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Thread: Pinholes in Hot Water Loop

  1. #1

    Default Pinholes in Hot Water Loop

    We had a new Weil-McLean boiler and hot water tank added five years ago as part of a re-modeling project. The gas boiler heats my hot water. The hot water is circulated to the faucets - this provides instant hot water. Starting last winter we have had four pinhole leaks in the hot water loop. Two of the holes are in the copper pipe that is only five years old. The circulator runs 24/7. I suspect there is a problem with this hot water loop. The water is supplied by the town - it is not from a homeowners well. There have not been any pinholes in the cold water pipes (most of the house has 55 year old copper pipes).
    Could the circulater pump be operating too fast?

  2. #2
    DIY Senior Member thezster's Avatar
    Join Date
    Jul 2005
    Fort Collins, Colorado


    Check the post down the page titled "Pinhole leaks"... it offers many suggestions as to this very problem..... Good Luck

  3. #3
    That's all folks! Gary Slusser's Avatar
    Join Date
    Aug 2004
    Wherever I park the motorhome.


    Yes the velocity could be too high and resulting in erosion corrosion. Usually a few inches from fittings. Another cause is excessive flux or nonwater soluble flux or, not reaming the ends of pipe when using a tubing cutter. Other causes would be water quality related and could be high TDS and/or clorides content.

    If the bad spot was cut out, what did the leaking spot look like? If an elongated streak type groove, that's erosion corosion.

    Quality Water Associates


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