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Horizontal Mounted Expansion Tank

Brian_18 Member Posts: 94
A while back I remember reading a thread that blasted the practice of mounting expansion tanks in a horizontal orientation. Being an engineer and not a heating professional, I could not understand why this would make any difference in the function. I did some searching around, and find documents that clearly discuss how to (not NOT to) install in a horizontal position.
Any comments?


  • ALH_4
    ALH_4 Member Posts: 1,790

    I see no reason why a horizontal tank would cause a problem. The main issue I can see is if the tank is piped so that air might rise into it rather than being purged at the air vent. Even in that case, it would still handle thermal expansion, though any fluid capacity planned to make up for air purged during initial operation would not be there.

  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557

    I agree with Andrew. The only problem I have with it is that anytime I've seen one mounted horizontally it has never been supported. If the bladder ruptures the weight could cause the tank to sag, leak, or break off.

    I would also think there is the possibility that air could be trapped in the upper part of the tank. During times of pressure fluctuation that air could get back into the system causing a nuisance noise call.
  • Ken D.
    Ken D. Member Posts: 836
    Exp. Tank

    Weather it was a standard non-diaphraghm type tank or a diaphraghm tank, pressure is still pressure and exerts in all directions. In a standard tank the threaded ports would almost require a horizontal orientation.
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Excessive torque on threads

    My take - you don't mount it sideways because there is excessive torque on the threads. Unless the tank is supported, the contraction / expansion the threads will incur because of heating cycles and the torque on the threads could cause leaks, or premature joint failure.

    Hold your arm outstretched horizontally for a minute - its not big deal. Try it with a brick and in the palm of your hand and see how your shoulder feels after a few minutes. Thats why I would never mount a tank sideways.
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