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Noisy steam coil

We recently had a large steam coil in front of a VAV box replaced. While new in 1988, it had to be brazed several times in the past on its manifold and was leaking again. So a coil manufacturer visited the site to make his own measurements. So after the installation, the coil makes a lot of small water hammer noises. Not the traditional banging, but incessant ticking. To make a long story short, after a pow-wow with the coil guy, the service manager and the sales manager from our HVAC company, they decide to replace the F&T trap, put in 2 vacuum breaks and a vent. The noise is exactly the same! Now, the coil is apparently a tube-in-tube type, while the original was a more traditional style. Now I'm just the Director of Facilities, but over the years I've learned a lot about steam heat and replace or rebuild traps on my own. So I know a little. (I've got "The Book") There has been MANY unbillable hours on this project, so it will be interesting to see how it ends. One thing is for sure, no one is denying that the noise is noticeable and unacceptable. Any thoughts?

Comments

  • Dennis Kunkle
    Dennis Kunkle Member Posts: 34
    The latest word on this is that they may install a condensate pump "to get the water out of the coil". Surely there must be some way to prove that that is the fix.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,985
    Disconnect the condensate return from the coil at the trap outlet. Connect it to a hose or pipe it outside or to a floor drain or too several buckets. Try it and see what happens.

    You may have an undersized trap, back pressure on the return line or are you lifting the condensate from this coil?? Several possibilities. The condensate pump could be the fix if it is a condensate return problem
  • Dennis Kunkle
    Dennis Kunkle Member Posts: 34
    "Disconnect the condensate return from the coil at the trap outlet. Connect it to a hose or pipe it outside or to a floor drain or too several buckets. Try it and see what happens."

    Funny that you would say that.......that was my layman's suggestion!
  • Dennis Kunkle
    Dennis Kunkle Member Posts: 34
    Last Friday, the coil manufacturer rep was there to try something: to put a piece of sheet metal in front of coil; he feels that the 56 degree air hitting the coil with high CFMs is causing the problem. But for reasons unknown, the whole time he was there, the coil didn't make a peep....LOL. The next day the noise was back and non-stop after that. For my own test, I over-rode the computer to tell the the output damper of that VAV to be at 0% output. The airflow rate reading went to 0 CFMs to confirm it. There was no change in the ticking sound! The Sales Manager is convinced that the tube-in-tube design is the problem. The coil company rep, having never seen this issue, thinks otherwise. I don't know where this is headed.
  • Larry_52
    Larry_52 Member Posts: 181
    Look up condensate stall when you get the coil in the coil thing sorted
  • Dennis Kunkle
    Dennis Kunkle Member Posts: 34
    The coil company tech put sheet metal in front of the coil to restrict/slow down the air hitting the coil. This has apparently helped. The noise has decreased by 95%. A vent, vacuum break and check valve that were installed for good measure are ALL BAD from the factory! They will need to be replaced and then I guess we'll decide if this is over.