RunTru by Trane furnace filter sizes
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How to read a RunTru by 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.
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.
Related families from the same maker group
These share parts of the numbering system with RunTru, so they can help with an older or rebadged label.
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.