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Cleveland HVAC Blog

Use This Guide To Purchase A Furnace Filter

Posted by Paul Wadsworth on Mon, Sep 26, 2011 @ 10:02 AM

With heating season lurking just around the corner, now is the time to perform routine preventive maintenance on your furnace. For many homeowners, that means replacing last year's used and worn furnace filter.

furnace filter guideAs you shop for a new furnace filter, you'll encounter numerous terms that you may not understand. Navigating through MERV ratings, arrestance and pressure drop can be confusing, so here are some buzzwords you should know if you want to select the right filter:



  • MERV: This is an acronym for "Minimum Efficiency Reporting Value," and it essentially expresses how adept the furnace filter is at trapping airborne particles and pollutants. Filters with higher MERV ratings are able to trap smaller particles and eliminate greater quantities of indoor air pollutants.
  • Arrestance: Think of arrestance as being akin to a MERV rating, except that it occurs under test conditions with larger particles. Some lower-quality filters with substandard MERV ratings will attempt to lure consumers with high arrestance scores, but considering arrestance alone is not a good way to choose the best filter.
  • Pressure drop: This metric measures how much a given furnace filter affects airflow within the furnace system. Look for lower pressure drop ratings, as this signals minimal interference and promotes efficient furnace operation.
  • Efficiency: There are two types of furnace filter efficiency--initial and sustained. Initial efficiency tells you how well the filter performs when it is new, and sustained efficiency is an average of how well the filter performs across its expected lifespan.

You may also encounter the term "HEPA" filter. "HEPA" stands for "High Efficiency Particulate Air," and filters that earn this designation perform at higher levels and are held to higher standards than conventional filters. HEPA filters have the highest MERV ratings on the market, between 16 and 20, and they make a good choice if you need a high-performance filter.

Make sure your HVAC system is able to perform to the airflow capacity of any HEPA filter, however, as the material for these filters is dense, and restricts the airflow that most furnaces need.  Generally a HEPA filter requires an added blower installed to help overcome it's higher resistance to airflow.

If you need help selecting the right filter for your furnace or need a heating performance check, don't hesitate to contact the pros here at P.K. Wadsworth Heating & Cooling. We've been providing residents of the Cleveland area with top-notch HVAC service and maintenance for 75 years.

Photo credit:  G&A Sattler

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Topics: merv ratings, hvac preventive maintenance, furnace filters, arrestance, pressure drop

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