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Commercial Steamer Flood

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Hvacman
Hvacman Member Posts: 159
It is a real receiver tank... Float on boiler is 2 stage, first is to turn on condensate pump, second is fresh water feed straight to boiler... pump failed, second stage fill opened and due to bad check, water backed into tank and out the low vent. Second stage fill never closed as tank filled instead of boiler! And it kept running till discovery! There is a separate manual reset low water cutoff. The tank does have a float valve plumbed into fresh water, normal level is about 1/2 sight glass. Does the feed to the tank make the separate fresh water feed to boiler redundant?

I will recommend replacement of swing check with a spring check and raising the vent and well as a sump pump... the sump is there but no pump!

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  • Hvacman
    Hvacman Member Posts: 159
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    Get your boots on boys...

    My "quiet" pre-Thanksgiving day ended ubruptly this afternoon when I was called to a local church to find 8 inches of water on the boiler room floor (pit). This new Smith steamer only just got it's feet wet thanks to the housekeeping pad and height of the burner. We pumped out the pit and found that the pump on the condensate receiver tank had failed, the boiler feed valve then opened to let fresh water into system and due to a flaky check in the line from the feed pump it filled the condensate receiver till it ran out the vent... We repaired the pump and fired the system back up and found that the check would let boiler water back into tank, boiler water level would drop and the pump would refill boiler... this short cycling of pump is not good and I need to find a check that will be reliable in this installation. What do you guys use in this situation? Spring check? I'm also leery of the tank vent height... it terminates 6" below the normal water level in the boiler, isn't it practice to pipe the tank vent higher than the boiler water level? In this situation it would have not flooded, in the case of a failed pump the boiler feed would have satisfied and stopped feeding before water backed out the vent onto floor... I realize it may have eventually flooded anyway as condensate returned but flooded boiler would have certainly been caught before then. Sorry for the long winded post, what are your thoughts?
  • ttekushan_3
    ttekushan_3 Member Posts: 958
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    fresh water feed

    I think the fresh water feed should be on the vented condensate receiver. The boiler would then shut down on low water. The flood can't occur this way. A good check valve should do the trick. Nothing wrong with a spring check here since the boiler feed pump has no trouble developing the necessary pressure to open it.

    The most interesting thing I saw was a zone valve in the boiler feed line, and a call for boiler water would open the valve and then operate the pump. Absolutely no leakage this way!

    But a good spring check is probably all you need.

    -Terry
    terry
  • ttekushan_3
    ttekushan_3 Member Posts: 958
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    But only

    You only feed water into the recovery tank if you have a genuine boiler feed pump actuated by a call from the boiler for more water. If what you have is a condensate return station, then the pump is activated by a float in the receiver whether the boiler wants it or not. Either way a good spring check valve will solve the problem.

    And yes, the vent is usually placed as high as possible in the room.

    -Terry (again)
    terry
  • Chas_2
    Chas_2 Member Posts: 104
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    Spring Check Valve

    I would use a wye pattern check valve with a teflon seat. It's a special order item, however.

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  • tim smith
    tim smith Member Posts: 2,752
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    Steam boiler flooding

    Is this a new boiler installation? What did you replace. If new, you may not have enough storage volume in new boiler to handle condensate flood back after start up even though you found pump not workign properly. I usually use a feed tank set and 150 pump/low water control on boiler to feed my boiler and handle additional storage. The c.w. feed goes to float valve on feed tank. .02 worth, Tim
  • Hvacman
    Hvacman Member Posts: 159
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    Thanks Tim

    Hi Tim, Old Old church, new boiler...

    From your description, that is how this one is set up... is a feed to the tank and a feed to the boiler redundant? The first stage of the control operates the pump, the condensate receiver has a cw feed to a float valve, the second stage feeds cw directly to the boiler bypassing the tank. This install was done by our construction dept... As service techs it was dumped on us as no one from construction answered their phone the day before Thanksgiving!
  • rjm
    rjm Member Posts: 60
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    redundancy

    In my experience you can't have enough redundancy. In my company we usually install a m/m150(pump control) and a m/m51(water feeder) on larger boilers that require a boiler feed tank. If the condensate pump fails, for whatever reason, the boiler still can run with water being supplied by the 51. As condensate returns it will overfill the tank and out the vent pipe. I'd rather vent piped to a floor drain or sump when available. But it's usually piped to nothing.


  • tim smith
    tim smith Member Posts: 2,752
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    feed to tank or boiler

    We usually feed to tank only, using 150 control to feed via pump to boiler. My suspicion is that you have a condensate receiver and not a feed tank, this is why you are having flood back. You probably need a 100 gallon or so feed tank to take all the excess condensate that old boiler could hold. Thats my take on this w/ out pics. Happy thanksgiving, Tim
  • [Deleted User]
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    jr

    Which control is your primary LWCO? Which is the secondary?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,529
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    Replace the check valve wit a good Y pattern valve as mentioned in another post. The condensate vent should be raised to the boiler room ceiling. The condensate tank should have an overflow piped to a drain or to a sump pump. The water make up it is better to put the make up into the condensate tank so the cold city water will mix with the warm return but in most locations (I'm in MA) city water feed to the boiler is required.


    Is this a condensate tank or a boiler feed tank?? Do the pumps run on float controls or boiler water level controls??

    Ed
  • rjm
    rjm Member Posts: 60
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    ron

    150 as primary
    51 as secondary
    and 63 as last resort
    why chance anything
  • Hvacman
    Hvacman Member Posts: 159
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    Hey, I'm in MA too...

    That's likely why the 2 cw feeds. The pump is controlled by the 2 stage feed valve on the boiler. Do you have a mfg. and part number on the check?
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