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Lennox ML195UH filter sizes: 16 x 25 x 1, 20 x 25 x 1 and 24 x 25 x 1, as listed in the Lennox source document's filter table. Which size fits depends on your cabinet and return. This page is pending human review, so check the source excerpt below.
Auto-extracted · review pending Filter sizes auto-extracted from the manufacturer document.
Last checked against the manufacturer document:
| Sizes found in the source table |
|---|
| 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 ML195UH
Last checked 2026-11-04. Manufacturers revise documents. If your unit's label disagrees, trust the label.
If necessary, run the condensate line into a TABLE 1
condensate pump to meet drain line slope
Furnace Cabinet Filter Size
requirements. The pump must be rated for use
with condensing furnaces. Protect the condensate Width Side Return Bottom Return
discharge line from the pump to the outside to avoid 17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1
freezing.
21” 16 X 25 X 1 (1) 20 X 25 X 1 (1)
6-
Continue with exhaust, condensate and intake
24-1/2” 16 X 25 X 1 (2) 24 X 25 X 1 (1)
piping installation according to instructions.
Duct System
INTAKE PIPE *GAS CONNECTION Use industry-approved standards to size and install the
EXHAUST PIPE supply and return air duct system. Refer to ACCA Manual
D. This will result in a quiet and low-static system that has
*Gas connector may be
uniform air distribution. See figure below for proper duct
used for Canadian installation.
able by local authority
having jurisdiction.
SUPPLY
AIR Install self tapping screws
to seal any potential airLennox ML195UH filter sizes: 16 x 25 x 1, 20 x 25 x 1 and 24 x 25 x 1, as listed in the Lennox source document's filter table. Which size fits depends on your cabinet and return. This page is pending human review, so check the source excerpt below. 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.
Every size found in the source table is 1 in. thick: 16 x 25 x 1, 20 x 25 x 1 and 24 x 25 x 1. Pending human review; check the excerpt.
Manufacturer document for Lennox ML195UH (https://www.lennox.com/dA/a903c34336/507268-03f.pdf), last checked 2026-11-04.