Trane model number tonnage

On a Trane air conditioner or heat pump, characters 7 and 8 of the model number give the size in thousands of BTU per hour. Divide by 12 for tons: 4TTR7036A1000B is 36,000 BTU/h, a 3-ton unit. Trane gas furnaces carry the heating input at characters 6 to 8: S9X2B060 is the 60,000 BTU/h size.

Decode a Trane model number

Look for “Model”, “M/N” or “MOD” on the rating plate. For air conditioner tonnage, read the plate on the outdoor unit. What you type stays in your browser.

The decoder on this page also reads American Standard model numbers, which follow the same or closely related layouts.

What do the size codes mean?

On an air conditioner or heat pump the code is the nominal cooling capacity in thousands of BTU per hour. One ton of cooling is 12,000 BTU/h, so the code divided by 12 is the tonnage. Some series print the code with a leading zero: 036 and 36 are the same size.

CodeNominal BTU/hTonsVariant codes in the same size class
18 or 01818,0001.517, 19
24 or 02424,000225
30 or 03030,0002.531
36 or 03636,000337, 38
42 or 04242,0003.541, 43
48 or 04848,000447, 49
54 or 05454,0004.5
60 or 06060,000559, 61

A variant code marks a slightly different version of the same size class. Not every brand uses every code.

On a gas furnace the code is the heating input in thousands of BTU per hour, always three digits: 040 is 40,000 BTU/h, 060 is 60,000, 080 is 80,000, 100 is 100,000 and 120 is 120,000. It is input, not output, and it is not tons.

Where is the tonnage in a Trane model number?

It depends on the series. Find the layout that matches the start of your model number.

In the examples, an asterisk stands for a character that varies from one version of the model to the next.

From the manufacturer’s document

Trane air conditioners and heat pumps, 4T and 5T numbers

Characters 7 and 8, after the zero at character 6.

4TTtypeRfamily7SEER036sizeA1000B
Example: model 4TTR7036A1000B reads as 3 tons (36,000 BTU/h nominal).

More from the same documents: 4TWR6048A1000A is 4 tons.

CharactersMeaning
1Refrigerant: 4 = R-410A. Current R-454B models start with 5
2T = Trane
3Product type: T = split cooling (air conditioner), W = split heat pump
4Product family: Z = Leadership two stage, X = Leadership, R = replacement/retail, M or B = basic
5Family SEER: 3 = 13, 4 = 14, 5 = 15, 6 = 16, 8 = 18, 9 = 19, 0 = 20
6Refrigerant connections: 0 = brazed
7-8Nominal capacity in thousands of BTU/h
9Major design modification
10Power supply: 1 = 200-230 V or 208-230 V, single phase

Trane’s product data prints the legend for 4-series (R-410A) outdoor units. The 5-series R-454B numbers keep the same positions: Trane’s catalog lists the tonnage for each one and certified ratings agree. Checked on October 5, 2026: 160 of 160 models in the DOE certification database and 39 of 39 in the ENERGY STAR list read to the certified size.

Manufacturer listings and certified ratings

Trane variable-speed air conditioners and heat pumps (X at character 6)

Characters 7 and 8, after the X at character 6.

5TTtypeVfamily8SEERX36sizeA1000A
Example: model 5TTV8X36A1000A reads as 3 tons (36,000 BTU/h nominal). The product data on Trane’s page lists this model at 3 tons.

Trane’s catalog lists the tonnage next to each of these model numbers, and certified ratings agree. Trane’s printed legend does not explain the X. Checked on October 5, 2026: 28 of 28 models in the DOE certification database and 19 of 19 in the ENERGY STAR list read to the certified size.

Manufacturer listings and certified ratings

American Standard air conditioners and heat pumps, 4A and 5A numbers

Characters 7 and 8, after the zero or X at character 6.

5A7typeAfamily6SEER036sizeA1000A
Example: model 5A7A6036A1000A reads as 3 tons (36,000 BTU/h nominal). The product data on American Standard’s page lists this model at 3 tons.

American Standard’s catalog lists the tonnage next to each model number, and certified ratings agree. The positions are the same as in Trane’s legend, with A in place of T. Checked on October 5, 2026: 141 of 141 models in the DOE certification database and 42 of 42 in the ENERGY STAR list read to the certified size.

Checked against certified ratings

Trane and American Standard numbers that start N5, E4, A5 or 5H

Characters 7 and 8, after the zero at character 6.

N5AC3series036sizeB1
Example: model N5AC3036B1 reads as 3 tons (36,000 BTU/h nominal). The DOE certification database lists it at 30,000 to 36,000 BTU/h of cooling, depending on the indoor unit.

No Trane document covers these newer numbers. They keep the size at characters 7 and 8, and that was checked against certified ratings. Checked on October 5, 2026: 99 of 101 models in the DOE certification database and 36 of 38 in the ENERGY STAR list read to the certified size.

Where is the size in a Trane furnace model number?

From the manufacturer’s document

Trane gas furnaces, TU and TD numbers

Characters 6 to 8, after the cabinet-width letter.

