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Tempstar F9MXE / F9MXT filter sizes: 14 x 25 x 3/4, 16 x 25 x 3/4, 20 x 25 x 3/4 and 24 x 25 x 3/4, as listed in the Tempstar 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 |
|---|
| 14 x 25 x 3/4 |
| 16 x 25 x 3/4 |
| 20 x 25 x 3/4 |
| 24 x 25 x 3/4 |
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 Tempstar F9MXE / F9MXT
Last checked 2026-11-06. Manufacturers revise documents. If your unit's label disagrees, trust the label.
shield. be installed in the common return duct prior to entering the
Supply Air Connections return air opening in any orientation.
For a furnace not equipped with a cooling coil, the outlet duct See Table 6 for recommended filter size details.
shall be provided with a removable access panel. This opening Table 6 Filter Size Information − in. (mm)
shall be accessible when the furnace is installed and shall be of
FURNACE FILTER SIZE
such a size that the heat exchanger can be viewed for possible FILTER
CASING BOTTOM
openings using light assistance or a probe can be inserted for WIDTH SIDE RETURN TYPE
RETURN
sampling the air stream. The cover attachment shall prevent
leaks. 14-3/16 16 x 25 x 3/4 14 x 25 x 3/4
Washable*
Connect supply−air duct to flanges on furnace supply−air (360) (406 x 635 x 19) (356 x 635 x 19)
outlet. Bend flange upward to 90_ with wide duct pliers. (See 17-1/2 16 x 25 x 3/4 16 x 25 x 3/4
Washable*
Figure 24) The supply−air duct must be connected to ONLY (445) (406 x 635 x 19) (406 x 635 x 19)
the furnace supply−outlet−air duct flanges or air conditioning 21 16 x 25 x 3/4 20 x 25 x 3/4
coil casing (when used). DO NOT cut main furnace casing side (533) (406 x 635 x 19) (508 x 635 x 19) Washable*
to atTempstar F9MXE / F9MXT filter sizes: 14 x 25 x 3/4, 16 x 25 x 3/4, 20 x 25 x 3/4 and 24 x 25 x 3/4, as listed in the Tempstar 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. 14 x 25 x 3/4; 16 x 25 x 3/4; 20 x 25 x 3/4; 24 x 25 x 3/4.
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 3/4 in. thick: 14 x 25 x 3/4, 16 x 25 x 3/4, 20 x 25 x 3/4 and 24 x 25 x 3/4. Pending human review; check the excerpt.
Manufacturer document for Tempstar F9MXE / F9MXT (https://www.shareddocs.com/hvac/docs/1011/Public/0F/44001400504.pdf), last checked 2026-11-06.