Fresh HVAC filter, and learn your size
One-time · any month works
Why it matters
Of everything you inherited from the sellers, the HVAC filter is the item you can reset to factory-new for ten bucks — and one of the most revealing. A reasonably clean filter says the system was cared for. A filter caked gray-black says every "regularly serviced!" claim in the listing deserves a skeptical read, and the rest of your punch list just got more important.
What skipping it costs
$150–$2,000
You have no idea when the sellers last changed this filter — and a choked filter is the number-one preventable killer of blower motors and the cheapest way to freeze an AC coil. The tell works both ways: pull a filter black with neglect and you've just learned something about how everything else in the house was maintained.
Two ways to get it done
Do it yourself
You'll need: One new filter in your size (~$8–$20 — the size is printed on the old one's frame).
- Find the filter: at the air handler/furnace (a slot with a thin door) or behind a return grille in a wall or ceiling. Some houses have BOTH — check.
- Pull the old one and read the frame: size (like 20×25×1) and orientation arrow. Write the size into your house profile in this app — that's the whole trick that makes the rest of the year effortless.
- Slide the new one in, arrow pointing toward the blower (with the airflow, into the duct).
- Date the frame edge with a marker. The recurring filter card takes over from here.
- On MERV: 8–11 is the sweet spot for most homes. Ultra-high MERV in a system not designed for it chokes airflow — more filter is not automatically better.
Hire it out
$75–$150National fair range — local labor moves this number.
There's nothing to hire for a filter — but if an HVAC tech is already at the house for the seasonal checkup, have them point out every filter location and size in the system ($75–$150 buys the full first-visit once-over). Skip the filter-subscription pitch unless the per-filter price actually beats the hardware store, which it usually doesn't.
Ask the tech
- Where are ALL the filter locations in this system? (Some houses have return-grille filters you'd never find.)
- What size and MERV do you recommend for this specific blower?
Red flags you're being upsold
- A filter-subscription upsell at triple the hardware-store price for the same filter.
- 'Your system is too old for good filters' — MERV guidance depends on the blower, not a sales calendar.
The call
DIY, this week. It's ten minutes, it resets the clock to a known date, and the size you write down makes every future change a two-minute errand.