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Lost Art Pg 96 / 97

bean
bean Member Posts: 34
I have a Question about a steam boiler flooding.How does it flood if there is a boiler feed tank controlled by a float in the boiler?

Comments

  • Noel
    Noel Member Posts: 177
    One way is it can have a problem getting air back into the boiler after shutdown and it will suck the water out of the tank and into the boiler.
  • Jamie Hall
    Jamie Hall Member Posts: 23,159
    Another is to have the float hang up or sink... they do, you know, now and then.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,452
    Defective float, defective pump control, plugged piping to pump control, bad check valve in feed water piping. Shorted wiring to pump control. Feed water control overfeeding boiler feed tank.
  • AMservices
    AMservices Member Posts: 610
    I remember a funny story from @Dan Holohan talking about a tenant in a apartment building who had a problem with the maintenance man.
    Every knight he would remove the air vent from a radiator in his unit, run a hose from his sink and flood the boiler.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,512
    Yes, that was one creative tenant!
    Retired and loving it.
  • Pumpguy
    Pumpguy Member Posts: 645
    To expand on @bean's comment, when the boiler stops producing steam, and it all condenses, we get an induced vacuum due to the change in volume between steam and water.

    With the boiler feed tank being vented and at atmospheric pressure, the atmospheric pressure will push feed water from the feed tank into the boiler that is now at vacuum, and cause a flooded condition.

    To prevent this from happening, there needs to be a positive closing valve on the outlet of the boiler feed pump. This valve needs to be wired to the boiler control so it will only open when the boiler is calling for feed water.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • jumper
    jumper Member Posts: 2,226
    Vents are good to let air out. But ideally pressurization should be done with steam. Of course then you need some way to prevent feed pump from going on if tank is not pressurized. No knocks against Pumpguy: long ago pump vendors and control vendors made steam more complicated than it has to be.
    Pumpguy said:

    To expand on @bean's comment, when the boiler stops producing steam, and it all condenses, we get an induced vacuum due to the change in volume between steam and water.

    With the boiler feed tank being vented and at atmospheric pressure, the atmospheric pressure will push feed water from the feed tank into the boiler that is now at vacuum, and cause a flooded condition.

    To prevent this from happening, there needs to be a positive closing valve on the outlet of the boiler feed pump. This valve needs to be wired to the boiler control so it will only open when the boiler is calling for feed water.