Home technology expert Ross Trethewey shows how air filtration systems work and how to build a localized DIY air filter.
What is a MERV Air Filtration System?
MERV stands for Minimal Efficiency Reporting Value, a value that measures how effectively a filter stops particulates of varying sizes from passing through and into the air system.
The higher the rating, the more effective the filter is at capturing smaller particles. Ratings 1-16 are HVAC use; in general, houses usually have around a MERV 5-12 system. MERV 17-20 are HEPA filters that are used in hospitals and laboratories.
Can I Install a MERV 16 or HEPA Filter Myself?
Homeowners cannot just install a MERV 16 or HEPA filter into their homes. In many circumstances, the HVAC systems homeowners have in place simply aren’t strong enough to handle higher-rated filters, as the more filtration the air has to go through, the more resistance it has to overcome.
Even if you were to get a thicker filter that increases surface area, meaning less resistance, you’ll have to check if your HVAC system has enough space to install a thicker filter. Check with an HVAC technician to check what rating your system can handle.
Steps for Building a DIY Air Filter:
If you are unable to acquire a higher rated filter, Ross demonstrates how to build your own DIY air filter. By taking four MERV-13 air filters and duct taping them on all four sides of a box fan, you’ll have a localized air filter for any room you want.
For about $150, you can have some peace of mind during wildfires and other disasters that impact our air quality.
- Cut out a piece of cardboard that’s the same size as the box fan to use for the back.
- Place the cardboard on a table and take the four air filters and stack them on the edges of the cutout, with the airflow arrow pointing in (air intake side).
- Take duct tape and secure each filter to the fan.
- Duct tape the cardboard backing.
- Place the fan on the other side and secure it with duct tape.
- Remember that you’ll have to replace the filters every once in a while. For Ross’s DIY system, the filters should be replaced about every six months.
Ross built the air filter using four, 20x20x2, MERV-13 air filters, which Ross got from Filterbuy. He duct-taped the filters to a cardboard box and a 20-in 3-Speed Box Fan, which is manufactured by Lasko, though any 20″ fan would work for this application.
Expert assistance with this segment was provided by Neil Comparetto.