New Steam Main Layout

dennis53

I'm adding a third steam main to an existing one pipe system. The new 2" parallel flow main will go around this section of basement in a U-shape and turn to a 1.25" return. Radiator run-outs will also be 1.25"
Given the 2" main will be 12-14" below the finished floor, how far in from the outside wall should I run the main? I'm thinking 2 to 3 feet away but that is just a hunch. Any suggestions, guidelines, or rule of thumb?
Thanks.

Jamie Hall

I can't think why there'd be a restriction, other than custom or convenience for swinging wrenches...

JUGHNE

Because the runouts are counter flow there is a limit to the horizontal length.
2-3' should be good for most, from what I have seen.
There are steam piping charts for this.

Have you considered making this main a 2 pipe system?

EBEBRATT-Ed

And does you boiler have the capacity for the added radiation?

dennis53

Thank you for all the comments. I've considered making it 2 pipe, but trying to keep it simple without traps, orifices, or water seals. The boiler does have the capacity, but will be cutting into the pick-up factor a bit. Thanks again,
Dennis

JUGHNE

Two pipe would give you smaller run outs. Smaller pipe to deal with.
No rad vents.
Smaller supply valves with some adjustment possible at each rad.

You will need a water seal at EOM with 1 pipe or F&T trap to dry return.
Steam main air vents in either system.

STEAM DOCTOR

You can also use a separate return main with wet returns for the supply and return mains.