Swap rules by brand
Every brand answers the three questions differently, and some do not answer them at all. This table is the comparison; each brand page below it is the document, the quote and the date.
The three answers, side by side
| Brand | Indoor coil | Line set | Furnace | Models | Read from |
|---|---|---|---|---|---|
| American Standard | Must be replaced | With conditions | With conditions | 10, 2 with a page | service bulletin only |
| Carrier | Must be replaced | With conditions | Can stay | 42, 16 with a page | brand FAQ, install manual only |
What "not published" means here
It does not mean the answer is no, and it does not mean the answer is yes. It means that in the documents read for this site, that manufacturer has not addressed the question — so this site says so instead of guessing, and gives you the question to put to your installer.
A blank is worth as much as an answer when you are holding a quote. An installer who says the coil can stay is making a claim their manufacturer has not put in writing, and that is a reasonable thing to ask them about before the old one comes off the wall.
What each brand says about your coil
- American Standard Your existing R-410A coil cannot stay. American Standard states it directly: an R-410A evaporator coil cannot be used or converted with R-454B, and the R-454B coil has to be factory equipped with a mitigation control board.
- Carrier Your existing R-410A indoor coil cannot stay. Carrier states that full furnace coils are not interchangeable and that the refrigerant the indoor coil is designed for must match the outdoor unit's.
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.