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Confounded by water hammer

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dave_myrick66
dave_myrick66 Member Posts: 6
in THE MAIN WALL
Earlier I posted a question about a customer that was experiencing mild water hammer in one radiator in his home. We have replaced all of the steam traps in the system, corrected the incorrect near boiler piping and cleaned the boiler and feed tanks with TSP. We also lifted the steam inlet of the radiator in question as someone here previously suggested and while the hammer has gotten less severe, it still persists. Obviously my customer is quite upset that we haven't been able to solve the problem and we are out of ideas on what to do next. Does anyone have any suggestions?

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  • Grallert
    Grallert Member Posts: 644
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    When you say "lifted the steam inlet" Did you pitch the rad towards that inlet/valve? That valve/"inlet" should be on the low end of the rad. Just wanted to be clear.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • Abracadabra
    Abracadabra Member Posts: 1,948
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    Grallert said:

    When you say "lifted the steam inlet" Did you pitch the rad towards that inlet/valve? That valve/"inlet" should be on the low end of the rad. Just wanted to be clear.

    Sounds like 2 pipe steam here, so inlet/valve to radiator should be at high end, outlet/trap at low end.
  • Grallert
    Grallert Member Posts: 644
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    Abracadabra said:

    Grallert said:

    When you say "lifted the steam inlet" Did you pitch the rad towards that inlet/valve? That valve/"inlet" should be on the low end of the rad. Just wanted to be clear.

    Sounds like 2 pipe steam here, so inlet/valve to radiator should be at high end, outlet/trap at low end.
    Yes of course my mistake. Careless reading.
    The hammering could be coming from somewhere other than but maybe near that rad. I would guess that there is water spending too much time in one of the supply pipes associated with that area or that rad. Have you checked pitch of the piping?
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • dave_myrick66
    dave_myrick66 Member Posts: 6
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    All of the piping is hidden in the walls. It is a two pipe system with the steam entering the radiators at the top on one side and exiting the bottom of opposite side through a radiator steam trap.
  • Jamie Hall
    Jamie Hall Member Posts: 23,345
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    Somewhere on the feed to that radiator there is a low spot -- bad pitch or a sag. It takes very little. Until you find it...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Grallert
  • Fred
    Fred Member Posts: 8,542
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    Do you actually hear the hammer in the radiator or does it sound like it might be in the supply pipe? If it's actually in the radiator, I'm wondering if the return side of the radiator might have a build up of crud in it causing a build up of condensate before it is able to drain through the trap. Did you look in that end of the radiator when you replaced the trap or did you just replace the element in the existing trap?
  • dave_myrick66
    dave_myrick66 Member Posts: 6
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    Jamie Hall said:

    Somewhere on the feed to that radiator there is a low spot -- bad pitch or a sag. It takes very little. Until you find it...

    This radiator is fed by a vertical riser.
  • dave_myrick66
    dave_myrick66 Member Posts: 6
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    Fred said:

    Do you actually hear the hammer in the radiator or does it sound like it might be in the supply pipe? If it's actually in the radiator, I'm wondering if the return side of the radiator might have a build up of crud in it causing a build up of condensate before it is able to drain through the trap. Did you look in that end of the radiator when you replaced the trap or did you just replace the element in the existing trap?

    The hammer is actually hitting the shut off valve to the radiator and the radiator is fed from a vertical riser.
  • Jamie Hall
    Jamie Hall Member Posts: 23,345
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    Well then, figure out what is suspending a slug of water in that vertical pipe in such a way that it can hit the shutoff valve. I can't think of one, but...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Fred
    Fred Member Posts: 8,542
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    dave_myrick66 said:

    Fred said:

    Do you actually hear the hammer in the radiator or does it sound like it might be in the supply pipe? If it's actually in the radiator, I'm wondering if the return side of the radiator might have a build up of crud in it causing a build up of condensate before it is able to drain through the trap. Did you look in that end of the radiator when you replaced the trap or did you just replace the element in the existing trap?

    The hammer is actually hitting the shut off valve to the radiator and the radiator is fed from a vertical riser.
    Are you 100% sure the radiator is fed from a vertical straight up into that valve? Is this radiator on the first floor? It would still have a horizontal run-out from the main. If it is on the second floor, unless it is recessed in a wall, or the steam pipe is outside the wall, in the room below, it has to have a small horizontal section under the floor.
    Is their any nipple between the radiator and the supply valve that may be bushed down significantly and holding water

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