Raising Steam main

Paul S_3

i have this residential oil to gas conversion on a standard one pipe system coming up. It was just a simple boiler replacement, but now customer wants to finish basement, problem is theres a 2.5" steam main running across the basement and i would like them to keep the steam. i have room to run the main between the floor joists in the basement ceiling but now all the risers to each radiator will be below the main when i raise it. I would like to come off the main to each riser and drip each riser into a wet return (the drip connection will be 28in above water line, maybe even more). Seems like it will work no problem....Any advice would be appreciated if any of you have done this. Again i would like to keep the steam. Thanks Paul S

Jamie Hall

Do I presume that the risers have to go horizontally varying distances under the floor joists? Any that don't -- that go up in the same joist bay as the raised steam main -- you will be much much better off to keep them coming off at the top or no more than 45 degrees off vertical from the main, and shorten the actual vertical pipe to suit.

If there is a horizontal runout, however, that won't work, of course. So your idea should work, provided you take real precautions against condensate going down the "drip" from getting into the runout. To which end, I would suggest that the upper portion of the drip -- to at least several inches below the connection to the runout -- be 2 inch (assuming the runout is smaller than that). You can probably reduce it below that point. Also, if possible I would increase the pitch back to the drip to help any condensate which does make it around the corner into the runout to drop back out.

Paul S_3

the risers do have to run horizontally across the floor joists....

Steamhead

That should work fine. Pitch the runouts 1 inch in 20 feet away from the main. Make sure the drips on the risers drop below the waterline before connecting to each other or the wet return, and you shouldn't have any trouble.

Paul S_3

thanks

Dave0176

Sounds like a lot of work lol.

Steamhead

For steam, it's worth it.

ChrisJ

Dave0176 said:

Sounds like a lot of work lol.

Since when have you been afraid of work?

Paul S_3

i will be starting this job soon....i have about ONLY 75 Ft of Cast iron Burnham 9 inch baseboard throughout the home....i believe without checking Dan's EDR book its about 3.4SQ Ft of EDR per foot? i will verify tomorrow when i get to my truck.....customer states that system worked fine for years.....all baseboard is properly pitched.....all horizontal run outs to risers are 1 inch.....at that point i will put a 2 in tee at each run out (bull of tee would feed the runout ) bottom of tee (run) would drip (2 in) a few inches then reduce down to 1.25" to a 1.25" existing wet return...im using @jaime hall recommendation oversizing the drip connections between the supply drop to horizontal run out and drip to wet return.....would you guys run a standard 2 in main that i believe can handle around 900 or so EDR ? (when steam and condensate are going in same direction)? or run a larger main lets say 2.5 in to slow down steam velocity?....i will be using a Williamson GSA-100 (258 sq ft of EDR)....with a full 3 inch dropheader.....vaporstat etc....also i will vent the mains very quick probably 1 "big mouth".....but with the small CI baseboard should i use the slowest steam rad vent possible? ive had problems with CI baseboard in the past with steam.(on existing badly piped systems)...any recommendations and advice would be appreciated.....im saving a steam system here....there other quotes were scorched air and series loop baseboard hot water system.....both systems were well over 150K btus.....thanks in advance Paul S

Paul S_3

any recommendations?

Danny Scully

Take pictures . To answer your question, 2" is suitable. I'm doing a conterflow job soon and only a portion of it will be 3", then 2.5, then 2, etc.