Say Steamhead...some odd steam piping...BP

Boilerpro

Looking at a one pipe steam system for boiler replacement. Steam main runs out about 10 feets and then splits in two. Loop 1 loops around feeding rads above boiler room. Loops 2 loops to the other side of home feeding rads and then comes back into boiler room. Now the odd thing. The ends of both steam mains join back together at the ceiling and then run about another 10 feet and then drop down into boiler water level. I would thnk this could cause venting problems and steam would end up feeding into loop 2 from both ends of the main. Thinking I should separate ends of mains at ceiling, install main vents,and then run each loop down to water separately. Sound right? Thanks!

Boilerpro

Steamhead

You're absolutely right, BP

you'll never get Master Venting to work with the returns piped like that. If one main is shorter than the other (which is what it sounds like from your description) the steam will shoot thru the short main and close both main vents. What's to stop it?

This wasn't a big deal in the old days because the coal fire burned all day. Once the air was out, it pretty much stayed out. So what if the system took an hour to heat all the way to the end?

If you run into a similar situation and don't have access to all the return piping, a loop seal at the end of one of the two mains will do the same job. Since the pressure is pretty much equal on both sides of such a loop seal, a seal depth of 3 feet will do fine. I did this at a neighbor's house and it worked great. Remember to put a drain at the bottom of the seal for cleaning and freeze-up prevention.

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Boilerpro

Thanks!

I was thinking loop seal too, but the run of new piping is so short I am going to recommend running a new return.

Boilerpro