Boiler Trial And Error

Marsha called me at work to say she'd had to turn our steam boiler off, because it didn't have enough water in it. Not good. It's frozen outside.

Our boiler guy told her over the phone to let it cool down and then put some more water in, but she wasn't sure how. The diagram that came with the boiler was cryptic to the amateur.

I figured it out by studying the pipes. There was some trial and error involved. First I OVER filled the boiler. Then I drained it completely. Finally I got it to the desirable half-way mark on the site glass. I turned it on again. So far so good. It's warm in here again.

Hurray, we have heat for the night.
Half empty, half full, just right.