Tool/cable for testing refrigerant lines for crushing (not leaks)

Question

I have a flat in a new building and I want to install AC. The construction company has already installed the lineset for a multisplit system. These are brick walls, covered with plaster and finished with paint.

When the AC technicians came, they did a test for leaks and a test for crushed lines. For the crushing, they had some kind of very flexible cables with different diameters. They stuck a cable in the line, and if they couldn't push it through, they tried a smaller diameter.

Their verdict was that the line is fine in one room, but improperly installed in the second room. They told me they need to break up the wall, replace some length of the refrigerant line, then I have to have the wall repaired (which will likely show up, since the wall is already finished) and then I can call them again to mount the AC.

I called the construction company and they will be sending somebody to check the problem. I would like them to replace the line and refinish the wall free of charge. The AC technicians warned me that they encounter this problem frequently, and the construction companies tend to deny there is a problem. Apparently, they usually test by having somebody blow air through the line, and declare it good enough. The AC people warned me that the reduced pipe diameter will be a problem for the AC running properly, and said that their company won't install an AC on crushed pipes.

So my plan is now to be able to demonstrate to the construction company person the problem with the pipe. Ideally, I'd get the same tool (cable?) and have it handy so the problem is obvious.

My question is: what is this tool? I don't want to purchase some random cable, which may be the wrong diameter, or not bendy enough. I suppose it's not purpose-built for AC testing, but I don't know what it's called and what's the original purpose, so I don't know what to look for, and where to go to search for it (hardware store, electricians', somewhere else)? My best description is that it looked like a small-diameter rubber tube, but I suppose it must have been solid inside, so it won't get squished itself when encountering the crushed place in the pipe. At the same time, it was much more flexible than a copper (electric) cable with rubber insulation.

Answer 1

Conduit systems are sometimes proofed to verify that they maintain some minimum diameter to assure that a fiber optic or electrical cable of a known size will fit into the conduit appropriately. For testing my 14 mm ID microduct I use a simple 10 mm steel ball and blow it through the pipe with compressed air. When there's no kink in the line the ball can build quite a lot of speed accelerating through 40-80 m length of conduit so this has to be done with attention to catching the steel ball in a safe way (bend the pipe so it shoots into the soil, or catch in an appropriate wood or steel container, etc).

Air conditioner technicians sometimes will clean a refrigerant lineset with... a "lineset cleaning tool." It is just a foam plug sized to fit the tube. It can be blown through with compressed air to wipe clean the interior walls. One might expect that a plug for cleaning eg a 3/8" line set would jam at a severe kink/crush damage.

Are you certain that the tool used by your technicians was intended for the purpose? I wonder if they might have just used something like a set of fiberglass electrical fish tapes which just happened to be different sizes. This sounds like the kind of thing for which no formal tool exists; innovative trades people just find a solution using re-purposed parts and tools.

Answer 2

The construction company reacted surprisingly quickly, and today they came with their AC subcontractors to repair the damage.

The constructor's AC technicians told me that the testing tool is made of silicone - basically a single thick filament of many meters of silicone. I didn't ask where it can be bought, but if it's a repurposed tool mainly known under a different name, they didn't know about the name or original purpose. In fact, they didn't have a special name for it either, and called it "the long silicone thing".

To also report on what happened: they hadn't brought such a tool along, apparently their company doesn't do this kind of test commonly, unlike my chosen installation company. But they opened the wall, found the bent piece in the pipe and replced it. I had bought a very flexible fish tape made out of a super-long metal spring, and we inserted that into the repaired pipe. It went in freely. I don't think the nylon style fish tape would have worked well, and a certainly not a single-wire fish tape. The spring body of the fish tape would have been a bit thin, but the head happened to be a very good diameter for my copper pipe. That may be different for different homes, as apparently the linesets have different diameters depending on the AC unit's power, which gets calculated based on room volume.

Conclusion: very flexible fish tape works for that kind of problem quite well. If the pipe is a different diameter, one might have to somehow enlarge the fish tape's head (wrap tape around?). The actual tool seems to be AC-tech-specific, but I couldn't find out a name.