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water hammer - home 9 year old - valve open

Ken_40
Ken_40 Member Posts: 1,310
in THE MAIN WALL
the circulator being backwards!

The circulator should pump "away" from the boiler, not from the returns back into the boiler. Although what I just wrote is incorrect technically, it is almost an absolute.

The real deal on "pumping away" involves pumping away from the PONPC (point of no pressure change) which in fact is NOT the boiler, rather the point in the system piping where the expansion tank is fitted.

Simply put, if your circulator is on the return, you are sucking the water through the zones; when you shuld be pushing the water from the boiler and PONPC which will eliminate the air problems.

If really interested, the host of this website, Dan Holohan wrote the seminal book on the topic called, "Pumping Away."

You can own it and understand why your system is acting up for a pitance. I think the "ONLine store" in yellow at the top left of this pagewill get you to the store to buy your own copy.

Comments

  • gilles
    gilles Member Posts: 1
    water hammer - prevent



    I have a hot water system with three electric thermostat control zone, basement, living space and bedroom. Each time the thermostat open the valve, I am getting a water hammer. What will be the easiest way to prevent it. I know that I have air in the system, but there is no vent on the baseboard, only an auto vent on the boiler, it doesn’t seem to do the job.
    What will happen if I reduce the flow to the circ pump.
    Any information will be useful

    thanks
    Gilles
  • Dale
    Dale Member Posts: 1,317
    usual suspect

    How long has this gone on? This is also a classic zone valve installed backwards symptom. If you have always had water hammer check the flow arrow on the zone valves. Also, some of the honeywell brand zone valves did this. Does the water hammer happen every time no matter which zone valve opens or only one? Do you have a multi-speed pump like a grundfos and is it on the lowest speed (more power is seldom good)? I'm guessing you have a 3 series loop design where purging is done in the basement for each loop. To get rid of air as the other post suggested follow the pumping away design and put a modern spirovent type air eliminator in the inlet to your pump when the pump is changed to pump away.
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