Weil McLain hot water radiator with ballcock

gtots

We have radiators throughout our house but this is the only one with a ballcock in it. It's never had water in it....and I'm wondering if I should put water in? The well is about 2.5" deep. It sits inside a longer box but that box contains a sticker with the Weil McLain name on it and other information that I can't see clearly due to dust (was able to clean off some without ruining the sticker and that's how I know the manufacturer) so I'm assuming I don't want water to go in there. Also in that longer box is a raised pipe, an overflow valve is my guess, but I followed the pipe down and it's open under the radiator!
Any information at all is appreciated. It's really dirty (dust caked on the heating fins (? What are they called?) inside and I don't know the best way to clean it. It does heat up but I wonder if I can get more heat from it if it was cleaner? Thanks!

SWEI

Looks like a humidifier pan. Nice!

FranklinD

Looks like a humidifier. The ballcock would keep the tray full of water (like a toilet tank) and the heat from the radiator would evaporate the water. My mom used to put pans of water on our rads in the winter when it got really dry...same concept here, I believe. Pretty cool! As for the pipe, I'd imagine that it was an overflow that was never piped all the way to a drain.