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3/8" OD copper to 1/2" ID primochill

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Meathead

Member
Joined
Jul 14, 2004
Location
westminster, CO
I'm looking for some type of fitting to go from 3/8" OD Copper to 1/2" ID primochill tubing as the title says. Currently, I have a 3/8" OD compression coupling with female threads and then screw in a male thread to 1/2" barb. It is currently very slowly leaking from both the compression fitting and the thread connection after I tightened them with 2 crescent wrenches. I think I can fix the threaded part with using a bit more of the white plumbers tape but I'm not sure how to make a better connection with these compression fittings.

Can anyone think of a better approach? I can't find a 1/4" sweat to 1/2" barb (PEX) connector anywhere so my next idea was to get a 1/4" to 1/2" copper to copper adapter fitting and then run a small piece of 1/2" copper to a 1/2" sweat to 1/2" barb. That seems like a pain in the rear end but the only way I'm going to get a higher rated PSI connection than compression.
 

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Witchdoctor

Member
Joined
Apr 12, 2014
Disasembel re tape threads and tighen them, then pull the compresion nut back, wrap some tape around the ring and retighten
 
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Meathead

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Joined
Jul 14, 2004
Location
westminster, CO
or just go with a 3/8 to 1/2 OD copper bell reducer and a length of 1/2 OB copper, then put the tubing ends in hot water and slide (force) it over the copper pipe 2-3" should do. Secure with jubilee clips.

http://www.plumbingsupply.com/copper.html

Hmm I like the creativity of that idea but if I were to already have to get 1/2" pipe and solder it, I might as well solder a male barb on there so I am using the fittings as designed.
 
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Meathead

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Jul 14, 2004
Location
westminster, CO
Disasembel re tape threads and tighen them, then pull the compresion nut back, wrap some tape around the ring and retighten

Hmm I used more tape and the threads worked but how exactly do you tape around the ring? Is it the ring or do you put that white tape around the actual copper pipe.
 

Witchdoctor

Member
Joined
Apr 12, 2014
When you pull the compression nut back the ring should be exposed, simply wrap the tape around the ring and pipe, them slide the nut back down and tighten, you do not need much, this will work unless your fitting has the wonky kind of rigs that are connected to the nut it self.


skip to 1:50 and simply wrap the tape around the nut once it has the proper set back

 
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Meathead

Member
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Jul 14, 2004
Location
westminster, CO
When you pull the compression nut back the ring should be exposed, simply wrap the tape around the ring and pipe, them slide the nut back down and tighten, you do not need much, this will work unless your fitting has the wonky kind of rigs that are connected to the nut it self.


skip to 1:50 and simply wrap the tape around the nut once it has the proper set back


Crap thats why I was confused. I do indeed have a wonky connector attached to the nut as you described. I think I'm going to quit wasting time and just do sweat all the way to barb. If you solder correctly, these bonds are insanely strong.

Thanks for your help. Last time I buy fittings from homedepot. They always have weird parts that SUCK.
 

NiHaoMike

dBa Member
Joined
Mar 1, 2013
Compression fittings, especially on copper, are infamous for being quite hard to get a leak free connection. I recommend flare fittings. The main downside is that you'll need a flaring tool (and you must remember to put on the flare nut *before* putting on the tool), but it's dependable enough to be widely used in the HVAC industry.
 
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Meathead

Member
Joined
Jul 14, 2004
Location
westminster, CO
Compression fittings, especially on copper, are infamous for being quite hard to get a leak free connection. I recommend flare fittings. The main downside is that you'll need a flaring tool (and you must remember to put on the flare nut *before* putting on the tool), but it's dependable enough to be widely used in the HVAC industry.

Interesting. Thanks for the info. I'll have to check it out.
 

Robert17

Premium Member
Joined
Feb 1, 2011
Location
Republic of Texas
Compression fittings, especially on copper, are infamous for being quite hard to get a leak free connection. I recommend flare fittings. The main downside is that you'll need a flaring tool (and you must remember to put on the flare nut *before* putting on the tool), but it's dependable enough to be widely used in the HVAC industry.

I've never had a leak using compression fittings so I don't understand your use of the term 'infamous'. And I've used them throughout the house replacing almost all my sweat fittings over time with compression. I also use a gooey thread sealant instead of tape; it's easier to apply, never hardens, is potable-friendly, and one can of it stores for years, 15 years in my garage or example.

I haven't used my flaring set for years now although I grant that flaring is very effective as well. But preventing leaks using flared fittings was a bigger challenge for me for whatever reason. The latest, PEX fittings, and slightly older DOT push-in fittings work quite well too. Don't be 'askeerd' of trying something different. The technology is widely used in many industries and quite effectively.
 

