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Need some help

adambuild Member Posts: 414
Domestic coil leaking, indirect leaking, expansion tank not charged right.

Good luck, Adam


  • Oilman7018_2
    Oilman7018_2 Member Posts: 5
    Need some help

    Last sunday we had a service call at work one of our tech's went on. He arrived at the house and found that the pressure relief was leaking and blowing off. He ended up finding the feeder was over feeding. So he told the customer he could shut the feeder off and get the system to stablize until tomorrow morning when we could make it back on regular time instead of time and a half. The feeder was an old Watts. The next day he went back changed the feeder added a backflow preventer and changed out the old expanison tank. Everything on the boiler for piping is very old. It is a fairly new boiler a (Weil Mclein Gold). After Replacing the feeder and the expanison tank everything seemed to be stable. The next day we get a call saying the relief valve is still blowing up and trickling. The tech goes back and replaces the relief valve, because like we all know after having one water problem you have more. Plus he talked the customer into having us come back and repipe the system so it was correct. We needed to just move the expansion tank add an air vent/airscope Etc... For some reason the tech thought that would help. Now we still have this problem of the relief still trickling and blowing off. As the boiler is running it is slowly building pressure until the relief valve is trickling or shooting off. Now we have a new Feeder,Backflow, Expanison tank No. 30, Air vents with all the air purged, New relief and some new piping. We still have the problem of the boiler building enough pressure that it is causing the relief to shoot off. If anyone could help or give me some words of advice on what they might think the problem is.
  • Mad Dog!!!!!!!!
    Mad Dog!!!!!!!! Member Posts: 157
    Yep and if it aint the coil

    Is it an old gravity system and the tank is undersized? Mad Dog
  • brucewo1b
    brucewo1b Member Posts: 638
    or expansion/compression

    tank too small for the system
  • [Deleted User]

    If the make up is connected near the pump inlet, and the pump is pumping toward the expansion tank, every time the pump turns on, the PRV "sees" low pressure and sends in water, until the relief threshold is hit and the relief valve does its thang...

    I call it the death spiral, or the circle jerk, or the viscious circle of guaranteed boiler death...

  • Weezbo
    Weezbo Member Posts: 6,232
    Very good thought.

    if you check the coil and it is good, and you just installed a feeder and know it is good, and the expansion tank (captive air) is dialed in with some 5 psi room for difugalties...then you got to go with what is the Glitch and Fix :) Mark may have caught the truth...

    one thing that can help if it is not the feeder tank location is, Flush the water From the Potable water supply First then install the check ,back flow,feeder....

    on a potable water system from a Tank,...with a differential pressure switch, i tend to think that the check valve is a necessity.
  • Ragu_5
    Ragu_5 Member Posts: 315

    For what it's worth, almost every new expansion tank is low on pressure right out of the box. Remove it from the system and check the pressure.

    The leaking tankless coil idea seems like a good candidate for this problem also. Good luck.

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  • tim smith
    tim smith Member Posts: 2,752
    over pressure

    Did you install an isolation valve after the fill valve w/ a tee between the fill and iso. This will let you see if fill valve is leaking by in a quick manner. Really helps. Maybe some debris got under fill seat. Also agree w/ mad dog that the expansion tanks put on old systems need to be oversized to take up the additional expansion of the water volume. ?? did you change out standard expansion tank to w/ the diaphragm tank, this could be the cause. Good luck, Tim
  • Ken_40
    Ken_40 Member Posts: 1,320

    The system is an old gravity with huge water content and needs an Extrol 60 (not a 30). Or...

    It is a three story house and the static fill needs to be raised to 15-18 AND THE EXTROL BLADDER PRESSURE AS WELL!
  • Dave Stroman
    Dave Stroman Member Posts: 765

    I had one once that stump me too. I ended up lowering the high limit temp. to about 160. Problem went away.

    Dave in Denver

    There was an error rendering this rich post.

  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    one of these

    AGREE with all the above
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