Mini-split line brazing - I question this method
 

I'm upset. A company, supposed to be one of the best, is installing a mini-split system in my house. See picture. I can't believe this method of connecting two diameters is considered approved or a best practice. It looks like he pinched the larger line so that a braze joint could be attempted. I think a quality flare joint is preferred at this connection point. If someone says it is done all the time, that is really not a good answer.
AC technicians please comment.
Thanks.

http://forums.pelicanparts.com/uploa...1694268495.jpg

The solder that wicks into the annulus between the tubes is what gives the seal, not the ugly part you see. If the overlap is an inch or so,it will be fine. Better than any flare.

Disagree. That’s a poor job. He should either used a reducing adapter or an expansion tool to step / stretch the one line to fit over the other.
And dollars to donuts: the guy that was ok with that method did not back purge with nitrogen, so you’ll have all sorts of carbon particulate circulating forever in your system. Ugh

Yes, that's exactly what I'm thinking. Should have used an expansion tool or reducer. Also, I'm having a hard time envisioning how nitrogen can be flowing very well if it has to flow through the outside unit pump/etc. The nitrogen is supposed to be FLOWING.

So you are saying this won’t work?

You’ve calculated the shear strength of the solder in the annulus, the shear strength of the solder bonds and drawn this conclusion or just an opinion?

The reducers make it easy but not necessarily better. Ever seen how a brass radiator is made?

I concur, workable or not that is just sloppy and lazy work. I’d be worried about the rest of the job. This is someone who has no pride in what they do, IMO.

That's BS workmanship. You should be pissed.

I'm with unclebilly.

What do you want strength or beauty?

http://forums.pelicanparts.com/uploa...1694273831.jpg

http://forums.pelicanparts.com/uploa...1694273854.jpg

Ha ha...I'm with Bob....:)

I am pissed. They are going to try and work today but my thinking now is to shut the job down until this gets resolved. To start with they said there would be very few if any brazed joints and now I have brazed joints all over the place. I watched as they flowed nitrogen and they cut it way down probably because one end wasn't open. I'll try to contact Mitsubishi on Monday.

The clearance between the two tubes should be about .002"-.005", looks like about .03" on the small tube. I am curious how much overlap he did.

Check the installation manual and see if they give a brazing spec? Good luck.

Update - They got some proper adapter fittings and are putting them in now. Unreal.

It is done.
It does look kind of crappy.
I agree that a swedge would have looked nicer but they are dissimilar in size.
It shouldn't affect performance and if the joint is filled with silphos solder, there shouldn't be any possibility of moisture getting into the joint and freezing. This can cause problems with outdoor piping over time.
A reducing fitting would look better and more professional.

I suspect if you took a peek at the back of your refrigerator or the reefer unit on most trucks, you would find identical joints. That joint isn't pretty, but it is unlikely to fail.

Best
Les

Looks like you had oversized lines installed.
I wonder what the difference is ...

I think it will work fine if it is brazing - not solder. Just a bit inelegant looking.

I do my own plumbing as a hobby and to save money, and I definitely would have used a reducing adaptor. And brazed it using silfos. As an amateur I tend to be extra tidy and over engineer everything to be on the safe side.

The joins are ugly for sure but if they're hidden and reliable does that matter?

It doesn't to me but if you can see those joints then it's worth fixing.

I see a lot of refrigeration work around the restaurant and it's pretty common joint.

I saw a man crimp down the inside line and make a temporary expansion valve. it worked fine until we could get the correct part.

I see it all the time, it is and will be fine. If you are looking for beauty, then go with someone else.

I've done it that way as a last resort when I couldn't swedge the fitting or have the correct reducer.
I have a toolbox filled with couplings elbows and reducing couplings.
It will probably work but in my opinion it looks like crap
I'm pretty ocd. If I had to see that every day I'd lose my mind

6 houses later and every one was done like that. It will last longer than your teeth.

I am curious why is any solder/brazing needed ? My Mitsubishi mini split in my man cave garage the copper line sets are attached via flare fittings . My previous Mitsubishi mini split at a different house was the same way . Have they changed the design ?

The flare connections are there but to the left - more inside.
I don't like more braze joints than necessary.
At this point I'm not too happy with the quality I'm getting.

^^^ So why aren't the copper lines one piece from the flare on the condenser to the flare on the evaporator ? I wouldn't be happy with your install either .

