Questions about using a Watt's compression fitting with Pex

[Lee_Leses]

I picked up some 1/2" Watt's compression unions that I may use to join 1/2" copper to 1/2" pex. I wanted to see if anyone has used this method to know if it produces a strong enough joint that will not have problems later. The Watt's fitting looks like the ferrule is built right into it now, the ferrule is not a separate part like I'm used to. And Watt's gives you an insert to put on soft plastic tubing.

I want to assume that you do NOT use the insert with the Pex, because the Pex is hard enough that you don't need it. I tried to push the brass insert into a piece of Pex tube, and that does not seem like it is meant to go into Pex, I think the insert is meant for softer tubing?

It's a Watts LFA210 PB962 P 1/2

Also, how careful do you have to be not to crack the Pex or compres it too much? Ferrules onto copper pipe make sense to me and when done correctly with a half turn after they seem tight, they will seal well. I'm more skeptical about a compression fitting on Pex or other plastic tubing, so I wanted to ask if it works well, especially long-term. Do you do about a half turn after it feels tight, just like you would with copper?

I'm also thinking I like the idea of a Watt's compression fitting to make the transition from 1/2" copper to 1/2" pex more than a press on Sharkbite. Any thoughts on that? I think the Watt's fitting would last longer, in the long run. If things go well, I will sweat a copper to pex adapter onto the copper pipes. These fittings are my backup for if things don't go well... LOL!

THANK YOU!

Lee

 

[hj]

If you can ALWAYS keep a compression joint from leaking by just turning it a half turn past "tight", you have been lucky. WIthout the insert, ANY plastic line can compress without creating a tight connection.

 

[Sponsor]

 

[Jadnashua]

Pex does require the reinforcement inside. Pex isn't always perfectly round, so the round insert may be tough to put in. Sometimes a heat gun or a cup of really hot water will soften it enough to make it easier.

 

[Lee_Leses]

HJ - I don't do this all the time so I've just been lucky I guess!

jadnashua - Do you use the insert supplied with the Watt's fitting? You don't need any kind of special insert because it's pex, do you? Just checking!

 

[Cacher_Chick]

I've never considered a compression fitting for PEX since a standard sweat PEX adapter is readily available and unquestionably reliable.

 

[Lee_Leses]

Yes, the sweat adapter is plan A.

This crawlspace is so nasty, I wanted to have a plan B in case I run into any problems in the hole. Like if I can't get the pipe to drain right to solder or something.

I want to get in and get out ASAP.

LOL!

 

[Jadnashua]

Pex will collapse and leak or come off with decent pressure if it is not squeezed between the compression and the insert.