(The content of this post is intended for consideration by trained service personnel only)
Replacing reversing valves is one of the more taxing repairs to heat pumps. I’m sure every tech has his preferred method for doing it, which probably depends on his personal level of confidence, skills and dexterity with a torch. The primary objective (for me) is getting the new valve in, without destroying the internal heat sensitive components. The valve body can only withstand temperatures approaching 250 F degrees…which ain’t much considering the 1400 F or so necessary to get a good braze joint.
And you have to consider in most cases, the valve is in a position where you can’t just “sweat” it out. There has to be some “slack” available and usually isn’t. Even if you have the special torch attachment that can heat all three tubing connections simultaneously, you still need room to pull the valve away from the tubing. Even if you manage that, you got to consider brazing in the new one without burning it up.
So, I usually study the “geometry” of the valve and try to cut the tubing in places I can easily access on the re-braze…Then, once you get the “assembly” out, you can heat the connections in whatever manner you prefer and remove the old valve.
Then, you only have to braze in the new valve one tube at a time, allowing you to use wet rags or whatever, to keep the valve body cool.
Once you complete that step, using swaged ends or couplings allows you to reconnect the cut joints.