecting your home, the IAQ experts will find an electronic air purifier to pair with the filter that will take care of the particles that escape.

Enjoy great indoor air quality with our help! Purl’s Sheet Metal & Air Conditioning: Quality Is the Cornerstone of Our Success Since 1952.

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