American Standard: what you can keep on an A2L swap
Checked against Refrigerant Transition Changes: Air Handlers, Coils, Air Conditioners, and Heat Pumps, September 2026.
American Standard puts the refrigerant detection where Carrier does not: in the coil, on every coil, with a wire harness running from it to the furnace that an installer has to connect in the field. That single sentence in its transition bulletin changes what a homeowner should expect to see on the quote, and it is the clearest example on this site of two manufacturers answering the same A2L question differently. The bulletin covers American Standard Heating and Air Conditioning and Ameristar by American Standard together. Its two heat pump families are on this site; the three Silver air conditioner families and the air handlers in the same document have not been transcribed yet, so this brand is incomplete and says so.
Indoor coil
Not publishedAmerican Standard has not published, in the bulletin read here, a rule about using an existing R-410A coil with an R-454B outdoor unit.
What the bulletin does say is that the R-454B coils are a new product family with new model numbers, that every one of them carries a refrigerant detection system, and that the R-454B outdoor units have new TXV and refrigeration designs optimised for the new refrigerant. None of that is the same sentence as "an R-410A coil may not be used", so this site does not write that sentence on American Standard's behalf. Ask your installer to show you the American Standard document that answers it.
Line set
Not publishedWhether your existing copper can be reused is not answered by this bulletin — and it names something that makes the question sharper.
The bulletin states that the R-454B single-stage heat pumps have new service valve connection sizes. That is a change at the point where your line set attaches to the outdoor unit, so "can the copper be reused" and "will it connect the way it did before" are two questions here, not one. Neither is answered in this document.
Furnace
Can stay, with conditionsYour furnace is not replaced, but it does not come away untouched: a new factory-supplied wire harness runs from the detection system in the coil to the furnace and has to be connected in the field.
- The new wire harness between the coil's refrigerant detection system and the furnace is connected on site — American Standard supplies it, the installer has to land it.
- Your furnace has to be one the harness can be connected to. The bulletin does not list which furnaces those are.
What to ask your installer about any American Standard swap
- Does the manufacturer publish a document approving my existing coil with this unit? Can I see it?
- Which mitigation kit does my furnace need, and is it in the quote?
The documents behind this
ManufacturerA Refrigerant Detection System is added to the coil product family. It contains a leak detection sensor and a mitigation control board mounted to the coil, and a new factory-supplied wire harness runs between the system in the coil and the furnace, requiring field connection.
ManufacturerR-454B coil model numbers change in the 1st, 9th and 14th digits, and some models also change in the 6th, 7th and 8th.
Our readingBecause the changed digits sit at the start, the middle and the end of a fourteen-character number, a coil number that looks almost identical to yours can be for the other refrigerant. Read it character by character.
ManufacturerOutdoor products carry a 5 in the first digit of the model number to identify the new refrigerant, where the R-410A equivalent carried a 4.
Our readingThe bulletin's own heat pump table shows one family where that is not how it reads: the Ameristar A4HP5 becomes the A5HP5, so the 5 is the second character and the first stays an A. Someone checking only the first digit of that model would conclude their unit is not in the table.
ManufacturerThe single-stage R-454B heat pumps have new compressors, new service valve connection sizes, and new TXV and refrigeration designs optimised for the new refrigerant.
ManufacturerThe bulletin covers American Standard Heating and Air Conditioning and Ameristar by American Standard together, and says it will be updated as more R-454B products are released.
What replaces what: the American Standard A2L range
Every American Standard A2L outdoor unit on this site, and the R-410A model it replaces. This is the table that today exists only inside a PDF. The last column says which document each row was read from; a model links to its own page once a document about that model has been read.
| A2L model | Type | Tier | Compressor | Region | Replaces | Data read |
|---|---|---|---|---|---|---|
| 5A6H4 | Heat pump | Silver 14 Heat Pump | single-stage | — | 4A6H4 | service bulletin only |
| 5A6H5 | Heat pump | Silver 15 | single-stage | — | 4A6H5 | service bulletin only |
This is a starting point, not an approval. Everything here is read from published manufacturer documents and dated, but only the licensed contractor who signs your installation can approve a specific system for your home and your local code. Take the citations on this page to them and ask.