TUdirectionDtype1stagesBwidth080inputA9H31AA
Example: model TUD1B080A9H31AA reads as 80,000 BTU/h input. The sample number in Trane’s own legend.
CharactersMeaning
1-2Configuration: TU = upflow/horizontal, TD = downflow/horizontal
3Type: E or D = 80% induced draft, C or X = 90% condensing, H = 95% condensing
4Heating stages: 1 = single, 2 = two stage, M = modulating
5Cabinet width: A = 14.5 in, B = 17.5 in, C = 21.0 in, D = 24.5 in
6-8Heating input in thousands of BTU/h (080 = 80,000)
9Major design change
10Voltage and controls
11-12Air capacity for cooling: 36 = 3 tons, V3 = 3 tons variable speed, and so on. This is blower size, not heating capacity

Trane’s product data prints the legend: heating input in thousands of BTU/h at characters 6 to 8. Checked on October 5, 2026: 12 of 12 models in the DOE certification database read to the certified size.

From the manufacturer’s document

Trane and American Standard S8 and S9 gas furnaces

Characters 6 to 8, after the cabinet-width letter.

S9X2seriesBwidth060inputU4PSBA
Example: model S9X2B060U4PSBA reads as 60,000 BTU/h input. Trane’s table lists 60,000 BTU/h for the second stage and 39,000 for the first.

More from the same documents: S9X2B040U3PSBA is 40,000 BTU/h.

The digit after U or D later in the number (U3, U4, D5) is the blower size in tons. It is not heating capacity.

Trane’s product data for the S9X2, S9V2, S9X1 and S8 furnaces lists the input of every model, and it equals the three digits times 1,000. On two-stage models the code is the high-stage input. Checked on October 5, 2026: 174 of 174 models in the DOE certification database read to the certified size.

Checked against certified ratings

Trane L8 and L9 furnaces and American Standard AU and AD furnaces

Characters 6 to 8, after the cabinet-width letter.

L8V1seriesAwidth060inputU3VS***
Example: model L8V1A060U3VS*** reads as 60,000 BTU/h input. The DOE certification database lists it at 60,000 BTU/h of input.
AUHMseriesBwidth060inputCCV3V**H
Example: model AUHMB060CCV3V**-H reads as 60,000 BTU/h input. The DOE certification database lists it at 60,000 BTU/h of input.

These numbers copy the layout of the documented Trane furnaces. No document for them was found, so the layout was checked against the input each model is certified at. Checked on October 5, 2026: 20 of 20 models in the DOE certification database read to the certified size.

Is the size in the model number the exact capacity?

No. The code is the nominal size, the round number the unit is sold as. The capacity an air conditioner or heat pump is certified at depends on the indoor coil or air handler it is matched with, and it is usually a little below the nominal figure.

For example, the DOE certification database lists the Trane 5TTR3036A1 at 29,000 to 36,000 BTU/h of cooling across the indoor units it is certified with. Its size code is 36: 3 tons, or 36,000 BTU/h nominal.

The size of the unit you have is also not proof of the size the house needs. To check it, use the AC tonnage calculator or the furnace size calculator.

Where is the model number on the unit?

The model number is on the rating plate, next to the serial number.

On an air conditioner or heat pump the serial label is on the top right of the back of the outdoor unit. On a packaged unit it is on the rear panel.

On a furnace the label is on the right or left side panel. On an air handler or an indoor coil it is on the front panel.

Model numbers this page does not read

  • Cold-climate heat pumps (Trane 5TCV0X, American Standard 5A5V0X): the code is the nominal size in the catalog, but the certified cooling capacity is far below it. The DOE database lists the 5TCV0X36 at 26,200 BTU/h and the 5TCV0X48 at 36,000, so the decoder leaves them alone.
  • Ductless units (4TXK and 4TXM), evaporator coils (4TXC, 4PXC) and air handlers (TEM, GAM): their size codes sit elsewhere.
  • Older Trane numbers that do not start with 4 or 5, such as R-22 era units: not checked.

When a model number does not match a layout, the decoder says so. It does not guess.

How old is the unit?

The serial number on the same plate holds the build date: Trane serial number decoder, American Standard serial number decoder.

Questions and answers

How do I tell the tonnage of a Trane unit from the model number?

Read characters 7 and 8 of the model number on the outdoor unit and divide by 12. In 4TTR4036 the size is 36: 36,000 BTU/h, 3 tons. Sizes run from 18 (1.5 tons) to 60 (5 tons).

What does the tonnage listed for a Trane furnace mean?

It is the blower size: the largest air conditioner the furnace blower can serve. It is not the heating capacity. The heating input is the three-digit number after the cabinet-width letter.

Do American Standard model numbers work the same way?

Yes. American Standard is built by Trane. Its outdoor units start with 4A or 5A and carry the size at characters 7 and 8, the same positions as Trane.

Sources

Layouts last checked against these sources on October 5, 2026. Found a model number that reads wrong? Send a correction. How layouts are verified: method and sources.