water consistently above site glass on steam boiler

Tom Hopkins

What steam pressure is it shutting off at? anything more than 3 psi is wasting fuel. could be making too much pressure and causing the water in float to surge, even though it doesnt look like it is. first thing I would do is make sure psi not more than 3. Then get some surgemaster treatment from your local plumbing supply and put it in boiler. See if that works, if it doesnt you might have an almost clogged steam return line. If you have drain valves on return, run up some pressure and open drain valves. They should be valves on return lines close to floor in back of boiler. But, it sound to me like it is probably making too much steam pressure. 2-3 psi is plenty and should not make a difference how long heating cycle is. Hope this helps... -Paul Astoria Fuel. astoriafuel@aol.com

Irv Auerbach

water consistently above site glass on steam boiler

My 1959 vintage (Peerless) steam boiler uses a #47 McDonnell Low Water shut-off. The boiler operates fine. The water does not surge in the sight glass. But almost after every heating cycle, by the time the boiler is ready for the next cycle (about 2-3 cycles per hour), the water (clean) is above the sight glass. I blow it off to 1/2 a glass, but it recurs. For good measure I replaced the valve, cartridge & strainer assembly, with no change in behavior. The old one was cruddy, but it did not leak. I checked it before removal. I don't think the bypass valve is causing it, because during the summer when the boiler never fires, the water level is constant. This behavior has been for about 2-3 years. Before that if you did not vary the temperature, the water level was constant from heating cycle to heating cycle. I was thinking that my heating cycle might be too long. I replaced the White-Rogers set-back thermostat with a Honeywell set-back thermostat (maybe about 2-3 years ago). I don't program any set-back features. I use the same setting (66 degrees) day and night. You are unable to specifically adjust the cycle duration, and I have it set correctly for the steam system I am operating. Any ideas would be very welcome. Thank you all.