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Hi All. Need a little help.

Fasthackem Member Posts: 2
Browsed around and can't seem to find an answer on the forum so I'm reaching out for some assistance.

I have a single pipe steam system where the boiler is overflowing. I have an automatic water feeder.
When the boiler is sitting idle the water level is holding steady at about 3" down from the top of the sight glass. It will remain this way indefinitely. When there is a call for heat and the boiler fires up it usually maintains the correct level for 24-36hrs of normal cycling on and off. Around 48hrs of operation I notice the water level is over the top of the sight glass. I blow down approx 3 gallons of water to get the water level to where its supposed to be and the process begins again.
I guess my question is if the boiler is holding level while idle, why is it overflowing when under operation?
Is it a problem with my feeder?
Is there a faulty steam vent somewhere?
Am I getting too much condensate trapped up in the system?
Is my return possibly clogged or restricted slowing the return of condensate? Causing the water feeder to activate, then when the system cools the slow return is causing the problem as the water returns to the boiler?

I need some help diagnosing the issue and any help would be greatly appreciated.

Thanks in advance


  • Steamhead
    Steamhead Member Posts: 15,988
    Could be the return, bad low-water cutoff, etc. Where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Fasthackem
    Fasthackem Member Posts: 2
  • Snowmelt
    Snowmelt Member Posts: 1,387
    city , up sate or staton island
    HVACNUT Member Posts: 5,024
    Seems like a partially blocked return.
    Feeder gets energized. Fills the boiler, then later the condensate makes it's way back.
    What model feeder? You might be able to adjust the delay.
    Fixing the return is better if that's the issue, but adjusting the feeder can help.
  • Ironman
    Ironman Member Posts: 7,119
    You could try closing the valve to the auto feeder. Then, if the water level goes down and slowly rises, you probably have a clogged return. If not, the feeder could be bad. The down side to trying this is that the LWCO is gonna turn the boiler off as long as the water level is low.

    Check the contractor locator above to see if there’s a steam pro near you.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Scott M_2
    Scott M_2 Member Posts: 26
    Another possibility is if your using this boiler for hot water the tankless coil or indirect may have a pin hole leak.