Steam boiler of off, losing water

dra

my steam boiler is power off , pilot still on , i see no leaks , but the water level still drops in glass tube every few days a little , where is water goin,?

pecmsg

Return line underground?

Jamie Hall

Any number of places. Is the water level still above the Hartford Loop? If so, wet returns are likely candidates. If not... hmm... check that boiler very carefully. It may be that the pilot light is generating just enough heat to conceal a small leak in the boiler...

dra

no , return line is above ground

Jamie Hall

dra said:

no , return line is above ground

Above ground doesn't mean it can't leak. Is it below the boiler water line? Then it can...

HVACNUT

Is it auto feed? Is it getting low enough where it's adding water?  
Like Jamie said, especially if it has a flue damper, the block could get warm enough to at least contribute to evaporation with a crack above the water line.

Start it up and watch for white smoke out of the chimney. It's not an ironclad diagnosis but it's a start.

BobC

Lay some newspaper under the edge of the boiler and any return lines that are near the floor. that should find any slow leaks .

If it doesn't find any I'd start to think it's linking into the firebox or directly onto the gas tubes of an atmospheric boiler. I would then sut the piulot off and lay newspaper under the burner tubes to see if you pick up a leak.