Some people online say you should wait after using cold-expansion fittings before adding pressure to the system. With Uponor pipe, is there any guideline on this?

  • You posted a link to their documentation a couple of days ago, is there anything in there?
    – FreeMan
    Feb 17, 2023 at 15:07
  • @FreeMan nothing whatsoever that I saw. But I found many random people on the internet saying you should wait 20 minutes to pressurize the system and if a leak occurs, even if later fixed, you should cut the fitting off and affix it again. Feb 17, 2023 at 15:32

1 Answer 1


In the absence of any directive from the instructions, if conventional wisdom says to wait 20 minutes, then that seems reasonable.

Unless you're making a repair, 99% of your fittings will have had a 20+ minute "rest" prior to pressurizing the water supply system. The only likely exceptions would be the last couple of fittings being crimped.

If this is new work, those fittings will likely have a day or more while you're waiting for the inspection, and the finish fittings probably won't be done for days.

If this is replumbing or repair work, that 20 minute wait can easily be absorbed by cleaning up messes & putting tools away.

If the wait is only 20 minutes, it seems that the time between making up the last fitting and actually turning water on will make it rather a moot point in any case.

I'd plan on waiting, just to be safe. Or, if you're into experimenting, make up a connection to a valve, close the valve, hold it over a bucket (just in case) and turn the water on right away, just to see what happens.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.