Before most of us buy our first home, we usually live in an apartment complex. While living in an apartment or condominium unit, we rely on a superintendent to think about the furnace, the water heater, and all the other systems that make your building run.  After moving into our first home, we find ourselves in need of a heating and cooling system and the variants that run the equipment.

One of the first terms people encounter in the HVAC world is the MERV rating.  In the process, we run into what is called a MERV filter.  Here are the Cliff Notes on MERV ratings and what they mean.

The term MERV stands for the Minimum Efficiency Reporting Value.  The Minimum Efficiency Reporting Value measures the performance of air purifiers, specifically large purifiers intended to clean an entire house or building.

In other words, how effective is your air filter?  MERV ratings range from 1-16. The higher the MERV rating on a filter, the fewer dust particles and other contaminants can pass through it. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) designed the MERV scale to represent a filter’s worst possible performance at removing particles .3 to 10 microns in size (that’s really small!).

Some of the common particles that filters are tested for include pollen, dust mites, textile and carpet fibers, mold spores, dust, pet dander, bacteria and tobacco smoke. Most residential systems can adequately remove airborne contaminants with a filter rated MERV 7-12. MERV 13-16 is typically found in hospital and general surgery settings.

Higher Is Not Better

It is worth noting that the higher MERV rating are not necessarily automatically better.  The higher the MERV rating, the smaller the pores are for air to flow through an HVAC filter, creating more resistance in airflow than a system is designed to manage, making it inefficient. Reducing the air flow in your system can worsen the air quality in your home, putting damaging pressure on the fan of your furnace or AC system.

Filters with higher MERV ratings need to be changed more frequently (at least every three months) to avoid restricted airflow that can cause your system to work inefficiently or possibly even damage it.

So it is worth doing some research. Find out what the highest MERV rated filter needed that will still allow for maximum airflow in your system.

Breathe easier, figure out the Merv Rating on your HVAC equipment.  

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