No announcement yet.

Thermal expansion tank

  • Filter
  • Time
  • Show
Clear All
new posts

  • Thermal expansion tank

    I think I need an expansion tank. The Temp and Pressure valve on the water heater doesn't open but when I turn on a faucet It gushes out for a few seconds and I can hear the pipes contracting as the pressure is relieved. This can't be good for the appliances etc. The city water has a regulator where the water comes into the house and I think an expansion tank is now required in new construction.

    Just a couple questions. I've got a 40 gallon hot water heater so the 2 gallon tank should be big enough.

    The way the heater is installed now in the cold water line there is a shutoff valve, a foot of 3/4 "copper pipe into a dielectric union, a 3" galvanized nipple into the heater.

    It looks like the expansion tank has a 3/4" iron male pipe fitting. I assume this means it should go into an galvanized T.

    Is this installation workable? In the rafters just above and next to the heater relocated the shut off valve in the copper cold water line, followed by copper pipe into a dielectric union, followed by 3/4" galvanized pipe into a T and an elbow down into the water heater.

    I want to use galvanized pipe because it would be stronger to support the tank up in the rafters and avoid dissimilar metals.

    Thanks or your help.

  • #2
    Re: Thermal expansion tank

    Could it be possible that your pipes are expending and contracting to temperature changes? It does happen frequently when installers don't insulate pipe from other surfaces.


    • #3
      Re: Thermal expansion tank

      What is the city pressure,you can test this with a simple inexpensive guage you can get at any DIY store.


      • #4
        Re: Thermal expansion tank

        sounds good, but use a brass nipple, not gal.

        phoebe it is