NiHaoMike

dBa Member
Joined
Mar 1, 2013
There's some trick to getting the brass ring to seal around the copper. In particular, applying a force to the tube tends to cause it to leak. On PEX, compression does work quite well.

If your flares are leaking, you probably haven't made them right and/or applied the wrong amount of torque. There's a good reason why flares are very commonly used in HVAC and compression isn't.
 
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Meathead

Member
Joined
Jul 14, 2004
Location
westminster, CO
I've never had a leak using compression fittings so I don't understand your use of the term 'infamous'. And I've used them throughout the house replacing almost all my sweat fittings over time with compression. I also use a gooey thread sealant instead of tape; it's easier to apply, never hardens, is potable-friendly, and one can of it stores for years, 15 years in my garage or example.

I haven't used my flaring set for years now although I grant that flaring is very effective as well. But preventing leaks using flared fittings was a bigger challenge for me for whatever reason. The latest, PEX fittings, and slightly older DOT push-in fittings work quite well too. Don't be 'askeerd' of trying something different. The technology is widely used in many industries and quite effectively.


Compression fittings are known for being the least reliable connection. I mean just look at it. It looks pathetic compared to solder or barb with hose clamp. I think that's what he was getting at.

And I would never change pipes in your house, ESPECIALLY if they are behind drywall aka no exposed, to compression. That's just asking for trouble.
 

RnRollie

Member
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Oct 10, 2012
Location
Secret lair
Compression fittings are known for being the least reliable connection. I mean just look at it. It looks pathetic compared to solder or barb with hose clamp. I think that's what he was getting at.

And I would never change pipes in your house, ESPECIALLY if they are behind drywall aka no exposed, to compression. That's just asking for trouble.

True

Then again, nowadays full copper (or stainless) piping is becoming rare, its doublewalled re-inforced pex almost all the way now, especially in drywall
 
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Robert17

Premium Member
Joined
Feb 1, 2011
Location
Republic of Texas
Compression fittings are known for being the least reliable connection. I mean just look at it. It looks pathetic compared to solder or barb with hose clamp. I think that's what he was getting at.

And I would never change pipes in your house, ESPECIALLY if they are behind drywall aka no exposed, to compression. That's just asking for trouble.

I'm not sure of your meaning. I don't 'change pipes' using fittings. In fact I added some length to a shower run several years ago which was behind some drywall and brazed the coupling. No issues. Least reliable? I've had sweat fittings corrode and had a difficult time rebrazing so simply melted the solder with a torch and replaced the valve with a compression fitting; no issues in a dozen years. Looks pathetic? What do looks have to do with effectiveness?

And I've seen steel clamps on hose fail due to corrosion. I'm pretty sure any clamp can fail over time, especially if not properly selected and installed.
 
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Meathead

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Jul 14, 2004
Location
westminster, CO
I'm not sure of your meaning. I don't 'change pipes' using fittings. In fact I added some length to a shower run several years ago which was behind some drywall and brazed the coupling. No issues. Least reliable? I've had sweat fittings corrode and had a difficult time rebrazing so simply melted the solder with a torch and replaced the valve with a compression fitting; no issues in a dozen years. Looks pathetic? What do looks have to do with effectiveness?

And I've seen steel clamps on hose fail due to corrosion. I'm pretty sure any clamp can fail over time, especially if not properly selected and installed.


Sorry I meant pipe fittings. And it looks pathetic in the robust department. Looks can matter. When I first started getting into water-cooling, I remember looking at a compression fitting for the first time and instantly knowing that even if I was able to perfectly seal a connection, that it would be susceptible leaks from any movement or vibrations or just be a pain in the *** in general to use. That's exactly how they are.

You can just look and feel a well done soldered joint or hoseclamp connection and it seems like a good choice if you want reliability. I've also never had soldered joint or hoseclamp leak yet I've had every compression fitting I've tried leak until I tweak it just right. As always, YMMV. I'm not saying that soldering or hose clamps are invincible but when done right are all around generally extremely better for most purposes.
 
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NiHaoMike

dBa Member
Joined
Mar 1, 2013
There's a better sort of compression fitting known as a Swagelok that uses a 2 piece seal. It is sometimes used in HVAC but nowhere as much as flare fittings.

The quality of the metal used in the seal apparently matters a lot. If it's too soft, it won't "bite" into the copper and seal properly, but would work perfectly fine with PEX as PEX is very soft compared to copper.