HVAC

How Often Should You Change Your Furnace Filter?

A clogged filter is the single most common — and most preventable — cause of HVAC trouble. Here's how often to swap it, and how to never forget.

The short answer

For a standard 1-inch pleated filter, replace it every 90 days as a baseline. Move to every 60 days if you have pets, and every 30 days during heavy heating or cooling months or if anyone in the home has allergies. Thicker 4- to 5-inch media filters can last 6 to 12 months.

Why it matters more than people think

The filter protects the blower and coil, not just your air. When it clogs, the system pulls harder, runs longer, and burns more electricity — a dirty filter can add noticeably to your energy bill. Worse, restricted airflow makes the system overheat or the coil freeze, and that's how a $15 filter turns into a service call.

What the MERV rating means

MERV measures how much a filter traps. Higher isn't always better — a too-restrictive filter can starve airflow on residential systems.

• MERV 8: solid everyday choice — dust, lint, pollen.
• MERV 11: better for pets and mild allergies.
• MERV 13: fine particles and smoke; confirm your system can handle it.

How to change it (2 minutes)

1. 1Turn the system off at the thermostat.
2. 2Find the filter slot — usually in the return duct or the air handler.
3. 3Note the airflow arrow on the old filter, then slide the new one in facing the same way.
4. 4Turn the system back on. Done.

Never forget again

The reason filters get skipped isn't difficulty — it's memory. Upkeepery tracks your filter (and its size, so reordering is one tap) and reminds you before it's due, so a small habit protects an expensive system.