Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Steam boiler flooding

Tim_21 Member Posts: 2
We replaced a 400K gas steam boiler and now the boiler keeps flooding. I beleive this is because the steam capacity is not the same as the old boiler. I've been told to add a hydro level 450 to the system to delay the LWCO / auto fill valve from flooding the boiler. I also think I was told many years ago to add a stand alone tank next to boiler with tappings for the condensate return and one at the top and bottom so that the boiler has the storage capacity. The theory is that the water will seek its own level and stop it from drawing the water level down to much during a high demand period.Can any one else come up with an alternative or let me know if the time delay in the hydro level will solve my problem.


  • Mark Woll_2
    Mark Woll_2 Member Posts: 67
    I believe a total solution would be a boilerfeed pump

    Assuming no other part of the system was changed other than the new boiler, the flooding may be due to the differing water capacities of the old and new boilers. Did you put in a boiler sized correctly to your computed EDR load? How does the new compare to the old equipment in sizing (both in BTU rating and--and importantly--water capacity?). If the old was really old it likely held far more water than your new one.

    If you install a time-delay based waterfeeder control, it might work, depending on how close you can set the delay cycle to match the boiler's steaming rate and condensate return time/quantity.

    I personally would be more comfortable with a boilerfeed pump(preferably duplex for redundancy)and condensate receiver running off of, say, a McDonnell & Miller 150 combination LWCO and Pump controller.

    However, this would be a little expensive. But it would probably solve your problem entirely.

    Do you have any pictures of the new and old?
  • Tim_21
    Tim_21 Member Posts: 2
    Boiler flooding

    Thanks for the input, Weil-McLain confirmed my thought on useing a resevior tank for added capacity and sent a drawing to me. I will post this drawing for any one to see in the future. Thanks again for input.

    Tim Lashar
  • Steve_210
    Steve_210 Member Posts: 646
    I know this is a very old post

    But I was wondering if anybody had more info on resevior tanks
  • nicholas bonham-carter
    My reservoir tank

    Here are the details on mine:


    First, I would turn off the valve to the auto/over-fill, and then watch its behavior.

    Has the boiler been skimmed to stabilize the waterline? Is the pressure nice and low(ounces)?

    My problem was a horizontal pipe in the returns which was just above the waterline, and when the boiler began to fire, the rising pressure tried to raise the level in the returns to a certain height. Naturally, a 12 ft section of pipe holds enough water to starve the boiler, and shut it down.

    I think the water content of most boilers is adequate to fill the system with steam without starving the boiler, so try other procedures before putting in the tank.--NBC
This discussion has been closed.