How to know how much to tighten QS-20 fittings?

David_24

I'm connecting my baseboard radiation to the main panel with Wirsbo Multicor Pex-Al-Pex type tubing, using the QS-20 type brass compression fittings. The backside ring of the insert obviously compresses down onto the tubing as the fitting is tightened. The question is - how do you know when it is tight enough? After initial resistance was felt while screwing it on, I went about a turn and a half further but I know it could easily be turned more. Is there a rule of thumb on this - such as tighten as much as possible with a 6" wrench or the like? Thanks - Dave.

Al Corelli

If that is the correct fitting for the PAP, then tighten it until it doesnt leak.

Seriously, the fittings are made very well, and shuld not need to be cranked down too tight.

Make it snug. If it leaks, tighten it up some more.

The other choice is: One half turn before it breaks!

hr

Two grunts

is my motto

I doubt you could overtighten it with a 6" wrench. What type of 6" wrench do you have that opens that wide?

hot rod

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David_24

Very funny

to both Al and Hot Rod. I especially chuckled on the comment of "1/2 turn before it breaks". And hot rod, I guess I meant a 6" grab on a 12" wrench. Seriously - I just don't know if tightening till I can't turn it anymore would actually be too much crimp and cut the tubing or such. Thought maybe an answer like "2 turns past initial resistance" or some such might help to know. I am planning on doing the air pressure thing before filling, so maybe I'll know soon enough. Thanks for the responses - and any additional comments on the subject would be appreciated. Dave

Jim Franklin_2

pex insulation?

I'm still on the fence between copper & pex for my new system and had a thought- do the pex home runs get insulated? If so, with what? I did a quick online search for R value but found nothing.

jim

Gary Hayden_2

hr

The first thing

that usually happens, with any compression nut, is you split the brass nut way before you would damage the pex or PAP. My 10" Snap On brand cresent wrench just fits these nuts and does not have enough leverage to damage either the nut or tube.

Usually you will hear the brass start groaning or creaking when you are tight enough. Or the tube will start to rotate with the nut as it gets over tightened. Really!

hot rod

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David_24

Thanks again

Hot Rod....appreciate it. I know you guys are serious pros, and some of these "no brainer" to you questions are big questions for the DIYourselfer like me. So your last comment helped a LOT.... I'll probably give them all an extra twist, but I'll choke-up on that wrench initially until I do the pressure test with air... Thanks again....

David_24

Amateur response...

Jim... I'm not a pro - just an owner-builder that tries to pay attention. I used 5/8" Pex-Al-Pex to hook-up the baseboards. It might be a little more up-front cost, but there are advantages... One is, it can be easily run through joists. It is also a lot faster. And since there in very little mass in the pipe compared to copper, the water arrives hotter. Insulation - if the pipe is inside the living space, no need to insulate - the heat loss adds to the radiation. If in a unheated space, then just regular pipe insulation (foam) will do the job. Run it close to the floor above other insulation, and any loss will add to the room..

Dave