Because they brought the line set material on the first day and it was cut to length already without good checking on the dimensions needed. I just don't understand why they would do this after years and years of experience. I've worked with top quality workmanship from plumbers at the University of California. The quality comparison is dramatic. I'm guessing the pay comparison is also dramatic.
This is what I get for choosing one of the top companies around here for this sort of work.

Reminds me of the saying " I cut it 3 times and it's still short " 😩 . If that work is from one of the best I would hate to see lesser than work .

When I installed mine I hooked up all wires and copper lines to the inside unit . Then called the installer . He terminated everything at the outside unit . All to proper length and all to fit inside vinyl chase . To me that is the only way to do it .

I wish you well getting a clean and professional install . Good luck .

I had my radiator repaired at a big radiator place and the guy made it look effortless, result could have been in a museum.

That photo looks like some mess that I would make. Either they had the new guy do it or just no pride in their work.

If you're actually paying top dollar you might want to talk to their boss? The joint isn't a real problem but other shoddy work might be.

I rather have silver brazing for connection then flared nuts.

Again, it may not win any beauty contest, but it will work for a very long time. Plenty, I bet more then an inch of silver brazing materials in there to prevent any leaks. That if they didn't just shove it together with only 1/4" within the the larger diameter pipe

Sorry, but it's overheated even if that kind of joint is Kosher.

Well, here we are now. The system is "installed" and they are having difficulty hitting the evacuation numbers. One junior worker tried brow beating me into accepting evacuation and hold numbers that they were able to do, not following Mitsubishi spec. If anyone wants to discuss the Diamond Contractor "program" advertised by Mitsubishi I can do that. I'm not feeling it. I think it is just the state of the residential industry - do subpar work and get the customer to accept it. Of course there are professional excellent techs out there - I don't know how one finds them. I found so many mistakes at this point. Probably more I don't know of.

That's a leak!

Yup. That *****ty braze is the first place I’d look

The 600 psi pressure test.... sort of passed? It is hard to tell because the gauge reading goes up and down with temperature. Started at 600 and went to 592 over 12? hours. I have a graph.
At this point they need to be professional and get the guy that knows what he is doing to come on site. He is coming from Texas to CA. Longish story on that.
The "leak" is one or more of:
- instrumentation/vacuum hoses/fittings/etc.
- a "pool" of water somewhere in the line sets (haven't cracked the isolation valves)
- bad flare fitting
- bad braze joint
- could be the isolation valve(s) have a leak but this is described as unlikely

There are many classes and various videos regarding finding leaks and evacuation on YouTube. I find it interesting.

This is two weeks of install, I think that company needs to send some of their installers for some proper training. Did they try checking the welds with soap with the 600psi charge? There is spray on dye penetrant test that would likely find any holes but requires no internal pressure. Did they clean and flux the new fitting prior to brazing?

The one person that has the proper training is the general manager. He now remotely "manages" the California workers from his home in Texas. The company is required to have one officially trained person in order to advertise being Diamond level. I asked for the trained person and that "forced" them to fly the person out from Texas. I think he comes once a month anyway.
Re. soap. You are not supposed to use soap. They have non-corrosive bubble fluid now.
I was not able to watch re. how they did the brazing.

I’ve seen that type of brazed joint many times over the years. Usually on distributor lines from the txv to evap coil. O.K. when it’s out of sight, but that’s just sloppy unprofessional brazing. Should have used reducers or swedgedd the lines. Silfos is normally used for connections. Brazing is a learned technique. When I worked at Carrier, I went to brazing classes to learn the proper techniques for using 45% silver. Just unprofessional sloppy rushed job in my opinion. I do my own solder work anyway.

How did you know the company owner would say that to me?

What did you expect him to say ? Yeah we do this crap all the time what's the problem ? Nope . Your expectations of a professional install are valid . Their expectation of slamming it together and getting paid are not . Hopefully the 2nd time around they do a better job .

A new system should be able to hit 250 microns easily. 250 microns not rising over 500 in a 10-15 minute time period while the pump is isolated or blanked off from the circuit.
Moisture in a tight system will freeze and the vacuum level may get close to 500 microns or below but the ice will sublimate decreasing the vacuum level over the time period the pump is blanked off from the system.
What evacuation target was specified by the manufacturer?