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Help relocated undersized expansion tank on Weil-McClain gas boiler CG-8 series 12

jrap76 Member Posts: 4
I am having trouble with relocating an undersized expansion tank on my gas boiler. Currently it has an EX 30 but needs an EX 60 expansion tank that will not fit in current location. Plus I do not believe the expansion tank is supposed to be hooked up there anyways.

The system has 4 zones with the circulators on the return side with bleeder vents on all four returns lines and 4 Taco flow checks on the supply side. The Weil-McClain boiler gives you a 1/2”npt nipple tnext to supply outlet to attch either a Closed Expansion tank to it Or a Air bleeder vent when using a diaphragm style expansion tank. Then I guess the diaphragm expansion tank would go somewhere else?

Currently there is a diaphragm style expansion tank along with an air vent attached to the half-inch nipple so I don’t know if this is okay because I think it’s kinda dead ended? I’m not sure. Plus the ex-60 doesn’t fit so I have to reconfigure something.

So now I’m left wondering do I either mount the bigger tank against the wall and use that same half-inch fitting to pipe it to it with the bleeder vent or do I need to redo the supply header and attach the tank there before the flow checks? And Should I install the tank to some sort of spirovent while I’m redoing it or would the 4 air bleeders on return line be enough. I’ll try to enclose a drawing and pics



    JUGHNE Member Posts: 9,765
    What problems are you having that a larger tank will fix?
  • jrap76
    jrap76 Member Posts: 4
    The expansion tank feels full and the rise in temperature of the boiler is starting to lift the safety. I don’t know how long these tanks are supposed to last but I had replaced this one about 6-7 years ago with what was there (an EX-30). The boiler Output rating is like 200,000 and the IBR is 176,000. From 175,000 and up Extrol recommends using an EX-60. So I don’t know if this Tank is failing prematurely because it’s undersized.
  • unclejohn
    unclejohn Member Posts: 1,757
    You could shorten the pipe and put a 60 there. I would mount it with the tank down not up and leave it right there.
    HVACNUT Member Posts: 4,595
    Like @unclejohn said, shorten the nipple. Don't know if there's room to hang it down. If it needs to stay up, don't use tape on the fittings, only compound or the weight might swing at the joints.
    Is there room to put in a tee and 2 #30's?
    Nice craftsmanship by the way.
  • jrap76
    jrap76 Member Posts: 4
    Thanks. No, I don’t have the room to face it down. I was just worried about the weight of the 60. Plus I have the flue right above there so it might be too tight. I just don’t know if I can leave it there or move it on the supply somewhere along with a spirovent or something like that.
  • Jamie Hall
    Jamie Hall Member Posts: 18,966
    There is no practical limit on the length of pipe or fittings needed to hook up an expansion tank -- the flow velocities are very very small. You do want to make sure that air can't get to it if you are using a diaphragm or bladder style tank. That's about it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kcopp
    kcopp Member Posts: 3,990
  • jrap76
    jrap76 Member Posts: 4
    Thank you. I have been looking for those straps at the big box stores even some plumbing supply houses but they don’t have them. Maybe it’s an online only item.
  • newagedawn
    newagedawn Member Posts: 586
    how many btu is the boiler, the tank is rated off that, maybe its just time for a new one, the do fail, you can check extrols site to verify
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"