Steam Boiler Flooding

Rob Bedelis

I have a problem with a low-pressure steam boiler used for space heating (two-pipe system). Several times per day I will find that the water level is way higher than it should be according to the sight glass. I then drain enough water from the boiler to reset the water level to the specified point. I suspect that what is happening is during these shoulder months when the boiler is not at full load, I am not returning condensate fast enough so that make-up water is then added. After the boiler shuts down, the condensate continues to return to the receiver which then pumps the condensate back in to the boiler, thus over-filling it. Would it be reasonable to have the condensate pump not run when the boiler is not firing? A contractor I spoke with suggested that this is "just the way it is" and that there is not much I can do about it, which I steadfastly refuse to believe. Intuitively, I think this is more of a controls issue than anything else. Any thoughts you could offer for correcting this situation would be greatly appreciated. Thank you!

[Deleted User]

Sounds like a job

for a boiler feed unit w/ a pump controller at the boiler. The cond. unit you have hasn't got a clue to the water level in the boiler. The pump just does what the float switch tells it to. Pump the water back into the boiler when the float lifts.

If you kill the power to the existing unit when the boiler is not on, the returning water will stack up in the returns. Some of the excess may even run out the overflow. Then when the boiler starts, the pump will dump the water back into the boiler. Floodsville. And. All of that fresh water will kill the boiler before it's time.