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Sight Glass level vs. PSI / Where does the water go?
Water in the sight glass drops as the pressure rises. I have a one pipe steam system with 3 mains loops and a Peerless oil boiler. The system was balanced so that this season it ran nicely at .2 (two tenths) PSI and everything worked fine. Recently for some reason the pressure has increased (I don't know why) to about 1.5 PSI maximum. As the pressure rises the water level in the sight glass drops until there is no water in the sight glass so the LWCO kicks in and the burner turns off. This happens as the pressure reaches about 1.5 PSI. The boiler is piped with a Hartford loop by the way. Then as the pressure drops the sight glass fills back up with water and the burner kicks on again. The system continues to short cycle this way. The radiators get hot and the thermostat works. Where does the water go? What happens? Any ideas about this? Thanks