Brown bulb in crawlspace ID??

[Mike Lamb]

Sorry I did not get a better picture. Any guesses as to what is this thing I saw in the crawlspace? It was a brown bulb attached to a quarter inch water line with a corroded shutoff valve next to it. It looked old and not in use so I didn't think much about its function at the time, but now I'm curious.

[Bill Kibbel]

Could there have been an old furnace nearby at one time?

It looks like a float valve for the old reservoir type humidifiers.

[Rob Amaral]

Ditto to BK (as usual)..