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Corrosion on heating pex fittings

I've got an 800 sqft room over an insulated garage floor.  I took off a cover to the rad to check the temp on the supply connection and found this. I went around and checked the rest of the crimps and each one shows the same corrosion.  I checked it with a gauge, and it was crimped correctly. 

I've got two theories:  The pex was not installed with respect to expansion/contraction and is moving around too much and water is squeezing past.  Another theory is the cold air vs warm air is passing through the unsealed holes and its a good spot for water vapor to condense. 

The original installation was around 2001. 


  • bob eck
    bob eck Member Posts: 925

    was that caused by flux when the fittings was soldered onto the copper baseboard element?
  • bob eck
    bob eck Member Posts: 925

    was that caused by flux when the fittings was soldered onto the copper baseboard element?
  • hot_rod
    hot_rod Member Posts: 14,785
    Glycol or water?

    did you check the ph of the fluid? Is it barrier or non barrier pex?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Danny Scully
    Danny Scully Member Posts: 1,325

    That really looks like the solder paste wasn't cleaned off the fitting after it was soldered. Try wiping it off with a wet rag then shinning it up with some grit cloth or a scotch bright pad.
  • shoudabeenaplumba
    shoudabeenaplumba Member Posts: 74
    I'll try cleaning it

    But the corrosion isn't near the solder joint but down where the elbow crimps to the pex.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    edited July 2010

    That is water leakage.

    There is sapposed to be a small collar of PEX above the crimp ring.

    That joint is not per factory design.

    I don't use crimp rings on PEX for heating - I believe Wirsbo compression bands are the only ones rated for heating. Domestic hot water crimp rings are not approved for space heating temps. ( unless something has changed since last year.)

    I use ROTH compression fittings.
  • shoudabeenaplumba
    shoudabeenaplumba Member Posts: 74
    Already started ripping it out

    And if anyone was curious that is NOT  barrier pex, but vanguard potable water pex.  4 lines run from the basement, all the same.  I'm scared but excited at the same time to see what I'm going to find.  Goes to show that even inspected work is not always perfect.
  • bob eck
    bob eck Member Posts: 925

    vanguard is now owned by VIEGA. Take a look at using VIEGA fostapex tubing. pex tubing with aluminum liner for oxygen barrier. their fittings and crimp sleeve are approved for heating and potable water systems. comes in 1/2", 3/4" and 1" sizes and comes in 150' rolls and 20' lengths. great product!! when running from a boiler with 180*F to baseboard, radiators, duct coils ect this product does not grow in length (like regular pex tubing does) or droop when the hot 180*F water temp runs through it.
  • kcopp
    kcopp Member Posts: 3,717
    I'd put...

    money on it is/was bad glycol.
  • MikeG
    MikeG Member Posts: 162
    Approved fittings

    Are we saying that all the major manufacturers do not approve their pipe for use with copper crimp rings for a heating application?  Is this a gray area, not a specific yes or no. 
This discussion has been closed.


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