HVAC Decoder
Trane Tonnage From Model Number
Where Trane puts the capacity code, what each code means, and the readings that look like capacity but are not. Read out of 3 documents Trane publishes itself, named further down with the date each was fetched.
Starting the decoder. The capacity tables below this box are already loaded, so you can read your code off them now.
Nominal capacity from a model number is a nameplate convention, not a measurement. Actual delivered capacity depends on the matched indoor unit, line set, airflow and conditions. Confirm against the data plate's BTU/h rating and the AHRI certificate for the matched system.
Trane Capacity Codes and Tonnage
R-410A generation
Capacity sits at positions 7-8. Position 6 is the field-connection digit, not part of the capacity, and position 1 is the refrigerant. Example: 4TTR4036N1000.
| Code | Nominal BTU/h | Tons | Code / 12 |
|---|---|---|---|
| 12 | 12,000 | 1 | same answer |
| 18 | 18,000 | 1.5 | same answer |
| 19 | 18,000 | 1.5 | 1.58, so the division is wrong here |
| 24 | 24,000 | 2 | same answer |
| 25 | 24,000 | 2 | 2.08, so the division is wrong here |
| 30 | 30,000 | 2.5 | same answer |
| 31 | 30,000 | 2.5 | 2.58, so the division is wrong here |
| 36 | 36,000 | 3 | same answer |
| 37 | 36,000 | 3 | 3.08, so the division is wrong here |
| 42 | 42,000 | 3.5 | same answer |
| 43 | 42,000 | 3.5 | 3.58, so the division is wrong here |
| 48 | 48,000 | 4 | same answer |
| 49 | 48,000 | 4 | 4.08, so the division is wrong here |
| 60 | 60,000 | 5 | same answer |
| 61 | 60,000 | 5 | 5.08, so the division is wrong here |
Table transcribed from Product and Submittal Data, Outdoor Unit 5HCL9 (DLR-PSD004A-EN, February 2026), fetched from elibrary.tranetechnologies.com on 2026-07-24.
R-454B generation
Capacity sits at positions 7-8 again, but positions 2-3 become a two letter system type (HP heat pump, HC cold climate heat pump) instead of the brand letter and unit type. Example: 5HCL5060B1000A.
| Code | Nominal BTU/h | Tons | Code / 12 |
|---|---|---|---|
| 12 | 12,000 | 1 | same answer |
| 18 | 18,000 | 1.5 | same answer |
| 19 | 18,000 | 1.5 | 1.58, so the division is wrong here |
| 24 | 24,000 | 2 | same answer |
| 25 | 24,000 | 2 | 2.08, so the division is wrong here |
| 30 | 30,000 | 2.5 | same answer |
| 31 | 30,000 | 2.5 | 2.58, so the division is wrong here |
| 36 | 36,000 | 3 | same answer |
| 37 | 36,000 | 3 | 3.08, so the division is wrong here |
| 42 | 42,000 | 3.5 | same answer |
| 43 | 42,000 | 3.5 | 3.58, so the division is wrong here |
| 48 | 48,000 | 4 | same answer |
| 49 | 48,000 | 4 | 4.08, so the division is wrong here |
| 60 | 60,000 | 5 | same answer |
| 61 | 60,000 | 5 | 5.08, so the division is wrong here |
Table transcribed from Inverter Side Discharge Heat Pump 5HCL5 (ODR-PSD038A-EN, December 2025), fetched from elibrary.tranetechnologies.com on 2026-07-24.
The Trane codes that dividing by 12 gets wrong
The usual shortcut is that a capacity code is the nominal BTU/h divided by 1,000, so dividing it by 12 gives the tonnage. Trane prints 7 codes where that arithmetic disagrees with Trane's own table, and the table is what the equipment is sold against:
| Code | Trane prints | Code / 12 gives |
|---|---|---|
| 19 | 1.5 tons | 1.58 |
| 25 | 2 tons | 2.08 |
| 31 | 2.5 tons | 2.58 |
| 37 | 3 tons | 3.08 |
| 43 | 3.5 tons | 3.58 |
| 49 | 4 tons | 4.08 |
| 61 | 5 tons | 5.08 |
These are not derivable, only transcribable, which is why this decoder carries Trane's printed table rather than a formula. If you meet one of these codes in the field, arithmetic will land you between two real sizes, and the printed table is the only thing that resolves it.
Worked example: Trane 4TTR4036N1000
Capacity code 36 at characters 7-8 of 4TTR4036N1000: 36,000 BTU/h, which is 3 tons at 12,000 BTU/h per ton. Positions 7-8 are the nominal capacity code in Trane's own model nomenclature; position 6 is the field-connection digit, not part of it.
- Refrigerant: R-410A. Position 1 digit 4 (2 = R-22, 4 = R-410A, 5 = R-454B).
- Brand letter: Trane. Position 2 letter T (T = Trane, A = American Standard).
