Just How Efficiently Can A Furnace Filter Function?

• MERV: This is the best method for rating the filtration quality of any furnace filter. MERV, or Minimum Efficiency Reporting Value, rates a filter's ability to trap particles. Most particles are so small that the human eye cannot see them, and they are measured via microns.
• Pressure Drop: This rating shows how well a filter maintains airflow. When a filter is dirty (or full), the pressure drop increases and the furnace's efficiency decreases. When a filter is clean, the pressure drop decreases and the furnace's efficiency increases. Therefore, you'll want to select a filter with the lowest pressure drop rating possible.
• Dust Holding Capacity: This metric reveals the filter's capacity to hold dust within a particular pressure drop. Don't compare filters with different dust holding capacity pressure drops, as you'll be comparing their efficiency at different airflow levels.
• Initial and Sustained Efficiency: A filter is rated in its "initial" state to show how well it works before used; then, a filter's sustained rating shows its efficiency over its lifetime of use (generally a month or two).

How will understanding these ratings help you select a filter? It's all about airflow and particles:

Choosing a filter that is very dense means it can trap the tiniest particles, but it will restrict airflow. Your equipment needs to "breathe." If it doesn't, you are (a) overworking your furnace, (b) reducing your equipment's efficiency and, (c) not cleaning the air effectively. Therefore, a furnace filter has to walk a fine line between density and airflow, and you can use these ratings (and your system's manufacturer's guide) to select the right furnace filter.

If you need help with finding the proper filter for your equipment, contact Rodenhiser. It's our business to know how your home comfort equipment should operate for maximum efficiency.

Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about furnace filters and other HVAC topics, download our free Home Comfort Solutions Guide.

Rodenhiser Plumbing, Heating and Air Conditioning serves the Route 495/128 area of Massachusetts. Visit our website to see our special offers to get started today!