Steam piping

STEVEN MARKS

I am replacing a 1 pipe steam boiler. It is a small boiler 300 sq ft of steam. The supply branches of in 2 seperate directions in the basement. The 2 returns come back from the same directions head high. The old boiler the returns dropped down on each side of the boiler (no hartford loop or equalizer) each return has a main air vent. The new boiler will have the hartford loop and equalizer. My question is can I tie in both returns up high or do I need to drop both returns seperately to the boiler return?

Unknown

hmmmm

You can join them, higher than the A dimension, and have a single main vent location.

You can combine them below the water line, and then you need to vent each main separately. You can save a small amount of fuel by venting each main back at the last radiator branch connection. These will shut quicker, because the steam hits them while the rest of the return still has air in it, on each side. The water in the far ends of the mains, where they drop, seals the air in.

If you make less steam, you use less fuel. The steam stops filling the main as soon as the last radiator branch gets steam. The main vent closes, the air cushion in the main beyond forces the steam up to the rads in a shorter amount of time. The rest of the main doesn't condense steam and consume fuel, because it is airbound between the last rad and the end of the main. It stays cool until condensate flows down it.

The thermostat becomes satisfied quicker.

Noel

Steamhead

I prefer

dropping both returns below the boiler's waterline before tying them together and coming up to the Hartford Loop. This way no steam can jump from one main to the other thru the returns, as may happen with a leaking main vent.

But I've seen systems piped the other way work without banging.

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Mark Hunt

I'm with Steamhead


Tie them together below the water line and vent both mains.

I have yet to see a system with dry returns connected above the water line where steam and condensate did not jump.

What a noise that can make!

Mark H

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