How Often Should You Really Change Your Furnace Filter?

The filter is the cheapest part of your HVAC system. It's also the part most homeowners ignore until something breaks. Here's the truth: the "change every 90 days" sticker on the package is a rough guideline written for an average home, and you probably aren't average.

Here's how to actually figure out how often your filter needs changing — and what types are worth using.

The standard recommendations (and when they're wrong)

Filter type	Standard interval	When to change more often
1-inch fiberglass (cheap)	30 days	Almost always — these are barely filters
1-inch pleated	60–90 days	Pets, allergies, dust, or running blower constantly
4-inch or 5-inch pleated	6–12 months	Heavy use seasons
Washable	Monthly cleaning	Most residential — but check the seal

If you have pets that shed, halve the interval. If anyone in your house has allergies or asthma, halve it again. If you live near a busy road or active construction, halve it once more. We've serviced homes in Latham where filters were unrecognizable after 45 days because of nearby construction dust.

The eyeball test that beats any schedule

Pull the filter out and hold it up to a light. If you can barely see light through it, it's overdue. If it's visibly grey but light passes through clearly, you have another month. If it looks new, you're either over-changing or your system isn't pulling much air.

This 30-second check beats any schedule on the box. Do it monthly during peak heating and cooling seasons.

Filter ratings — what MERV actually means

MERV stands for "Minimum Efficiency Reporting Value" and measures how well a filter traps small particles. Higher MERV catches smaller particles. Most residential systems work best with MERV 8 to 13:

• MERV 1–4: cheap fiberglass — protects the furnace, doesn't clean air

• MERV 5–8: standard pleated — good general-purpose

• MERV 9–12: better allergy and dust capture

• MERV 13+: hospital-grade; check your system's pressure drop rating before using

Common mistake: installing a MERV 16 filter in a residential system. The filter restricts airflow so much that the blower works harder, energy bills rise, and the indoor coil can freeze. Stick to MERV 8–13 for most Albany homes unless your HVAC was specifically designed for higher.

Why do filters matter more in winter than summer in Albany

A common misconception is that filters mainly help in summer. In our climate, winter is harder on filters:

• Windows are sealed shut for months — indoor dust accumulates

• Forced-air heating cycles run far more often than cooling cycles

• Dry winter air carries more static-charged particles

If you only remember one filter change, do it before October.

The "always-on fan" question

Some homeowners run their thermostat fan in "On" mode 24/7, believing it improves air quality. It does — at the cost of much faster filter loading, higher electric bills, and increased humidity in summer.

A better setup: use "Auto" mode normally, then switch to "On" for an hour or two when you want air circulation (after cooking, after pets shed, during pollen season).

What about washable filters?

Washable filters sound great in theory: rinse monthly, never buy filters again. In practice, three issues come up repeatedly:

1. They never seal as well as disposable filters. Air bypasses around the edges, reducing filtration.

2. They mildew if not fully dry before reinstalling. Then they spread mold spores through your home.

3. They lose efficiency over years. The fibers degrade.

We don't recommend them for most Albany homes. The few dollars saved aren't worth the headaches.

Set a calendar reminder

Honest fact: if you don't make filter changes automatically, they won't happen. Pick a system:

• Monthly calendar reminder on your phone

• Sign up for an Amazon "subscribe and save" delivery

• Add it to your maintenance plan

We change filters on every maintenance visit for plan members, so for the 75% of homeowners who'd otherwise forget, plan membership solves it permanently.

A clean filter pays for itself

A 1-inch pleated filter costs $5–$15. Running your furnace with a clogged filter can spike heating bills by 5–15% and shorten the lifespan of your blower motor. The economics aren't close.

Have questions about your specific system? Call (838) 267-4484 or ask during your next tune-up.