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Weil Mclain Ultra

LFK Member Posts: 2

 Im getting ready to pipe a Weil Mclain 155 ultra going off of the manual, This will have 4 radiant zones and 1 baseboard zone. I will also be using an indirect tank. Is there any problem piping this just like the manual shows?


  • icesailor
    icesailor Member Posts: 7,265
    edited September 2012
    Ultra Piping:

    There won't be any problems piping as the manual shows.

    The manual does NOT show any secondary loop connection through the RUN of a tee. Only a branch.

    Closely spaced tees are 4 to 6 pipe diameters. Not 12" apart or whatever one deems convenient.
  • LFK_2
    LFK_2 Member Posts: 1

    I was going to use 1 1/2" pipe and have my tees 4 times that. Does the expansion tank have to go where the manual shows? What I wanted to do was hook up the indirect the first day, have isolation valves containing the expansion tank, then spend what ever time I needed before heating season to finish up
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Does the expansion tank have to go where the manual shows?

    I am a homeowner with an Ultra 3 80. It is piped as the manual shows, but with 1 1/4 inch pipe where the manual specifies at least 1 inch. The installer said the larger piping works better. I am not sure, but it seemed to do no harm, and might be better.

    I do not think it matters where the expansion tank is (Pascal's principle) provided that the circulator(s) in the secondary (system) loop are right after it; i.e., pumping away. If you put it in the primary loop, it seems to me to be better right after the boiler (and before the take-off to the indirect) rather than on the entry to the boiler (return side). That way the boiler circulator in the return side will be pumping away from the tank, as will the circulator to the indirect..

    However, the air separators mostly come with an 1/2 inch tapping underneath where you can attach the makeup system and the expansion tank..

    It seems to me that in a primary-secondary system with W-M mod-cons, you want the air eliminator in the boiler loop (what I call the primary loop) so that the hotter water in the boiler loop, that may go direct to the indirect, goes through the boiler loop, giving better air elimination.
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