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Too much condensation coming into boiler feedwater tank.

I have a problem where too much condensation is coming back to boiler feedwater tank which cold water input cannot overcome temperature wise causing constant cold water input which overflows tank. There are two cold water valves coming into feedwater tank. One is temperature controlled and the other is low water float valve. Have not been able to get settings of valves to get temperature to optimal 180 degrees. No matter what settings I put on aquastat controlling cold water valve, it cannot overcome condensation input temps. It seems like an easy solution would be to control condensation input but I can't find any incidence of how to do this online. So, too much hot, not enough cold and it seems like one should be able to control not only cold input but also hot input. Right now I can control cold but not hot.
My idea is to put an overflow above the condensation input gate valve and use the gate valve to meter condensation input. The overflow is necessary so that condensation does not back up into condensation system. Overflow would be diverted into water cooler used to cool blow down water from boiler.
Summary: Shouldn't both sides of the equation (hot input and cold input) be controllable? I've read similar blogs on here with same problem but haven't read about any control on the hot input side.

Thank you for any input!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 18,907
    Maybe it's obvious, but I think I need more information here. What sort of overall system is this on? What is the sources of the condensate? Why is there a need for boiler blowdown? What happens to the contents of the feed tank, other than being used to cool the boiler blowdown?

    There are some parts to the equation missing, and a full description of the system would help.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,987
    We need pictures to see what you have
  • dopey27177
    dopey27177 Member Posts: 872
    Gate valves cannot be used to meter any fluid.

    Using a combination feed tank and condensate receiver a float with or without an electric valve is used for installing new water to replace lost condensate water. The automatic feed can only be done by one pipe supplying the tank.

    The make up water only replaces lost condensate water due to evaporation and or system leaks.

    The condensate pump that is used to return the water to the boiler is controlled by a liquid level controller that is part of the low water cut off control or a separate controller inserted into the boiler.

    Normally condensate returns to the condensate receiver at about 150 degrees if the steam traps on a two pipe system are not defective.

    In a one pipe system the condensate temperatures will vary based on how long the system operates to provide heat.

    If you want 180 degree water you will need to use a heat exchanger to heat the water in te tank.

    Jake