- Product type: Split AC condenser. Position 3 character T.
- Efficiency: SEER class 14. Position 5 is the family SEER (0 = 20, 3 = 13, 4 = 14, 5 = 15, 6 = 16, 8 = 18, 9 = 19).
Trane has 2 documented layouts: R-410A generation reads capacity at positions 7-8; R-454B generation reads capacity at positions 7-8. They agree on where the capacity sits and differ in what the surrounding positions mean, so the size decodes the same way on both while the refrigerant and efficiency digits do not.
What is specific to Trane
The Trane documents behind this page
Fetched from trane.com on 2026-07-24. Covers the R-410A position layout, from a Model Nomenclature diagram that numbers its own positions 1-15: position 5 Family SEER, position 6 Split System Connections (0 = Brazed), positions 7-8 Nominal Capacity in 000s of BTUs. This is the only R-410A-generation document on this page.
Fetched from elibrary.tranetechnologies.com on 2026-07-24. Covers the explicit Digit 7, 8 Nominal Tonnage table, including every code the divide-by-12 rule gets wrong. The table is Trane's shared capacity table and the engine applies it to both generations; this document itself is an R-454B sheet.
Fetched from elibrary.tranetechnologies.com on 2026-07-24. Covers the R-454B system-type letters and the Digit 5 Nominal Rated SEER2 map, for heat pumps. Its capacity table is the same manufacturer boilerplate as the sheet above rather than an independent second reading of it.
Frequently asked questions
How do I find the tonnage of a Trane unit from the model number?
Read the capacity code: on Trane it sits at positions 7-8. Position 6 is the field-connection digit, not part of the capacity, and position 1 is the refrigerant. On 4TTR4036N1000 that code is 36, which is 36,000 BTU/h, or 3 tons, because one ton of cooling is 12,000 BTU/h. Use the OUTDOOR unit's model number for system cooling capacity; the indoor air handler or coil carries its own number. This position comes from Trane's own 22-1904-1M-EN, not from a third-party chart.
Can I just divide the Trane capacity code by 12?
Not on every code. Trane prints 7 capacity codes where that division gives the wrong answer: 19 is 1.5 tons where dividing gives 1.58, 25 is 2 tons where dividing gives 2.08, 31 is 2.5 tons where dividing gives 2.58, 37 is 3 tons where dividing gives 3.08, 43 is 3.5 tons where dividing gives 3.58, 49 is 4 tons where dividing gives 4.08, 61 is 5 tons where dividing gives 5.08. Those values come from Trane's own printed table rather than from arithmetic, which is the whole reason the table exists. On every other code in the table the division does work.
Where is the model number on a Trane unit?
On the data plate on the outdoor unit's side panel, labeled M/N or MODEL, usually directly above the serial numbe. It is labeled M/N, MODEL or MODEL NO., usually printed directly above or beside the serial number. The model number describes what the unit is, including its capacity. The serial number describes when it was built and carries no capacity information at all.
Which Trane document is this based on?
Product Data 4TTR4-L Split System Air Conditioner (22-1904-1M-EN), fetched from trane.com on 2026-07-24, which covers the R-410A position layout, from a Model Nomenclature diagram that numbers its own positions 1-15: position 5 Family SEER, position 6 Split System Connections (0 = Brazed), positions 7-8 Nominal Capacity in 000s of BTUs. This is the only R-410A-generation document on this page. Product and Submittal Data, Outdoor Unit 5HCL9 (DLR-PSD004A-EN, February 2026), fetched from elibrary.tranetechnologies.com on 2026-07-24, which covers the explicit Digit 7, 8 Nominal Tonnage table, including every code the divide-by-12 rule gets wrong. The table is Trane's shared capacity table and the engine applies it to both generations; this document itself is an R-454B sheet. Inverter Side Discharge Heat Pump 5HCL5 (ODR-PSD038A-EN, December 2025), fetched from elibrary.tranetechnologies.com on 2026-07-24, which covers the R-454B system-type letters and the Digit 5 Nominal Rated SEER2 map, for heat pumps. Its capacity table is the same manufacturer boilerplate as the sheet above rather than an independent second reading of it. Every capacity value on this page traces to one of those documents, and each is named with the date it was fetched so you can pull it yourself.
Is the decoded tonnage the size I should install?
No. Nominal tonnage is what the unit was built to deliver, not what the building needs, and the old unit may have been oversized or sized before insulation and window changes. Treat it as a starting clue and run a load calculation before matching a replacement. Actual delivered capacity also depends on the matched indoor unit, line set, airflow and conditions.
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Other brands with their own manufacturer nomenclature document: Carrier tonnage by model number, Lennox tonnage by model number, Goodman tonnage by model number, Amana tonnage by model number.
Got the tonnage? Check it against the actual load.
The old unit's nominal size is a clue, not a load calculation. Oversized systems short-cycle and dehumidify poorly. Run the numbers before you match a replacement.