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Steam condensate return humming/vibrating

sean_pdcsean_pdc Posts: 2Member
I have a 1.6mbtu steam system that has a condensate return system that is humming very loudly in certain units. Building is an older brick structure. Stand up cast iron radiators. Steam rises up to attic and drops down to each unit, enters radiators through a standard angle stop. Each radiator has a mepco steam trap. the resonance/vibrating is happening on a couple stacks and appears to be coming from the condensate return system. We've replaced a few angle stops and steam traps and that appeared to have stopped the issue. Day later we are getting the same vibration/resonance. Any help would be appreciated.


  • JUGHNEJUGHNE Posts: 5,780Member
    Pumped return into the boiler?? Does the noise coincide with pump is really too obvious to suggest but WAG.

    Does each attic drop have a drip with trap?

    I work on a system designed this way and wonder where the vibs could come from.

    Best guess maybe valve with loose washer/disk on seat or maybe check valve in return line.

    Any steam in the return venting out of the pump?
  • sean_pdcsean_pdc Posts: 2Member
    Pump is operating fine and doesn't coincide with the issue.

    Each drop does not have a trap. Only traps are on the radiators themselves.

    I adjusted the system pressure down from 2psi to 1.5 and it seems to have lessened the vibration noise.

    Gonna end up talking to manager about replacing all steam traps and valves, most are original to system. probably 50+ years.
  • Intplm.Intplm. Posts: 777Member
    @sean_pdc You might even be able to lower that pressure even more. Try another half pound down for starters and monitor the system.
    As to your comment about replacing the steam traps. You can rebuild most steam traps. The parts are commonly available at a much lesser cost than replacing a entire steam trap.

    Look up a company by the name of TP Tunstall. They will have replacement parts and rebuild kits for your steam traps. A much better and cost effective way to go than a full replacement.

    It will be a great improvement after some fifty years.
  • nicholas bonham-carternicholas bonham-carter Posts: 7,861Member
    Barnes and Jones also supply repair kits for traps.—NBC
  • Dave in QCADave in QCA Posts: 1,737Member
    And, Mepco discs are available to do a simple repair to the existing trap and cap. I think there may be several for sale on Ebay at the moment.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Joe_DunhamJoe_Dunham Posts: 1Member
    Trap manufacturers state that a reverse flow through trap can cause "singing". This can occur due to collapsing action of steam creating a lower pressure or Vacuum on the supply, especially on old cast iron radiators. Plus the supply risers are larger than the returns (greater volume) so they are subject to more collapsing action. You may try installing a check valve connecting the supply to the return somewhere on the main, with the arrow pointing towards the main. This will equalize pressure. if its an old Dunham System, there may have been a vacuum pump instead of the plain condensate pump. the Vacuum pump (just a big mechanical air vent) would insure lower pressure on the return not to mention much more efficient and quiet and thorough distribution of steam.
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