I tried to turn off the switch for 10 minutes, and then I turned it back on (from a plumber's suggestion). The water did not fill up the tube, so I have no heat.
Your not clear on the type of boiler. Steam boiler would have a sightglass, possibly the tube your talking about. If so it should not be overfilled. You would have a low water cutoff control that would have to be reset.
something is blocking the flow of water, and needs to be corrected. This is to prevent the boiler from boiling dry and damaging the unit. You will need to open some fittings to see where the water stops.
