Copper pipe connections for fridge / freezer / aircon

[ErikFinn]

I hope this thread will find the attention of pro fridge techs with advice regarding joining fridge/aircon copper pipes.

I have recently become intrigued by diy fridge / freezer / aircon repair and maintenance. At my location there are no legal requirements for doing this work and after some bad experiences with local "techs" the only way to get anything done properly is to do it myself. I'm not a licenced tech but I understand the principles of operation of these machines, and have now come to a point where the biggest barrier is accomplishing good quality copper pipe joints fit for high pressure pipes, ie I want to add service valves, change compressors, connect cold plates (old ones with no quick couplings), and so on..

Conventional wisdom says this kind of connections should be "brazed", meaning you purge the pipe with nitrogen in order to avoid oxydazation / contamination inside the pipe, and hard solder the joint with a relatively higher temperature flame torch using silver solder. But this requires quite a lot of equipment and work imho. I would prefer something easier.

Furthermore, it is my understanding that "soft soldering" (using lower temps and solder that melts at lower temps) is not suitable for fridge/aircon copper pipes as the joint would not withstand the high pressures once system is running? Can anyone confirm this? One might (or might not) be able to avoid the contamination inside the pipe by using lower temps without nitrogen in pipe, but if the joint is weak or leaking then what's the point? Am I correct?

Then I recently discovered these " grimp-on quick connect couplers" (or whatever they are called) made by companies such as Parker (Zoomlock) and Vulcan Lokring ( Lokring) and a few others.

https://m.youtube.com/?#/watch?v=enZ9YUL5uUw

https://m.youtube.com/?#/watch?v=58UdzpEo7Qc

But these systems don't appear suitable for someone wanting to make just a few connections in his boat.. I believe to get started one has to buy one of their starter kits with the tool, selection of couplers, locking fluid, etc, and the initial cost would be very high. Looks like these ones are more suitable for high volume professional continuous daily use by a tech.

So.. What's left?

I can only think of two more options, *the self piercing valves (for adding a service port) and the flared couplings.

https://www.amazon.com/Supco-BPV31-B.../dp/B00DM8J3MI

but I know Mr Kollmann does not recommend them as they may leak. Are there any good ones that would be ok?

The flared couplings: would these be ok to use in fridge/aircon copper connections? I know they are used in household water and gas pipes but those applications have much much lower pressures than fridge/aircon pipes. How about use in fridge/aircon apps? Can they handle the higher pressures?

https://www.copper.org/applications/..._8flrdjts.html

If flared connections are deemed suitable I reckon that would be best option out of the ones above.. Simple cheap easy.

What am I missing??

Any other recommended methods?

Please comment.

Thank you.

Ps I tried the search and google but not much I could find. I would really appreciate to hear from the CF Pros.

[ErikFinn]

bump.

[Sailmonkey]

Flared connections are completely suitable. Split systems from the factory come with flare connections.

As far as the worry of contamination from heat and silver solder........you're over thinking this. Virtually every connection on a boat that is soldered is done so without inertin g the system. Not ideal, but neither is the real world.


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[GordMay]

See ➥ https://www.copper.org/applications/..._8flrdjts.html

And ➥ http://www.g-w.com/pdf/sampchap/9781566379656_ch03.pdf

[jamhass]

Originally Posted by Sailmonkey

As far as the worry of contamination from heat and silver solder........you're over thinking this. Virtually every connection on a boat that is soldered is done so without inertin g the system.

What he said. My neighbor is an appliance repairman, and he silver solders refer lines all the time without inerting. Just use a MAPP gas torch, properly clean the surfaces and don't use too much solder.

Local boat refer guy detests all mechanical fittings in boat refers. Claims 90% of his service requests and callbacks are due to mechanical fittings leaking. On new installs, he cuts them out and solders.

[jamhass]

PS:

Use Cu refer tubing, NOT Cu pipe. Pipe is hard and can (and does) crack from flexing and vibration (as in a boat). Refer tubing in soft, can be easily routed and is far more tolerant.

[Sailmonkey]

Originally Posted by jamhass

PS:

Use Cu refer tubing, NOT Cu pipe. Pipe is hard and can (and does) crack from flexing and vibration (as in a boat). Refer tubing in soft, can be easily routed and is far more tolerant.

Ah.....that. Yes, use refer tubing, normal plumbing tubing is contaminated with oils from manufacture. Refrigeration tubing is clean.


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[model 10]

Originally Posted by jamhass

Local boat refer guy detests all mechanical fittings in boat refers. Claims 90% of his service requests and callbacks are due to mechanical fittings leaking. On new installs, he cuts them out and solders.

