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why did this work ?

tomswell Member Posts: 2
Im replacing a 20 year old Munchkin boiler that reportedly functioned well. I appears that the primary circulation pump from day one was installed backwards. Also the air separator / expansion tank is low and on the primary loop as opposed to secondary loop ... most design drawings have the seperator and expansion on secondary loop? Weil-McLain manual also states the pump MUST be on the return line so as to avoid cavitation while sucking from supply? Reverse pump and leave it alone ? It worked for 21 years.
this is a radiant slab system. Whats wrong with this picture ?


    EBEBRATT-Ed Member Posts: 15,534
    The closely spaced tee's are not right one tee is coming off the run. You need to pump away from the expansion tank. Weil McLain does show the expansion tank on the return with some of it's CI boilers but they have low flow restriction. Mod Cons have high flow restriction so the expansion tank should be on the supply pipe coming out of the boiler with the make up water and air removal device there. Pump away from the expansion tank
  • hot_rod
    hot_rod Member Posts: 22,157
    It is not piped exactly as the manufacturer suggests, they prefer the primary pump flowing into the boiler.

    If that primary pump was flowing the loop clockwise, maybe it was at one point? judging by the air separator flow should be, might have been clockwise. Then the primary pump would be pumping away from the expansion tank also.
    The closely spaced tees will work with one connection off the run like that the Heatway Watts HydroControl panels were always built like that, the first takeoff on the run of the tee. The intended separation function is still workable, even though not "by the book"

    I think you need a complete repipe, including the manifolds. Those zone actuators are getting harder and harder to come by, should they start failing. Looks like someone has discovered that already.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • kcopp
    kcopp Member Posts: 4,432
    Sometimes odd piping has a was of muddling through... I have seen a number of munchkins piped worse still chugging away after 15 yrs. The ability to modulate is probably its saving grace.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    Your question "Why Does This Work?" is irrelevant at this point in time. If I am reading (between the lines) correctly, You want to know if you should do a "Quick Change Out" in order to use less material.

    You could and you may get adequate results. If I was tasked with that project, I would remove all the near boiler piping and follow industry norms or at least the manufacturer's recommendations.

    Respectfully submitted.
    Mr Ed
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics