Mini-split line brazing - I question this method

hcoles · 09-09-2023, 06:13 AM

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.

unclebilly · unclebilly's Garage

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.

gsxrken · gsxrken's Garage

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

hcoles · 09-09-2023, 06:54 AM

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.

unclebilly · unclebilly's Garage

Quote:

Originally Posted by gsxrken

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. … Ugh

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?

Paul T · 09-09-2023, 07:06 AM

Quote:

Originally Posted by gsxrken

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

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.

pavulon · 09-09-2023, 07:07 AM

That's BS workmanship. You should be pissed.

Bob Kontak · Bob Kontak's Garage

I'm with unclebilly.

What do you want strength or beauty?

Baz · Baz's Garage

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

hcoles · 09-09-2023, 07:54 AM

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.

908/930 · 908/930's Garage

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.

hcoles · 09-09-2023, 09:44 AM

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

billybek · billybek's Garage

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.

oldE · 09-09-2023, 09:57 AM

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

carambola · carambola's Garage

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

Bill Douglas · 09-09-2023, 11:46 AM

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.

sc_rufctr · 09-09-2023, 11:54 AM

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.

peppy · 09-09-2023, 12:40 PM

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.

look 171 · 09-09-2023, 01:12 PM

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

Brian 162 · 05:27 PM

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