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Pump questions

DC123 Member Posts: 69
Just curious why one would use a non-ECM pump these days? All the major boiler manufacturers (NTI, Lochinvar, etc) seem to include only non-ECM pumps as their preferred pumps for the boiler side - wondering if there's a reason for that, as opposed to recommending an ECM pump on a fixed speed setting?

Also, I think I am going to have a Vitocrossal CU3A installed - wondering what you all would recommend as the pump given two medium-sized zones with zone valves? I don't know the exact head requirements. Would you go with VT2218? VR1816? Grundfos alpha? If the latter, would you use the constant pressure or the autoadapt setting?



  • Zman
    Zman Member Posts: 7,472
    I have thought that the manufacture should provide the ECM and have the boiler control it for some time now.
    I think it comes down to cost and a market that does not understand the value.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    delta T
  • hot_rod
    hot_rod Member Posts: 19,944
    You really need more info to properly select a circulator, head and gpm.

    If you are zoning with valves, the ∆P circs are designed for that.

    Auto adapt works in most cases, it takes awhile for it to "learn" the system requirements.

    I suspect, like Europe, only ECM type will be available within a few years. The only small advantage to a PSC type pump is $$.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • DC123
    DC123 Member Posts: 69
    Even the viessmann 222F has a built-in PSC though, no? That's one I just don't understand.
  • Jamie Hall
    Jamie Hall Member Posts: 21,557
    I can think right off hand of two reasons: cost and reliability. Cost is obvious. Reliability perhaps a little less so -- but a plain jane AC motor is pretty darn close to bulletproof (I know of a number which are pushing 60 0r 70 years or more of miserable power, near lightning strikes, and other insults) which can't be said for anything incorporating solid state controls.

    Granted, if the system to which the motor is attached has widely varying demands -- such as a pump in a zone valve heating system -- or where the demands aren't or can't be known accurately, an ECM motor has a lot going for it. If the application can tolerate the occasional failure (and granted, they are pretty reliable these days) then the additional efficiency may well be worth the additional cost. Almost all, if not all, heating and cooling applications will meet this criterion.

    If the application can't...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,472
    It would really only make sense if the boiler was factory piped for primary secondary in order to eliminate other variables.
    The installer would then just be responsible for the system circ.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordy
    Gordy Member Posts: 9,537
    Pump curves. ecms in residential size may not be suitibale for higher flows, and heads of existing systems, and ecm logic delta p, or delta t. Delta t in its present form does not play nice with mod/ con logic. Delta p seems more compatible. All depends on how boiler is piped direct, or p/s. Also how system side is designed. Cost is not a variable ecms are pretty cheap.