Brands › RunTru by Trane › A951X
RunTru by Trane A951X080BU4SAC furnace filter size
This furnace takes a 16 x 25 x 1 filter (not stated (spec table, upflow model) or upflow (bottom or side opening; external) return).
Every filter option for this model
| Where return air enters | Filter size (inches) | How many |
|---|---|---|
| not stated (spec table, upflow model) | 16 x 25 x 1 | 1 |
| upflow (bottom or side opening; external) | 16 x 25 x 1 | 1 |
Where the filter goes
External to unit; not factory supplied.
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 | 17.5 in. |
|---|---|
| Airflow direction | upflow/horizontal |
| Heat input | 80,000 BTU/hr |
| Efficiency (AFUE) | 96.0% |
| Model number note | trailing revision letter(s) vary |
How to read a RunTru by Trane model number
Source
- Product and Submittal Data A951X FNR-PSD016B-EN (May 2026) (product and submittal data (spec sheet), page 8): document. Read 2026-11-03.
- Installation, Operation, and Maintenance FNR-SVX004B-EN (A951X) (Sep 2026) (installation manual (IOM), page 47): 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.