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Pump location concerns

I am installing a 5 zone system with the radiant plumbing located on 2nd floor. All zones are on the first floor in slabs. The average high point of the system is approximately 16' above the tubing. As a retired civil engineer remembering my hydraulic courses technically speaking the water in the tubes will have 0 feet head. Of course add-in pipe friction losses and a few more feet of head should be all the pump would have to overcome to move the water. What's the opinion on moving the water...push or pull? In other words should I put the pumps on the return side for suction feed or on the supply side "pushing" the water through the tubes or no difference at all?


  • hot_rod
    hot_rod Member Posts: 16,312
    Technically speaking the device is a circulator, not a pump per say. It caused fluid movement by creating a pressure difference between suction and discharge side.

    Correct you are that the circulator in a closed loop piping circuit, is sized to the resistance, or "head" that the piping circuit establishes.

    The main point is the circulator always pushes away from the expansion tank connection, referred to a "pumping away".

    The bookstore at this site has the best reading on the concept.

    Also some equipment manufacturers have suggestions for where the circulator is positioned. Many of the new high efficiency boilers prefer that you pump into, not away from their boilers.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTechErin Holohan Haskell
  • hlothridge
    hlothridge Member Posts: 2
    Thanks I'll check-out the bookstore.
    EBEBRATT-Ed Member Posts: 12,005

    In a closed loop system the pump location as far as the pump goes does not matter. It will pump the same no matter where it is. But you should pump away from the expansion tank. Any high resistance in the circuit is best on the pump discharge.

    As far as a boiler is concerned I would pump away the boiler. One concern is pump discharge pressure making the boiler relief valve open.

    That is usually a concern only on commercial jobs.
  • ratio
    ratio Member Posts: 3,178
    There's also a significant resource at Caleffi, check it out.