Trane furnace filter sizes
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How to read a Trane model number
Trane, American Standard and RunTru furnaces use the same model numbers apart from the first letter. In the tables, stated means a Trane document spells the rule out, and seen in model lists means the pattern holds across Trane's own lists but no Trane chart says so.
Trane / American Standard (legacy letter-coded families, ~1992-2020: XR80, XB80, XT80, XV80, XB90, XR90, XL90, XR95, XT95, XV95, XC95, XC95m)
| Position | What it means | Basis |
|---|---|---|
| 1 | Brand. T = Trane, A = American Standard. Otherwise identical model. | stated |
| 2 | Airflow. U = upflow/horizontal, D = downflow/horizontal. | stated |
| 3 | Efficiency/heat-exchanger line. Seen: D = 80% induced draft (XR80/XT80/XV80), E = 80% (XB80), C = 90% condensing (XB90), X = 90% direct vent condensing (XR90/XL90), H = 95% condensing (XR95/XT95/XV95/XC95/XC95m). | seen in model lists |
| 4 | Stages: 1 = single stage, 2 = two stage, 3 = three stage, M = modulating (TUHM/TDHM). | seen in model lists (matches document titles: XL90 'Two Stage', XC95 '3 Stage', XC95m 'Modulating') |
| 5 | Cabinet width: A = 14-1/2 in, B = 17-1/2 in, C = 21 in, D = 24-1/2 in. This is the key for the filter size. | stated |
| 6 to 8 | Nominal input in thousands of BTU/h (040 = 40,000). Exceptions in the docs: XR95/XT95 TUH1B080 lists 77,000 input; XT95 TDH1B065 lists 60,000 input; XR95 TDH1C085/TDH1D110 inputs as printed. | stated (input row of each spec table) |
| 9 onward | Gas/electrical and blower/airflow code plus design revision letter (e.g. A9241B, A9V3VB, ACV3VA, A9H31B). 'H' in the 10th position marks the 'High Efficiency' XT80/XT95 lines; 'V' marks variable-speed blower; 'AFV' marks the whole-house-air-cleaner versions. The last letter is a revision and does not change the filter size within a document. | seen in model lists |
Example: TUD1B080A9361B reads as: Trane, upflow/horizontal, 80% single stage (XR80), 17-1/2 in cabinet, 80,000 BTU/h input.
Trane / American Standard S-Series (2016-2026: S8X1, S8X2, S8B1, S8V2, S9X1, S9X2, S9B1, S9V2, S9VM) and L8V1
Brand note: Same model numbers are used for both Trane and American Standard; documents carry the line 'About Trane and American Standard Heating and Air Conditioning' (e.g. IOM FNR-SVX008A-EN).
| Position | What it means | Basis |
|---|---|---|
| 1 | S = S-Series (L = L8V1 ultra-low-NOx line). | seen in model lists |
| 2 | Efficiency class: 8 = 80% AFUE, 9 = 90%+ condensing. | seen in model lists (matches PSD titles and AFUE rows) |
| 3 | Model tier/motor: X = standard (High Efficiency Motor), B = builder grade, V = variable speed blower. | seen in model lists (Handbook 22-8301-39 names S8B1/S9B1 'Builder-Grade', S9V2 'Variable Speed') |
| 4 | 1 = single stage, 2 = two stage, M = modulating (S9VM). | seen in model lists (Handbook family names, e.g. '80 Single-Stage Gas Furnace (S8X1)', '80 Two-Stage Gas Furnace (S8X2)') |
| 5 | Cabinet width: A = 14.5 in, B = 17.5 in, C = 21 in, D = 24.5 in. | stated |
| 6 to 8 | Input in thousands of BTU/h (026 = 26,000; 120 = 120,000). | stated (input rows of PSD tables) |
| 9 | Configuration: M = multiposition (upflow/downflow/horizontal), U = upflow convertible to horizontal, D = dedicated downflow. | stated (PSD009D/011C/007C cover pages: 'Upflow, Convertible to Horizontal...' list U models; 'Downflow Only' lists D models) |
| 10 | Nominal cooling airflow in tons (2-5). | stated (Handbook 22-8301-39 'Airflow In Tons' column matches this digit, p73-83) |
| 11 onward | Motor/control and revision code, e.g. PS, PT, VS, VC, PC/PD (S8V2-C communicating). Final letter(s) = revision (A, B, C...). | seen in model lists |
How it connects to the filter: S8 (multiposition) families: 14.5 in gives 14x25x1, 17.5 gives 16x25x1, 21 gives 20x25x1, 24.5 gives 24x25x1 (single filter). S9 upflow: 16x25 / 20x25 / 24x25. S9 downflow: documents conflict (2 x 14x20 or 2 x 16x20 in PSD011C, handbook and 2020-22 guides; 1 x 16x25 / 20x25 / 24x25 in the 2026 IOMs).
Example: S9X2B060U4PSBB reads as: S-Series 90%+, two stage, 17.5 in cabinet, 60,000 BTU/h, upflow/horizontal, 4-ton airflow.
RunTru by Trane (A801X, A951X, A952V)
Brand note: Listed in the RunTru section (RTFUR) of the 2026 Trane handbook 22-8301-39 p287-289; PSD/IOM documents carry Trane/American Standard boilerplate.
| Position | What it means | Basis |
|---|---|---|
| 1 to 4 | A + efficiency + stages + motor: A801X = 80% single stage ECM, A951X = 95% single stage ECM, A952V = 95% two-stage variable speed. | stated (handbook headings 'A801X - Single Stage, ECM', 'A951X - Single Stage, ECM', 'A952V - Two Stage, Variable Speed ECM') |
| 6 to 8 | Input in thousands of BTU/h (A801X040 = 40,000). | stated (handbook input column) |
| 9 | Cabinet width letter A/B/C/D = 14.5/17.5/21/24.5 in (note: here the width letter comes AFTER the BTU digits). | stated (handbook width column p287-289) |
| 10 | M = multiposition, U = upflow/horizontal, D = downflow. | stated (PSD cover pages) |
| 11 | Airflow tons. | seen in model lists |
| 12 onward | S/T variant (A801X: SD vs TD share a spec column) + revision letters. | seen in model lists |
Example: A801X080BM4SDB reads as: RunTru 80% single stage, 80,000 BTU/h, 17.5 in cabinet, multiposition, 4-ton airflow.