Quarterly
HVAC filter swap
The filter on your furnace or air handler is the single highest-leverage maintenance task in your house. A clogged one makes the blower work harder, runs up your bill, and drags warm or cool air past the heat exchanger faster than it can do its job.
The Bay Area doesn't have brutal heat or cold, so a 3-month cycle is plenty for most homes. Every month if you have pets or someone with allergies. Always swap before heating season kicks in.
What you’ll need
- A new filter — check the size printed on the side of the old one (e.g. 16×25×1)
- A sharpie to write the install date on the new filter
- A flashlight (the filter slot is often tucked behind the unit)
The basics
- Turn the thermostat off so the blower isn’t pulling debris when you open the slot.
- Slide the old filter out — note the airflow arrow printed on the side.
- Slide the new filter in with the arrow pointing toward the unit.
- Write today’s date on the new filter with the sharpie. Set a reminder for 90 days.
Watch out for
- The old filter is gray after 30 days — too-low MERV or there’s dust ingress, get a pro to check ductwork seams.
- The blower runs constantly without cycling off — control board or thermostat issue, not a filter problem.
- Loud rattle when the blower kicks on — the blower wheel may be off-balance, schedule a tune-up.
Spot something off? Let Odosan diagnose it.
Photo of the old filter (showing the color and dust level) or a photo of the nameplate on the air handler so Odosan can identify the unit.