Trane S9X1D120D5PSBB furnace filter size
This furnace takes a 24 x 25 x 1 filter (downflow top (external) or downflow top (external) return).
Every filter option for this model
| Where return air enters | Filter size (inches) | How many |
|---|---|---|
| downflow top (external) | 24 x 25 x 1 | 1 |
| downflow top (external) | 24 x 25 x 1 | 1 |
Where the filter goes
External to unit; not factory supplied ("Filters are not factory supplied for upflow/downflow furnaces").
The maker does not ship a filter with this furnace. The size above is the maker's recommended size at the furnace; if your home has a filter grille in a wall or ceiling, that grille sets the size instead.
How often to change it
General guidance, not from the maker's table: 1-inch filters every 1 to 3 months; 4- and 5-inch filters every 6 to 12 months. Change sooner with pets, smoking or construction dust.
About this model
| Cabinet width | 24.5 in. |
|---|---|
| Airflow direction | downflow (dedicated) |
| Heat input | 120,000 BTU/hr |
| Model number note | trailing revision letter(s) vary |
| Also sold as | American Standard (same model number; IOM/IG boilerplate: "Trane and American Standard create comfortable...") |
How to read a Trane model number
Source
- Trane Product and Submittal Data S9X1/S9B1 FNR-PSD007C-EN (Aug 2026) (product and submittal data (spec sheet), page 12): document. Read 2026-11-03.
- Installation, Operation, and Maintenance FNR-SVX002B-EN (S9X1/S9X2/S9B1) (Aug 2026) (installation manual (IOM), page 60): document. Read 2026-11-03.
Check that the model number on your furnace label matches, and compare with the size printed on your old filter. If they differ, go by the filter that fits your rack.