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Losing all the water in steam/oil boiler every day - changed return lines - still losing water

We are losing water in our boiler. We used to fill it once a month, then in the last 6 months we now have to fill it three times a day. We have no knocking or visible leaks in the three story house radiator/valve system. One valve in the 2nd floor bathroom spits a little steam. We were told it was the return lines and had them replaced this week. This has not worked, the boiler still needs to be filled three times a day, even though the return lines have been replaced to the boiler. No lines are now underground they are all above ground. We don't see water on the floor in the boiler room. The boiler vents to the chimney. The boiler is old, possibly original to the 1935 house. The metal is fatigued. There is not an auto feed on the boiler, there is an auto cut off mechanism when the level of water drops. The house pitches towards the boiler, so that should help the water/steam to return through the return line we thought. Can anyone help us solve this mystery. We had the return pitched to avoid knocking a few years back but the draining problem started happening a year ago. Can anyone help us work through this problem. We have had one technician and two contractors and a plumber look at everything, and they all said change the return lines. We did that and it has not worked. Any help would be very much appreciated.


  • BobC
    BobC Member Posts: 5,470
    Cracked casting?

    It sounds like you might have a hole or crack in the boiler casting that is leaking water into the firebox. On a cold day when the boiler is actively making steam check the chimney to see if there is steam billowing out of it.

    To check for this kind of leak you will have to shut the boiler down and flood it up to the top of the casting and wait for 30 - 60 minutes. If there is a hole in the casting you will find water under the boiler or inside the firebox. If there is a leak it's time for a new boiler.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
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