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Steam boiler floods but only after running

Do the return lines enter directly into the boiler or is there a condensate receiver pump?

If there is no pump, are the returns "wet returns", (below the operating water level of the boiler?

Ed Carey


  • Irv Auerbach
    Irv Auerbach Member Posts: 4
    Steam boiler floods but only after running

    My 1959 vintage Peerless natural gas fired steam boiler floods but only after running. It has a No. 47 McDonnell-Miller automatic water control. But I do not think that is leaking because in the summer time when the boiler does not run, the level in the glass does not change. If the boiler runs - sometimes even one cycle - the water is above the glass. I then blow it down till about half a glass is visible. I am suspecting that perhaps the 1-way check valve located in the water supply line just before the water enters the boiler may be allowing steam condensate to leak into the boiler. This check valve is only a few years old. I am wondering if it was installed facing the right way. There is also a (larger) check valve on the 2-inch black pipe condensate return line to the boiler. This has been going-on for about 2 heating seasons. Before that, if I did not allow the thermostat setting to vary, the water level would remain fairly constant through many heating cycles. How can I conclusively fault-locate what is going-on with my heating system. If additional information is required, please email me. Thank you.

    Irv Auerbach
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