What size air filter do I need?

Read the size printed on the frame of the one you are replacing, or measure the slot it sits in. Filter sizes are NOMINAL and rounded - a filter sold as 20x25x1 actually measures about 19-1/2 x 24-1/2 x 3/4. Buy by the nominal size printed on the frame, not by what your tape measure says.

Which way does the arrow point?

Toward the blower - the same direction the air is travelling, away from the return grille. Installed backwards the pleats collapse and airflow drops.

Is a higher MERV always better?

No. MERV measures how fine a particle the filter catches, but finer media also restricts airflow. Most residential blowers are happy at MERV 8 to 11. Going higher than the system was designed for trades dust for airflow problems - long run times, a frozen coil, or short cycling on the limit.

How often should I change it in Dallas?

Check a 1 inch filter monthly and change it every one to three months - sooner with pets or during cottonwood season. A 4 inch media filter usually runs six to twelve months. Dallas dust and a long cooling season are hard on filters.

What is the difference between a 1 inch and a 4 inch filter?

A 4 inch filter holds far more media, so it catches more, restricts airflow less and lasts much longer. It only fits if your cabinet or filter base has a 4 inch slot - a 4 inch filter will not go into a 1 inch rack.

Do you have my size on the shelf?

We stock the common residential sizes. Walk in to 10226 Plano Rd, Suite 104 in Dallas and we will match it, or bring the old filter and we will read the size off the frame for you.

Low Stock

Aprilaire

POPUP2400 – FILTER (REPLACE APRILAIRE 401)

Name: POPUP2400 - FILTER (REPLACE APRILAIRE 401)
Brand: Aprilaire
SKU: RP2400
Price: 44.78 USD
Availability: InStoreOnly

SKU RP2400·Replaces APRILAIRE401, CARRIER, POPUP2400

$44.78

In-store price · paid at counter

Low Stock at our Dallas counter

Tested before you leave. Free at the counter.

In-Store Only — We Don’t Ship

Every part is sold in person at our Dallas counter. No shipping, no online orders. Solo venta en tienda — no hacemos envíos.

Visit our Dallas counter to purchase

10226 Plano Rd, Suite 104 · Dallas TX 75238

Call (214) 340-9421 Get directions

Open now · Closes 7pm·Mon–Fri 10am–7pm · Sat 10am–3pm

Free part testingBench-tested at the counter

27,000+ in stockToday, on the shelf

4.9 · 546 reviewson Google

Since 199828 years on Plano Rd

Pro tip

Bring the old filter in, or a photo of the printed frame - the size on the frame is the number to buy by, not what your tape measure reads. And check the arrow before you slide the new one in: about a third of the restricted-airflow calls we hear about turn out to be a filter installed backwards or a 4 inch filter crammed into a 1 inch rack.

Free Part Testing

27,000+ In Stock

4.9 Stars · 546+ Reviews

Since 1998

🏪 In-Store Pickup Only — We do not offer shipping or online ordering. Visit our Dallas location to purchase.

In Stock

Visit our Dallas store to purchase

Call (214) 340-9421 Get Directions

In Stock — Pick Up at Our Dallas Store

10226 Plano Rd, Suite 104, Dallas TX 75238

Questions? Call or text (214) 340-9421

Mon–Fri 10 am – 7 pm | Sat 10 am – 3 pm

Symptoms of failure

Weak airflow at every vent in the house
System runs longer and longer to hit the setpoint
Evaporator coil freezing up
Furnace short-cycling on the high limit
Dust settling fast after cleaning
You cannot remember the last time it was changed

Seeing these does not always mean this part is the culprit. Bring the old one in and we will meter it at the counter, free, before you buy.

The Honeywell POPUP2400 is a collapsible media filter that replaces the Aprilaire 401 filter. It folds flat for easy handling and pops open when you slide it into the air cleaner cabinet. MERV 11 catches dust, pollen, mold, and pet dander. Replace about once a year.

Specs: MERV 11 rating, collapsible pop-up design, direct replacement for Aprilaire 401

Replaces: POPUP2400, RP2400, 401

Fits: Aprilaire whole-house air cleaners: 2400 series

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

TypePleated air filter
ReplacesAprilaire 401
FitSized to the Aprilaire cabinet - match the Aprilaire model number, not a nominal filter size
Airflow directionArrow points toward the blower

Installing it yourself

Difficulty 1/5Typical time 5 minutes

Turn the system off at the thermostat.
Slide the old filter out and note the AIRFLOW ARROW - it points toward the blower, away from the return.
Check the size printed on the frame. Nominal size (20x25x1) is rounded; actual size is slightly smaller.
Slide the new one in with the arrow pointing the same way.
1" filters: check monthly, change every 1-3 months in Dallas. 4" media filters run 6-12 months.
A higher MERV is not automatically better - too restrictive for your blower and you trade dust for airflow problems.

Power off at the disconnect first, every time. Not sure partway through? Bring it to the counter and we will walk it with you.

$44.78

Low Stock · Dallas counter

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