What can you keep on an R-454B swap?

Since the switch to A2L refrigerants the honest answer is: it depends on three separate things, and your manufacturer has already published the rule for each of them. This site finds that rule, quotes it, and dates it.

The three questions on your quote

• Can my indoor coil stay? Usually not — but which document says so, and does your brand publish an exception?
• Can my copper line set be reused? Usually yes, with conditions. The conditions are the part that costs money when they are skipped.
• Does my furnace need a mitigation kit? One brand answers this directly. Most have not answered it at all.

Start from a model number

• The unit I already own 26 R-410A models, what replaces each one, and whether a like-for-like R-410A replacement is still an option.
• The unit I was quoted 20 R-454B models, each with what it replaces and what you can keep when you fit it.

Start from your brand

• American Standard American Standard has not published, in the bulletin read here, a rule about using an existing R-410A coil with an R-454B outdoor unit.
• 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.

The maintained tables

• Which indoor units ship with leak detection Every coil on the site, whether detection is factory-installed, and where the manufacturer has published nothing.

Understanding the transition

• Can You Replace Just the Outdoor AC Unit? Two different questions hide inside this one, and they have opposite answers. One is about what the law allows; the other is about what the manufacturer approves.
• Do You Need a New Furnace With R-454B? One brand answers this directly and most have not answered it at all. What Carrier actually says about your existing gas furnace, and why a blank from another brand is not a yes.
• Mismatched Coil and Condenser: What Is Actually Known The internet is full of confident numbers about mismatched systems. Here is the documented part: the manufacturer's rule, the certified combination, and where a repair becomes a new system.
• R-410A Coil With an R-454B Condenser: What Actually Happens The pairing people are quoted and then talked out of. What the manufacturer says about it, and what a coil that is not interchangeable actually means.
• R-454B vs R-410A: What Actually Changed What R-454B is made of, why the equipment changed rather than the refrigerant being poured into old systems, and which of the differences reach a homeowner.
• The R-410A Phase-Out, for People Who Just Own an Air Conditioner Which deadlines are real, which one was lifted, what you can still buy, and what none of it changes about your existing system. Six rules, each dated.
• What the EPA's 2026 Rule Changed, and What It Did Not The installation deadline for R-410A equipment was lifted in May 2026. That changes what an installer may fit — it does not change what a manufacturer approves as a system.

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.