How to Find Tonnage Size & SEER from Trane Model Number

You can find the Trane tonnage and SEER in the 5th, 7th and 8th characters of the Trane model number. The 5th character represents SEER in a single number; the 7th and 8th characters, also numbers, show the tonnage code.

The Trane model number nomenclature for central air conditioners and heat pumps is explained below in this Trane model lookup.

Sample Trane Model Number Showing Tonnage and SEER

This explanation works for any Trane AC or heat pump, units measured in tons or tonnage for size/capacity and in SEER for cooling efficiency.

For this discussion, we chose the Trane XL16i central air conditioner. It is available in sizes from 2 to 5 tons. The model number we selected at random is the 4TTX6048J model.

Note: This is the Trane model number, not the Trane serial number, a different number that reveals the manufacturing date and other important information.

Where is the Trane model number listed? You’ll find it on the outside cabinet of the unit. It is usually on a metal tag or sticker that also includes the Trane serial number, volts, circuit capacity, fuse info and much more.

Trane model number

Trane Model Number Nomenclature

OK, here is the breakdown of the Trane model lookup for models from 10 to 19 SEER, which covers most Trane ACs and heat pumps currently in use.

Here is our sample Trane XL16i model number: 4TTX6048J

The model number tells us that this is a 16 SEER AC, and its size is 48,000 BTU or 4 tons.

Character 5 Represents SEER Rating

How can a single number represent SEER ratings over 10? Here’s how.

0 is 10 SEER

1 is 11 SEER

2 is 12 SEER, and so on, up to 9 = 19 SEER

Characters 7 and 8 Represent Tonnage (Size)

Did you know? Tonnage or tons can be represented in terms of BTUs too. And that’s what the Trane number does. One ton equals 12,000 BTU.

So, you’ll need to convert the number to tons.

  • 18 = 18,000 BTU = 1.5 tons
  • 24 = 24,000 BTU = 2.0 tons
  • 30 = 30,000 BTU = 2.5 tons
  • 36 = 36,000 BTU = 3.0 tons
  • 42 = 42,000 BTU = 3.5 tons
  • 48 = 48,000 BTU = 4.0 tons
  • 60 = 60,000 BTU = 5.0 tons

All characters and what they represent:

Character 1: This is the refrigerant type, and 4 stands for R410A refrigerant. If your unit is older, it might start with 2, which represents R22 refrigerant, which is no longer used in new ACs.

Character 2: Trane model numbers always have a T for Trane in the second position.

Character 3: The character here shows what type of component it is – a split system AC or heat pump will have a T, as our example does. Packaged units have a C in the third spot.

Character 4: This position shows the product type or family. X is used for split system ACs and heat pumps. Z is used for packaged heat pumps and Y indicates a packaged AC-only.

Character 5: Here is where you’ll find the SEER rating represented. Our example has a “6” in this space, and that stands for 16 SEER. Wait a minute! The Trane page says this unit is capable of 17 SEER efficiency! Well, here’s the explanation from Trane. This unit was originally a 16 SEER heat pump. But improvements to the design boosted efficiency by 1 SEER. So, the way to read this number is that the unit is “at least” 16 SEER, and it might be a little higher.

Character 6: This spot shows whether the fittings and connections are soldered or brazed.

Characters 7 and 8: This is the size, abbreviated for BTUs. Our example has 48 in spaces 7 and 8. This stands for 48,000 BTU, which is 4 tons.

Here are other sizes for this model. Can you determine their size?




They are, in order, 1.5, 2.0 and 3.0 tons.

Characters 9 and beyond: A Trane model number can be up to 15 characters long. Most are shorter. The 9th space and beyond includes information about modifications made to the series since it was first introduced, voltage, additional functionality of the unit and a parts ID code.

What about 20 SEER and higher?

Trane only makes one AC and one heat pump with a SEER rating of 20 or higher.

The honest answer is that we’re not sure right now about the SEER code, but here is what we think Trane is doing.

Since the minimum SEER for heat pumps and ACs is 14 SEER (as of January 1, 2023), the Trane code has changed.  

SEER rating is still indicated by the 5th position.

0 = 20, 1 = 21, 2 = 22, etc.

We haven’t confirmed it yet, but this seems to be what Trane is doing. 

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree from Lone Star College and EPA & R-410A Certifications.

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