Brands › American Standard › XT80 (TDD1 -H)
American Standard ADD1D120A9H51B furnace filter size
This furnace takes 2 filters, each 16 x 20 x 1 (downflow top (external, in return duct) or downflow top (external, in return duct)).
Every filter option for this model
| Where return air enters | Filter size (inches) | How many |
|---|---|---|
| downflow top (external, in return duct) | 16 x 20 x 1 | 2 |
| downflow top (external, in return duct) | 16 x 20 x 1 | 2 |
Where the filter goes
Downflow: two filters factory supplied, mounted outside cabinet in return duct with supplied brackets.
The maker ships a filter with this furnace.
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/horizontal |
| Heat input | 120,000 BTU/hr |
| Efficiency (AFUE) | 80.0% |
| Model number note | trailing revision letter varies Same furnace as Trane TDD1D120A9H51B, per the maker's document. |
| Also sold as | Trane TDD1D120A9H51B |
How to read a American Standard model number
Source
- Trane Product Data XT80 TUD1/TDD1 (-H) Pub. 22-1779-10 (2015) (product data (spec sheet), page 8): document. Read 2026-11-03.
- Installer's Guide 18-CD21D1-15-EN (*UD1/*DD1 -H, XT80) (2015, scanned) (installation manual, page 13): 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.