Furnace Filters and Indoor Air Quality
When it comes to choosing the right furnace air filter there are many options available. The efficiency of furnace filters is measured on the MERV scale, or Minimum Efficiency Reporting Values, which rates filter efficiency on a scale of 1-20. On the low end of the cost scale and MERV scale with a rating of 1-3 are disposable fiberglass filters. Made of 1-inch thick fiberglass, these filters are designed to prevent larger particles of dust, lint, and other debris from damaging your furnace.
Filters are tested and rated for for their ability to trap pollen, dust mites, mold spores, dust, pet dander, bacteria and tobacco smoke. Here are how effective the different MERV ratings are at removing various contaminants from the air. Here are
MERV 1-4 : Filters out pollen and dust mites.
MERV 5-8 : Removes mold and dust.
MERV 9-12 : Traps lead dust and most bacteria
MERV 12+ : Filters out all bacteria and tobacco smoke
When choosing an air filter for your HVAC system it may seem like a good idea to buy the filter with the highest MERV rating, since you want to have the cleanest air possible, right? In most cases, you should use a filter in the 5-8 range. The reason is that filters with a high MERV rating will have the smallest pores for air to pass through. This can make it harder for the HVAC system to push air through the filter, reducing system performance. To avoid restricting the air flow, filters with a higher MERV rating should be changed more frequently (at least every three months) to prevent damage to the HVAC system.
Ultimately, if your home's air is dirty enough to require a higher MERV rating, or you're changing air filters more than once a month, you may be better served by having a whole home air filtration system. A furnace air filter is really just designed to keep your HVAC equipment clean to prevent wear and tear. A whole house air filtration system is designed to actually clean the air inside the home.
How Good Is My Furnace Filter For Cleaning the Air In My Home?Disposable pleated furnace filters are probably the most popular option. These filters are made from polyester or cotton paper and remove smaller particles like mold spores and mites, but should be changed frequently to avoid clogging and reducing airflow to the furnace. Pleated filters have a MERV rating of 6 and cost more than fiberglass filters.
The most effective furnace air filters are disposable or permanent electrostatic filters. With a MERV rating of 10 or higher, they offer highly effective filtration and are recommended for homes where allergies or upper respiratory conditions are a concern.
Have questions about furnace filters and indoor air quality? Call MR Plumbing and Electric we're here to help.