AC filters for valley dust and smoke
The air conditioner is also the house's air filter. In a dry valley that sees farm dust all summer and wildfire smoke some years, the filter matters more than most people think.
Dust and your system
Meadows Field averages 5.72 inches of rain a year, and June through September bring almost none of it. Dust collects on the outdoor coil and in the filter all summer. A clogged filter cuts airflow, which can freeze the indoor coil and make the system run longer. Check it monthly in summer.
What a MERV rating means
MERV is a filter efficiency scale from ASHRAE. The higher the number, the smaller the particles a filter traps. The EPA says that if you upgrade, choose at least MERV 13, or as high a rating as your system fan and filter slot can handle, and that you may need an HVAC technician to tell you what your system can take.
That last part matters. A thick, tight filter on a system that can't move air through it can cause the same airflow problems as a dirty filter.
On smoke days
The EPA's wildfire guidance says to set the system to recirculate, or close the outdoor air intake, make sure the filter fits snugly and is in good condition, and consider a MERV 13 or higher filter if the system can take it. Keep doors and windows shut. Replace the filter sooner after a smoky stretch.
Ask at your next visit
- What is the highest MERV filter my system can take?
- Would a wider filter cabinet let me use a better filter without hurting airflow?
- Is outside air coming in anywhere it shouldn't, like leaky return ducts in the attic?
Questions Bakersfield homeowners ask
What MERV filter should I use for wildfire smoke?
The EPA suggests MERV 13 or higher if your system can accommodate it. Ask an HVAC technician what your fan and filter slot can handle.
Should I run my AC when it is smoky?
The EPA says to set it to recirculate or close the outdoor intake, and use a well-fitted, higher efficiency filter if the system can take one.