Need help with steam piping setup I've never seen before!

Doobs

I recently checked out a four unit apartment building a friend of mine purchased and it has steam piping arrangement I've never seen before. The radiators are two pipe steam that are supplied from steam main and radiator condensate returns come right back down into to the steam main a few inches from where steam goes up. There are what look like steam traps just before where the returns tie back into the main. (The traps look kinda look like swing checks.) Stamped on the trap covers is Pratt & Cady of Hartford, Ct. The system piping arrangement reminds me of a mono flow forced hot water system. He is suffering from uneven heat throughout building. None of the piping is insulated and I will have him address that in the very near future. Has anyone seen anything like this? I want to help straighten this thing out for him. There are also air vents on the radiators.

JUGHNE

So is it a one pipe counter flow steam main with 2 pipe rads?

No return pipe back to boiler?

aircooled81

Really neat. Ive never seen this. I would love to hear how it works. I can assume those are check valves, as steam traps would have a difficult time evacuating condensate with the same pressure on both sides. So the check idea sounds more realistic, just weight of water (condensate) opens them, and they close when the steam wants to get in?
Air vents on the radiators because the check valves would just put air back into the steam main?

Steamhead

That's right, they're check valves, not traps. This was a way to use a 2-pipe radiator hookup without running a return main.

If you have a rad that doesn't heat because water is backing up into it, make sure the return line is clear and the check valve is working.

Then vent the steam main as we would any steam main.

JUGHNE

That check valve seems to have an extra port/plug in it.....is it something special?

Does each return then go back into the side of the steam main with the supply coming off the top or at a 45?

There was another system like this posted maybe 3 weeks or so ago. Check valves for each rad going into a common vertical?return.