This actually sits in my assistant's apt. as a conversation piece. He took his dremel to it and cleaned it up. We think it was installed about 1952. Took it out last year after babying it for a couple of years. Originally it was controlled by a small gate valve at the back porch. Eventually it was converted to electric with peter paul solenoids. It had a 1/4" tube that ran from the elbow to which it was attached to the top of the valve. Did not have a spring. My oldest documented still working valve is from 1948.