In order to select an effective filter, you need to know a little bit about filter efficiency. Furnace filters provide protection for your furnace from pollutants, preventing buildup while cleaning up your indoor air. So when you choose a filter, use these terms to compare efficiency:
- MERV – Most furnaces are assigned a Minimum Efficiency Ratio Value (MERV) rating. These ratings show how effectively a filter will remove microscopic pollutants from the air. Ratings are based on the size of particle that a filter can remove. MERV ratings run from 1-20, but furnace filters are generally in the MERV 1-16 range, as only High Efficiency Particular Air (HEPA) filters are rated above 16.
- Pressure drop – Pressure drop refers to the airflow. When buildup occurs on the filter, the filter’s ability to maintain adequate airflow is compromised. As a result, it decreases the HVAC system’s efficiency. Thus, a low pressure drop rating is desirable. Like particle size, this is an important value to look for.
- Arrestance – During testing, arrestance shows how well the filter will trap dust. But don’t let this number weigh heavily in your decision because real-life situations are much different than those commonly used in testing.
- Dust spot efficiency – Referring to indoor air, this number will evaluate the filter’s capability to remove dust from the air, but only during testing.
- Dust holding capacity – This number is helpful, as it assesses the total dust a filter can trap. Filters are tested at a certain pressure drop so that homeowners can make an equal comparison.
- Efficiency – This rating will evaluate initial efficiency, or how well a filter traps particles, in its new state. It also evaluates sustained efficiency, or how well a filter traps particles throughout its lifespan.
Using this knowledge about efficiency factors, you can confidently select a filter that will protect your furnace and keep indoor air quality at acceptable levels. Contact the experts at Arpi’s Industries Ltd.for help with filter selection, or for any of your heating and cooling needs.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about furnace filter efficiency and other HVAC topics, download our free Home Comfort Resource guide.