Filled sight glass

ted4653

I have a single line steam heating system in house built around 1920.
I know that the sight glass needs to remain approximatly 1/2 full when operating.
The sight glass on my boiler is full after it turns off and cools.
Is this to be.expecte?

Ted

Jamie Hall

No, it isn't. But let me ask: where is the water level in the boiler when the boiler is hot and steaming?

EdTheHeaterMan

If you have a long wet return line, that can get filled up with lots of mud. That will cause the return condensation to take longer than normal to return to the boiler. If the steam level in the boiler drops too much the water feeder (if you have an auto water feed) may add water during a long heating cycle in order to continue operation. Once the thermostat is satisfied, and everything settles down, the condensation may migrate back to the boiler thru the muddy return pipe. That condensation returning plus the added water from that long heating cycle may add together to make the boiler water level to rise above the desired water line.

If you are interested in finding out if this is what is happening to your boiler, you could post some pictures of the boiler and all the near boiler piping in order to see the boiler from floor to ceiling. take pictures from at least 2 or 3 different perspectives. High from the left, Low from the right and middle from front. More angles are better.