Flooded steam boiler, how to drain?

mattm

It appears from the sight glass that my steam boiler is flooded (the water is all the way beyond the top of the sight glass). This is accompanied by crazy banging. I've noticed this happening after it warms up after a long cold period. Presumably, the pipes get cold and all the condensate is filling up the boiler?

The problem is that I have an auto refill, so when I drain the water, it obviously fills back up. In the attached picture, how do I shut off the autorefill water supply so I can drain enough water to get it back to something sensible?
Thanks in advance!

Ironman

Close this valve:



That's a combination low water cut off and fill. It should be blown down weekly and taken apart and cleaned yearly.

mattm

Thank you! I blow it down weekly (every time I go do my laundry). Which parts require the yearly cleaning?

JUGHNE

You should blow it down when burner is on, run for maybe 5 seconds.....the burner must shut off and you should hear water flow. The water in the sight should drop when this is done and quickly return once you close the blow down valve.

You could have sludge holding the float down which should not allow the boiler to run.

So you could run out of water and dry fire the boiler which at the very least would crack the block.
This LWCO is meant to avoid that or at worse an explosion.

Also the top valve on the horizontal pipe must be shut off 100% or water will seep into the boiler constantly.

The entire thing needs to be taken apart and cleaned.
It is recommended to replace the entire assembly if over 10 years old.....especially if it has not been cleaned periodically.