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Water disappearing from sight glass before boiler even turns on
Hi, My thermostat is off, as we won't need heat for another few weeks. I inspected by gas powered steam boiler and tried to manually add water. I opened the valve and there was a long delay before the water level went up on the sight glass but it finally did. I came back an hour later and the water level was all the way back down. I repeated this and same thing happened. There are no visible leaks so where could the water be going? Again, this boiler isn't even on so its not steam loss. I do notice brown gunk and the within the bottom of the sight glass.