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Pump Sizing

I just spent 3 days dissecting a do it yourself radiant pex job. Where the homeowner installed his own piping. I used the upanor software and sized the whole job using his loop lengths. I am zoning by pump. I have 4 different head losses and gpm's I asked my supplier for the pumps based on the sizing and he said just install Grundfos UPS 1558 variable speed pumps. If they pump too fast the worst thing is that the water will come back too warm but it is running faster and will all come out in the wash anyhow.

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  • Rich L.
    Rich L. Member Posts: 414

    You could do it that way Andy and probably get by but would you be doing any better than the DIYer? To properly size the pump you would use your head losses and GPM's and get grundfos' pump charts showing pump curves and match the pump to the load against it for maximum efficiencies.
  • ALH_4
    ALH_4 Member Posts: 1,790
    Circ sizing

    You will save electricity by properly sizing the circs. Will the 15-58's be close on speeds 2 or 1? Replacement cost and availability is good on the 15-58.
  • virtualplumber
    virtualplumber Member Posts: 35

    The pump curve is only one line. I don't know if the line changes with speed. cannot get an answer.

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  • ALH_4
    ALH_4 Member Posts: 1,790

    There are 3 curves for the 15-58. They also change slightly if you remove the flow check, though with zone pumping you probably do not want to do that. This file takes a little while to download, but it has all the curves you could want.

    UP Series Circulators
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