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Change the Furnace Filter Before Winter: The Amazon Basics MERV 11 Filter, a Marker for the Date, and an Air Purifier for the Bedroom

By Best Items Staff
A close-up in a basement utility room in early November: a pair of hands in a flannel shirt sliding a fresh white pleated air filter into the slot of a furnace, the dusty grey old filter leaning against the wall beside it, a black marker resting on top of the furnace cabinet and a handwritten date visible on the new filter's cardboard frame, a bare bulb and a small window casting soft grey light, candid editorial

The first weeks of steady heating season are a good time for one of the easiest home maintenance jobs there is: swapping the furnace filter. It takes a couple of minutes, needs no tools, and a clean filter helps your system move air the way it's designed to. Here's how to do it, what the Amazon Basics 20x20x1 MERV 11 Air Filter offers, and two small extras that make the habit stick.

What the Amazon Basics MERV 11 filter is

Amazon Basics 20x20x1 MERV 11 Air Filter, 6-Pack, AC and Furnace Filters is a pleated, disposable filter for standard furnaces, central AC, and HVAC return grilles. Per its product page, its electrostatically charged synthetic media captures household dust, lint, pollen, and pet dander as small as 3 microns, and a wire-mesh-backed frame helps it hold its shape. The nominal size is 20x20x1; the actual dimensions are 19.75 x 19.75 x 0.75 inches, which is normal for filters. The 6-pack covers up to a year if you change it every 60 to 90 days. Catalog rating: 4.7 / 5.0.

Prices on the site update daily, so check the product page for the current price.

First, check your size and your system

Before you buy anything, pull out the filter you have now and read the size printed on its frame. Filters are sold by nominal size, so if yours says 20x20x1, this pack fits. If it says 16x25x1 or 20x25x4, you need a different filter. It's also worth a quick look at your furnace manual: MERV 11 is a finer filter than the basic fiberglass kind, and most residential systems handle it fine, but some older or smaller systems recommend a specific MERV range. If yours does, follow it.

How to swap the filter in two minutes

Turn the thermostat off (or set the system to off) so the blower isn't running. Find the filter slot, usually on the furnace cabinet near the blower or behind a return-air grille in a wall or ceiling. Slide out the old filter and note which way its airflow arrow points. Slide the new one in with the arrow pointing the same way, toward the furnace and away from the return, and make sure it sits flat with no gaps around the edges. Close the slot or grille and turn the system back on. If the old filter is grey and caked with dust, you may want to check it sooner next time, especially in a home with pets.

Write the date on it: Sharpie Fine Point Permanent Markers

The hardest part of filter maintenance is remembering when you last did it. The fix is simple: write the install date on the new filter's frame before it goes in. Sharpie Permanent Markers, Fine Tip, Black, 12 Count are made for exactly that kind of job. Per the product page, they make bold, quick-drying marks that resist fading and water on paper, plastic, metal, wood, and more. Keep one on top of the furnace or tucked into the box of spare filters, and write the date on the box too. Catalog rating: 4.8 / 5.0.

For the bedroom: Levoit Core 200S-P Smart Air Purifier

A furnace filter cleans the air that passes through your heating system, and only while the blower is running. A small air purifier works on one room all the time. Levoit Core 200S-P Smart Air Purifier for Home Bedroom & Pets is a compact unit that, per its product page, clears pet dander, dust, and odors in bedrooms and dorms, with app and voice control and quiet enough operation for overnight use. It's a good add-on if someone in the house is bothered by dust or a pet that sleeps on the bed. It doesn't replace the furnace filter; the two do different jobs. Catalog rating: 4.5 / 5.0.

Who it's for, and who should skip it

The MERV 11 6-pack is a good fit if your furnace takes a 20x20x1 filter and you want a year of changes in one box. Skip it if your filter slot is a different size, your system calls for a thicker media filter, or your manual recommends a lower MERV rating. If you rent, check with your landlord about who handles filter changes; many leases put it on the tenant.

The bottom line

Changing the furnace filter is one of the quickest jobs on the winter list. The Amazon Basics 20x20x1 MERV 11 6-pack covers up to a year of swaps, a Sharpie fine tip marker turns "when did I change this?" into a date on the frame, and a Levoit Core 200S-P adds a little extra help in the bedroom. Check your filter size first, and check each product page for the current price.