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Old Expansion Tank Draining

night73 Member Posts: 1
I have an older expansion tank and I know it needs to be drained. I am confused though since it is so old. Once I have the hose hooked to the drain (in the back of the picture), do I also open up this other valve (in the front of the picture)?


  • billtwocase
    billtwocase Member Posts: 2,385
    how do you know

    is the relief valve popping, or pressure high. From the pic, the valve to the left that is tied into the system needs to be closed, start draining the tank, then slowly open the valve to the right to let air in. Make sure you turn the switch for the boiler off. If it runs, the pressure will build due to the valve closed, and nowhere for the expansion to go.
  • icesailor
    icesailor Member Posts: 7,265

    That drain valve on the left is a type that you put a hose on and screw the valve all the way open. When all the way open, it shuts the tank from the boiler and drains the tank. There should be a plug on the side if the valve, When you remove the plug, it lets air into the tank through a tube that goes to the top of the tank and breaks the vacuum. If this is what you have, when you put the plug back, be sure you wrap the plug with teflon tape and paste or air will leak out of the valve. Draining the air out.

    If you haven't drained the tank in years, it may or may not need to be drained. I would say that it does. But I'm not there.

    As old as the tank and valve are, the valve washer is probably shot and will leak, Good Luck.
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