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water hammer

Andruid
Andruid Member Posts: 9
in THE MAIN WALL
I did a service call the other day. There was water hammer in the manifolds. It's an injection style radiant system controlled by a Tekmar outdoor reset with radiant baseboard upstairs and radiant slab downstairs. There are Roth manifolds controlled by little clip-on thermostatic(I think) zone valves. All pumps in the system are Grundfos 15-42's. The water hammer happens when the valves open and when they close. Even though the valves take about two minutes to open or close, the water hammer happens precisely when it opens or closes. I got it to stop by plumbing in a bypass between the supply and return piping in the system loop down in the mechanical room and turning the 3-speed Grundfos pump down to the slowest speed. It took both of those to stop the water hammer, but now I'm worried they won't get enough flow through the floors and baseboards. I've never seen manifolds with water hammer. What's going on and how can I keep this from happening in the future?

Comments

  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Sounds like

    you've got water flowing in the wrong direction to me...

    Only seen hammering manifolditus one time, and it's supply and returns were reversed. It sounded like someone was running into the side of the building with a truck mounted jack hammer when these babies shut.

    WHAMWHAMWHAMWHAM...

    It'd wake the dead.

    ME
  • Tom K
    Tom K Member Posts: 26


    I have had to install pressure differential bypass on sysyems that the pump was too large for only one zone.
    they are easy to install just like the bypass you put in but as will still give you the flow if all the zones call.
    I know Honeywell makes one. Dont remember the part number.
  • Steve Eayrs
    Steve Eayrs Member Posts: 424


    I too have ran into this and it was because flow was the wrong direction. Most of these type telestats will do this if pushed the wrong way. I know from experience Wirsbo and heatlink manifolds will do this if the telestats are on the wrong side.

    Steve
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
    The part number is

    D146M1032 for 3/4" and D146M1040 for 1 1/4. Available from most hydronic oriented wholesalers.
  • Andruid
    Andruid Member Posts: 9
    I asked one question . . .

    and learned more than I expected to. You guys are great. I love this place.
This discussion has been closed.

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