The water level for my boiler seems to go above the labeled height. We now have a sporadic water leak that is not showing itself. Could it be that the excess water in the boiler is causing this ovrflow condition?
Water – Could excess water in the boiler cause overflowing radiators
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Should the sight glass of a steam boiler always be within the recommended range? Or only when firing
I talked to the guy who originally installed the boiler and he suggested that the pressure was probably a bit high (was set to 1.5 PSI) for our house; if the pressure is too high, then more steam than the radiators can handle is sent out at a time, and therefor the steam doesn't condense back to water at the radiators at first, so the water level gets low and the auto feeder turns on.
I turned down the pressure to just below 1 PSI and it seems to have done the trick, the water level on the site glass doesn't go down as far while the boiler is operating. Also, according to this article, steam heat pressure really does't need to be high at all, so there is no worry on my end about turning it down.
In order to turn down the pressure I adjusted the screw at the top of the box next to the pressure gauge:
A lot depends on the type of system you have. If you have a system or combi boiler, it could be the diverter valve which is faulty. This will be in the boiler itself. If you have a Y-Plan system with a three port valve, it could be the three port valve which is faulty. These are usually found in your airing cupboard or in your loft.
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Best Answer
Two common causes of overfilled boilers are a defective auto fill valve (if equipped) and the tankless coil. You can test the auto fill valve by shutting off the supply line to the boiler. If the overfill condition ceases the auto fill is the culprit. If you have a tankless water heater (a coil inside the boiler that makes your hot water) it may be leaking. The leak allows uncontrolled domestic water to enter the boiler causing the overfill condition.