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Baseboard water hammer?

Johnny5Johnny5 Posts: 5Member
Hi guys, wondering if you could shed some light on this problem I am having. It is a renovated boiler room from an old 1967 C.I. boiler to a new Weil-Mclain. As you can see from the drawing this is what it looks like now. The original set up was without the Pressure Bypass Valve and compensator. Both Z.V. are pointing in the proper flow direction and the expansion tank is new (Amtrol 30). If you have any suggestions on how to stop the noise it would be greatly appreciated.

Thank you
John Hieb

Comments

  • Johnny5Johnny5 Posts: 5Member


    Hi guys, wondering if you could shed some light on this problem I am having. It is a renovated boiler room from an old 1967 C.I. boiler to a new Weil-Mclain. As you can see from the drawing this is what it looks like now. The original set up was without the Pressure Bypass Valve and compensator. Both Z.V. are pointing in the proper flow direction and the expansion tank is new (Amtrol 30). If you have any suggestions on how to stop the noise it would be greatly appreciated.

    Thank you
    John Hieb
  • Sweet_2Sweet_2 Posts: 143Member
    water hammer

    Id be looking at the bypass setup. With 290 ft of pipe your looking @18 ft/hd, just about max on nrf 22. Bypass may be to large . Adding second pump might help flow issues.
  • Johnny5Johnny5 Posts: 5Member


    Thank you for the input sweet, and I did fail to mention that the compensator,bypass valve and expansion tank are all recent installs to combat this problem. The hammering started when the plumber switched the old boiler to the new 2 yrs ago.
  • Sweet_2Sweet_2 Posts: 143Member
    water hammer

    The reason for the bypass Im assuming is because there was a concern that the pump was to large? Check G.P.M needed for sytem to rule out any pump issues. When you get the hammer, are the zone valves opening or closing by chance? Did the bypass help at all.
  • Johnny5Johnny5 Posts: 5Member


    the bypass help for about 4 days and it started hammering again. the z.v.'s are 4 wire to run the pump on the end switch. we diconnected the end switch and run the pump 24/7 but it is still hammering. could enough of a air lock create this problem?
  • jim_49jim_49 Posts: 24Member


    You never said what your temp and press. are at????
  • Allan Black_2Allan Black_2 Posts: 7Member
    water hammer

    The subject is always interesting. The idea that a sudden change in fluid direction can cause so much noise and damage. But moving fluid has inertia. A zone valve springing shut at just the right time can result in water hammer. It only takes a split second. I/O reset helps because lower water temperatures at higher outdoor temperatures means that thermostats with electronic P+I or properly set heat anticipators won't rapid cycle zone valves. Proper pump size contributes to a solution as well because zone valves don't like to operate outside of their pressure differential design parameters. The placement of your differential pressure regulator is probably ok. However, I usually recommend that it be at the end of the supply circuit (attached is a PDF'd slide from one of my presentations). I probably shouldn't say this, but I'd suggest you investigate a Caleffi zone valve (I'm biased I guess). It has solved many water hammer complaints through it's design. It has a large internal body cavity relative to it's Cv rating, plus unique actuator operation (motor disengages (no motor backspin) on valve closure and free motion of internal gearing seems to stall just long enough to let a pressure spike slip through before the paddle actually closes off). Good luck with your results.

    Regards: Al
  • Allan Black_2Allan Black_2 Posts: 7Member
    water hammer

    The topic is interesting. Hard to beleive that a sudden change in fluid direction can cause so much noise and at times, damage. But, fluid in motion has inertia and I repeat, it is the sudden change in fluid direction that causes the noise. A zone valve closing off at just the right moment can cause a sudden change in fluid direction. The placement of your DPR is probably ok. However, I usually recommend it be placed at the end of the supply circuit,as if it was the last zone in the loop (attached is a PDF'd slide from one of my presentations). Pump size is also important. Zone valves don't really like to operate outside of their pressure differential rating spec. If you can set your DPR to offload about 30% of pump head pressure with all zone valves closed, this may help. I/O reset is also a good thing. Lower water temperatures at warmer outdoor temperatures means less rapid cycling of zone valves (provided of course that thermostats without electronic P+I logic have properly adjusted heat anticipators). One last suggestion (forgive me for my bias) is to investigate using a Caleffi zone valve. The internal valve body cavity is quite large relative to it's port size (Cv rating). This coupled with the actuator operation (*motor disenages from spring on closure to prevent motor backspin while increasing close-off rating, spring rewinds paddle only with limited "free motion" in a unique idler gear) all adds up to a paddle that can actually stall a split second long enough to let a pressure spike get through without water hammer (no sudden change in direction). I don't guarantee this, but I've seen it in action enough times to believe in it. It's just an interesting bonus that came out of a *design that was really meant extend motor life and increase close-off ratings.
    Good luck with your solutions.

    Regards: Al
  • SlingshotSlingshot Posts: 6Member
    Zone Valve Hammering

    Working for a wholesaler, I get alot of pesky problems thrown my way from contractors. Over the years I have approached both manufacturers and their reps about banging valves and they always say that they were not aware of the problem and I was the first person to mention it and promised to check into it and get back to me. (sound familiar, Mr.H?) The tinkers in the trade stumbled upon a few remedies, some more effective than others. Like taking one of two springs off certain kinds would make the valve close slower so the hammer wouldn't be as noticable. I had a guy tell me, as if he was telling me a national security secret, "I know how to stop Erie valves from banging" he said as he rubbed his hands together. "Just turn them around and but them in with the flow backwards, From "B" to "A" in stead of "A" to "B". Soon all the "smart guys" were doing this, thinking they were fooling Mother Nature herself. The "Smarter guys" were doing this a long time before that because that's what the directions (who ever reads them?) said to do.
    In your case wouldn't the easiest way out of this be to use circs instead of valves, considering call backs/time /gas etc?
    Also, by removing the endswitch from the equation you could be adding to the problem if the dif bypass is not adjusted properly. When only one zone is being used and the call for heat is satisfied, the zone valve starts to close and immediately stops the circ..no hammer. I know you have two valves but it might be something to consider.
    J.O.
  • Johnny5Johnny5 Posts: 5Member
    Baseboard water hammer?

    Thanks to slingshot, Al and jim for your ideas. They are all great ones, but did not help. The hammering is happening only when the zone valves open and yes they are in the right direction of flow. We flushed the system on the Friday to rule out air lock and it is still doing it. The bypass is set to keep the boiler safe. The plumber said he set it around 13-14'hd. That would mean all excess flow and pressure would go on to the baseboard. The only other thing I can think of is to change the zone valves? All this cost is coming out of the plumbers pocket. Is this the only option left or is there others?
  • Al GregoryAl Gregory Posts: 260Member


    Are the zone valves fast acting? You said 4 wires so I take it the are not Taco valves. I used watts zone valves a few times and the hammer was awful
  • clammyclammy Posts: 2,261Member
    zone valve location

    Are your zone valves located on the supply if so put them on the return and pipe your by pass as a system by pass meaning from your pump outlet to your return after your zone valves this should get rid of any velocity noises from opumping towards your zone vale .A 1 inch system by pass with a globe valve for throtling should be fine also was the direction of the systems flow reversed and where there split supplies or returns on the original sytems there may be check valves under the basboard cover i've ran into this my self as dan would say sometimes you gotta get out of the boiler room and nose around look for hidden flow check or usually piping good luck and peace clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
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