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brettmarl
Heating PEX Copper Stubs

I had a plumber run some new pex supplies for a sink in my basement. The pex stubs into 1/2" copper for the rough-ins as normal.

The supply faucet I want to put on the copper is NPT threaded vs. a compression fitting, so my plan was to cut the stubs to length and solder a threaded copper fitting on the end.

Is it OK to heat up those short sections of copper with PEX attached an inch or two behind it? I'm nervous that I might compromise the connection.

Fencepost
Re: Heating PEX Copper Stubs

You'll find it a lot easier to just buy some stops that have compression fittings on the inlet -- 1/2" copper is 5/8" outside diameter.

Chances are the copper stub has a 90-degree bend just inside the wall, so there's probably about 8" from where it enters the wall to where it meets the PEX. PEX can withstand quite a bit of heat, so long as there's no stress on the pipe while it's hot.

(When I was an apprentice plumber, I learned that for a certain brand of PEX, if it was kinked, you could restore it to full strength by heating it until it turned clear, straighten it out, then let it cool. This method is approved by the manufacturer when performed by a certified installer. I can't say that you won't void any warranties or cause a flood; I tell you that for your information.)

brettmarl
Re: Heating PEX Copper Stubs

fencepost,

thanks. the copper stubs are tied into a plate, so there shouldn't be any stress caused. here's a photo of the rough-in before drywall:

yeah - compression would be easier. but it's an aestetic issue as it's going to be an open wall-hung sink with the fittings very visible - so we're using some fancy shut-offs that unfortunatley are threaded.

sounds like i'm all clear to fire up the blow torch :)

cheers,
-brett

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