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Our script found these filter sizes in the Lennox ML180UHE source document's filter table: 14x25x1, 16x25x1, 20x25x1, 24x25x1. This page is pending human review, so check the source excerpt on the page to see which size applies to your cabinet and return.
Auto-extracted · review pending Filter sizes auto-extracted from the manufacturer document.
| Sizes / part numbers found in the source table |
|---|
| 14 X 25 X 1 |
| 16 X 25 X 1 |
| 20 x 25 x 1 |
| 24 x 25 x 1 |
Extracted by script from the linked document. Read the excerpt to see which size applies to which cabinet or return.
General guidance (not from this manual): check monthly and replace 1-in. filters every 1–3 months, or follow the filter maker's guidance and your owner's manual.
Pull the old filter and read the size printed on its frame. Nominal sizes are rounded up: a 15.5 x 24.5 in. filter is sold as 16 x 25.
Your furnace manual lists the filter's dimensions, not its MERV rating. Higher-MERV filters restrict more air. Manufacturers such as Carrier recommend keeping the clean-filter pressure drop under 0.2 in. w.c. (ideally under 0.1). Lennox warns that an over-restrictive filter can trip the high limit in winter and freeze the coil in summer. If you want MERV 11–13, a 4-in. media cabinet is the usual route. Ask an HVAC tech to check static pressure. Nominal sizes are rounded: a filter labeled 16 x 25 x 1 actually measures about 15.5 x 24.5 x 0.75.
Manufacturer document for Lennox ML180UHE
Last checked 2026-10-23. Manufacturers revise documents. If your unit's label disagrees, trust the label.
ENTRY VENT This unit is not equipped with a filter or rack. A field-pro-
PIPE vided high-velocity filter is required for the unit to operate
properly. TABLE 1 lists recommended filter sizes. A filter
must be in place any time the unit is operating.
TABLE 1
Furnace Cabinet Filter Size
Width Side Return Bottom Return
SERVICE PLATFORM
A - 14-1/2” 16 X 25 X 1 (1) 14 X 25 X 1 (1)
B - 17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1)
FIGURE 13
C - 21” 16 X 25 X 1 (1) 20 x 25 x 1 (1)
CAUTION D - 24-1/2” 16 X 25 X 1 (2) 24 x 25 x 1 (1)
If this unit is being installed in a space serviced by an
exhaust fan, power exhaust fan, or other device which IMPORTANT
may create a negative pressure in the space, take care If a highefficiency filter is being installed as part of this
when sizing the inlet air opening. The inlet air opening system to ensure better indoor air quality, the filter must
must be sized to accommodate the maximum volume be properly sized. Highefficiency filters have a higher
of exhausted air as well as the maximum volume of static pressure drop than standardefficiency glass/foam
combustion air required for all gas appliances serviced filters. If the pressure drop is too great, system capacity
by this space. and performance may be reduced. The pressure drop
may also cause the limit to trip more frequently during
WARNING the winter and the indoor coil to freeze in the summer,Our script found these filter sizes in the Lennox ML180UHE source document's filter table: 14x25x1, 16x25x1, 20x25x1, 24x25x1. This page is pending human review, so check the source excerpt on the page to see which size applies to your cabinet and return. 14 X 25 X 1; 16 X 25 X 1; 20 x 25 x 1; 24 x 25 x 1.
General guidance (not from this manual): check monthly and replace 1-in. filters every 1–3 months, or follow the filter maker's guidance and your owner's manual.
Filter sizes are nominal (rounded). A filter sold as 16 x 25 x 1 actually measures about 15.5 x 24.5 x 0.75 in. Buy by the nominal size printed on the frame.
Manufacturer document for Lennox ML180UHE (https://www.lennox.com/dA/9b51323cc2/507103-04a.pdf), last checked 2026-10-23.