furnace filters

The Ultimate Guide to Understanding Furnace Filters

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There are many brands and types of furnace filters on the market, with differences in price and stated benefits. Find how the right furnace filter saves you energy and extends HVAC life. Our ultimate guide to understanding furnace filters tells all.

What’s the Purpose of a Furnace Filter?

The main purpose of your furnace air filter is to remove airborne particles such as dust and dirt so that furnace equipment keeps as clean as practical. Without the right filter, grime can buildup on furnace parts, causing deterioration and a need for eventual repair work. Problems like these can significantly reduce the lifespan of your expensive HVAC assets.

Through trapping not just dust but micro-organisms such as pollen, mold, bacteria, and other irritants, furnace filters also improve the air quality in the home. All this makes keeping on top of furnace maintenance well worthwhile.

Guide to Furnace Filter Replacement

Regularly inspecting, cleaning, or replacing the air filter is essential to keeping your furnace in tip-top condition. As a guide, furnace filters should be replaced every three months. However,  this varies depending on how heavily the furnace is in use and the type of filter in place.

Signs that your HVAC is not running at peak efficiency are — the home taking longer to reach desired heat levels or poorer air quality. Checking the furnace filter should be your first step.

Inspecting the Filter

Generally, the filter is found inside the blower compartment by the intake vents/return duct. If you’re unsure, a quick check of the manufacturer’s user guide should set you straight. If the filter surface has turned gray with buildup, it’s time for a change.

Understanding Furnace Filter Types

There are several different types of furnace filters on the market, including:

    • Charcoal
      These are good for allergy sufferers as they capture more pollutants than standard filters.
    • Fiberglass
      These are the most commonly used filters for home furnaces. They are disposable and cheaper than most other filters.
    • HEPA
      These are high-efficiency filters that can remove up to 99.97% of airborne particles. They are available in paper, fiberglass, or mesh material models.
    • Pleated Allergy
      These are made from paper fiber that is pleated to increase available surface area. The increased surface area assists in capturing higher levels of airborne particles.
    • Washable
      These are textile-based and can be hand-washed, enabling reuse over and over for up to a year. It’s generally recommended that these filters be washed every month. They are more expensive than other filters due to their longer life.

Filter Sizes and Thickness

Another aspect of fully understanding furnace filters includes identifying the exact filter size and thickness required in your HVAC system.

Filter size:

While many brands of filters are interchangeable, the furnace filter must still be a precise size. Slightly under or over the recommended size, and a snug fit won’t be achieved. In this case, there will be air flowing around instead of entirely through the filter. Consequently, contaminants will get through, with grime building up and all the attendant problems that dirty filters can create.

The filter size should be specified on the furnace filter cabinet or check the manufacturer’s specifications.

Filter thickness:

Filters range in thickness from one inch to five inches. The thicker the filter, the more efficient and long-lasting it will be. However, never be tempted to buy thinner filters and fit multiple filters into the cabinet. The airflow will become too restricted, impacting negatively on HVAC operation.

Filter Efficiency Ratings

All air filters have an assigned Efficiency Rating level. The EPA provides a quick guide on furnace filters efficiency ratings. The MERV (Minimum Efficiency Reporting Values) system rates filters from Level 1 through to 16. The higher the level, the better the filter works at removing airborne contaminants.

Households with members suffering from severe allergies may find that opting for filters with a high MERV will provide optimum air quality and help relieve their symptoms.

Benefits of Having the Right Furnace Filters

Armed with a better understanding of furnace filters, you can now see the benefits of having clean, efficient, snug-fitting air filters in place. Removing airborne contaminants:

  • Heads off repairs
  • Protects the life of your HVAC equipment
  • Minimizes the energy required to power your HVAC, thus reducing energy costs, and
  • Improves overall air quality for the household.

At Briggs Heating and Cooling, we can help you achieve these benefits with an affordable maintenance plan. If you’re in Northern Virginia, we’ll schedule twice-yearly service calls that include inspecting, cleaning, and repairing your HVAC, including the furnace filters.