Yep, that is what our local refer guy does also.

[Sailmonkey]

Originally Posted by jamhass

What he said. My neighbor is an appliance repairman, and he silver solders refer lines all the time without inerting. Just use a MAPP gas torch, properly clean the surfaces and don't use too much solder.

Local boat refer guy detests all mechanical fittings in boat refers. Claims 90% of his service requests and callbacks are due to mechanical fittings leaking. On new installs, he cuts them out and solders.

What does he do with the service valve/flare connections directly on the condensing unit? While I also don't trust the flares, the thought of soldering in places where I've put some of these things makes me cringe.

[model 10]

Originally Posted by Sailmonkey

What does he do with the service valve/flare connections directly on the condensing unit? While I also don't trust the flares, the thought of soldering in places where I've put some of these things makes me cringe.

The local guy uses wet rags which work surprisingly well.

[ErikFinn]

Thanks for all the replies and information guys. I wonder if this is a case of a pro can do?
That an experienced brazer can do the process without nitrogen and with no oxydazation inside the copper pipe?
Where as if I would go try it as a greenhorn I would just contaminate the pipe and ruin my system.
Have a look at this video, that's what I'm afraid of:

https://m.youtube.com/watch?v=Qw4vxJCBlzk

[SV THIRD DAY]

Hola Erik...

First forget purging the system with nitrogen as you are soldering...it's going overboard. Technautics has been making marine refrigeration systems since 1968 and all of them were soldered together without the nitrogen purging during soldering and we just haven't had a real life problem. The video grossly exaggerates the black oxides on the outside of the joint. As a fair comparison test, he should have soldered a joint without the nitrogen purge and showed the inside of that joint. But it wouldn't have looked anything like the outside where the direct flame is actively melting the silver solder and burning away the agents and impurities of the silver solder material. We also use a high quality flux on the solder joints and that helps with the oxidation and makes it much easier to get a better fill of silver solder into the joint. As an FYI, we use 50:50 silver solder it's more expensive, but a leaky joint on a unit that ships to Southeast Asia cost even more to warranty!


Now if you don't want to solder...don't.
Just use flare or compression connections and those will serve you well. They are also a LOT cheaper than the self-sealing refrigeration couplings! A set of the Aeroquip fittings we use made by Parker (Male and Female) is $90. The reason we (and all other marine refrigeration companies) use them is the simplicity of the plug-n-play precharged installation for the client. It lets us bench test the system and have it fully charged rather than the client needing to hire a Refrigeration Tech, who charges at an hourly rate as if he was a Cardiac Surgeon.


Now as for the refrigeration techs that play the "The mechanical fittings always leak, so I cut them off" card. That just a way for them to up-charge on what should be an easy installation of a plug and play system. It's total BS. Remember I take service calls for a living 7 days a week and a leaky refrigeration coupling is pretty low on the list of things I deal with on a daily basis. It's also easy to find and fix if it did happen anyway. Sorry if that offends anyone...but that's my honest opinion. Now, can a self-sealing refrigeration fittings leak...sure they can, but it's also a piece of cake to test them at installation with some soapy bubbles and verify the absence of leaks. We have 20-30yr old systems with the self-sealing mechanical refrigeration couplings still in service with no leaks. If leaks worry you, then buy a few spare coupling o-rings and carry them aboard. But it's just crazy to cut the refrigeration couplings off and void the warranty of every manufacturer and make it almost impossible for the cruiser to later self-service his unit out in the middle of nowhere....ahhh...good grief Charlie Brown. I've had to help several clients salvage their systems after their "expert Tech" decided to play this game and screwed things up, so I'm sensitive to these type of Dock/Chat room rumors.

[ErikFinn]

Thanks Rich. I'm relieved to hear nitrogen is not demanded..

How about choosing the torch for brazing? Is there anything compact available out there? What gas to use? I reckon I should use silver solder? Someone mentioned MAPP, I'll google that now. But for use in a boat I'd like something of manageable size, not two 40 liter steel tanks..

[ErikFinn]

Something like this would be ok?

Bernzomatic TS4000KC Trigger Start Torch Kit-TS4000KC - The Home Depot

[ErikFinn]

Another thought about brazing: I have a fixed critical orifice system (like Rich would call it) with a thin rolled evaporator plate and no filter dryer.

I believe these cheaper systems without a filter are more prone to contamination during any tampering with the closed system than Rich's top of the line Coolblue with a big filter.

Could I add a filter dryer to my system? Or to any similar system for that matter? If yes, where exactly should it go?

(should pull long vacuum and fill gas to about 95 to 100% plate frost after I reckon)