What is this?

RayWohlfarth

I just visited an old building with a steam system that is about 100 years old. I saw this valve and would love to know what it is called. The radiator has this on the inlet as well as as a trap on the outlet. It is a downfeed system. Thanks
This is what I love about this industry. No matter how much you know, it has a way of humbling you.

Abracadabra

It's a Webster double service valve used specifically for downfeed systems. It's a combo trap and supply valve.

RayWohlfarth

Thank you very much for your answer

gcp13

This may help

RayWohlfarth

Thanks for the help.

jumper

My mentor experimented to economize installing steam heating in multi-storey buildings.He once tried separate supply and return connections to single pipe down feed.