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Replacing Exapansion Tank/TPR valve and general maintainence for gas boiler?

misterv Member Posts: 4

Hi, I have a gas boiler. In the past, the TPR valve has been leaking (dripping constantly). Someone had suggested that I replace the Expansion Tank/TPR valve. Are these generic parts that I could get at home depot? For example, i have et-30 expansion tank which is 4.5 gallons. Could i just get a 4.5 gallon tank from home depot of another brand. Also, similarly with the TPR valve, would I need a special order from the manufacturer? A friend also suggested that I replace the air filter. What else should I be aware of for general maintenance? If you could guide me in the right direction of obtaining the correct parts, I would appreciate it.


  • Jamie Hall
    Jamie Hall Member Posts: 23,661
    Well... they re generic parts. Sort of. I'm not one to knock the big box -- get a lot of things there myself -- but they don't always have the top quality.

    If the temperature pressure relief valve has been leaking constantly, you do need to replace. However, don't bother until you find out what the problem with the expansion tank is. Before you go to the trouble of replacing it, you should make sure that it really has failed, and if not if it has the proper precharge in it. To do that, your first step would be to depress the Schrader valve on it -- opposite the inlet. If you get water out, it's done. If you get no air out, it may have lost it's charge. Isolate it from the system and drain it of water, and then put air pressure in to bring it to the cold working pressure of your system and reconnect. If the system then holds pressure within a few pounds, you may be OK.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,110
    If you get a replacement relief valve, be sure you get a 30 PSI pressure only relief valve for heating boiler. Not to be confused with a water heater tank pressure and temperature relief....it has too high of a pressure setting.
  • Henry
    Henry Member Posts: 998
    Bladder expansion tanks loose 4% air per year. Do Jamie check for the expansion tank. It there is no water coming out, then you must remove the tank. Pressurise the air section to the pressure level of the system and reinstall.
  • HomerJSmith
    HomerJSmith Member Posts: 2,511
    edited December 2019
    Look, just replace the X-Tank. They are cheap and while you're at it put a Webstone valve between the tank and the boiler supply water. Also, I 'm not sure how much work you want to do, but if it were me, I would move the X-Tank from the boiler hot water supply where it is presently located to the return side where the pump is. It should be tied in at about 10" before the input of the pump.

    There is a reason to do this. You are currently pumping into the X-Tank which is a no, no. This is a common mistake that I see all the time by installers that don't understand the proper placement of the X-Tank. The movement of heated water thru the sys. is improved by the proper placement of the X-Tank.

    Where is your air eliminator?

    Also, replace the boiler pressure relief valve while you're at it, makes common sense.