Filter changes that actually help (and the ones that don't)
MERV ratings are a marketing minefield. Here's what we put in our own homes, and the inexpensive habit that prevents 80% of the call-backs we see.
- Author
- Maya R.
- Role
- Service tech
- Published
- November 5, 2025
- Reading time
- 6 min
If you only do one thing in 2026 to keep your furnace healthy: write the filter date on the filter when you put it in. That's it.
The MERV trap
Higher MERV is not always better. A MERV 16 filter in a system designed around MERV 8 will choke airflow, freeze your AC coil in summer, and overheat your heat exchanger in winter. We see this every season.
Our default
- 1" filters: MERV 11, swapped every 60 days
- 4" media filters: MERV 13, swapped every 6 months
- Pet households: shorten by 30 days
- Recent renovation dust: shorten to 30 days for 4 months, then return to baseline
The habit that prevents the most damage
Write the install date on the filter with a marker. That's the entire trick. Pet hair builds up faster than you think — we've pulled 1" filters that were technically rated for 90 days but were 70% blocked at 45 days because the dog was shedding for spring.
What's not worth it
We don't recommend washable electrostatic filters for whole-home systems. They look thrifty but we've replaced too many heat exchangers behind "never had to change the filter" for years. Disposable is better — change it on a calendar.
Want this kind of read every quarter?
Four short emails a year. Mostly seasonal tips. Easy unsubscribe.
Have a question this didn't answer?
The dispatch line is the fastest way to get a real answer.
