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Weil Mclain Ultra 155 Leak

NJMan873NJMan873 Posts: 2Member
I took the cover off my boiler and found that it was leaking from one of the black bolts that have a hex head. Is it just a matter of resealing or replacing the bolt or is it more serious? Also what size are the hex head bolts? Thanks


  • nicholas bonham-carternicholas bonham-carter Posts: 8,087Member
    Leaky cover

    What about posting a picture?

    You won't know how serious it is until you take it apart. Some professional help may be needed here. Is there anyone who does the yearly service on this who could have a look?--NBC
  • NJMan873NJMan873 Posts: 2Member

    Here are the pics of the unit. Thanks
  • Brp814Brp814 Posts: 22Member
    Ultra Boiler servicing

    Water chemistry is very important for the Ultra boilers, because of their aluminum heat exchanger. The bolt size for the front bolts is 10mm. Has the boiler been serviced on an annual basis? Annual maintenance is also very important for this boiler too. There is a maintenance kit that Weil/Mclain makes, and it includes everything to service the boiler, even extra nuts/studs.

    Let us know how you make out. I have serviced a number of these boilers, and we have not had any heat exchanger leaks.
  • Jean-David BeyerJean-David Beyer Posts: 2,652Member
    The bolt size for the front bolts is 10mm.

    On my Ultra 3 80, the nuts need an 11mm socket.

    I wonder if we are talking about the same thing.

    I am talking about the nuts that hold the front cover of the heat exchanger onto the main body of the heat exchanger.

    Or are you talking about something else? Like the cap screws in the main body of the heat exchanger, the ones that take an Allen wrench?
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