Steam main size

Patrick_North

<span style="font-size:12pt">I posted earlier about some one-pipe steam main repipe issues- here’s another one: size.</span>

<span style="font-size:12pt">After removing and/or downsizing several radiators, we’re down to about 500EDR. This may go down a bit more as I find replacement radiators better suited to individual room needs. The repiping work will leave me with 2 mains serving roughly the same EDR, let’s say 250 each. </span>

<span style="font-size:12pt">Currently, the mains are 2.5”, but the repiping will mean replacing almost all of it. The boiler header and risers are all fine as is. I know price isn’t discussed here, but I think I can say that sticking with 2.5” will cost me roughly double than if I went with 2” (seems to be quite a jump in $$$ for fittings and such, and I guess 2.5” involves a different, more expensive threader). </span>

<span style="font-size:12pt">Dan’s books among others suggest that 2” mains would amply handle this load, but there’s also a general suggestion that bigger is better- lower pressure, better distribution. I intend to vent the beejeezus out of the mains, as I do now, a la Pajek/Gill. I don’t want to be penny wise and pound foolish here, but I can clearly see how much more the larger pipe will cost me, while the fuel saving benefits are murky at best. Maybe it’s night and day, maybe it’s all but unnoticeable.</span>

<span style="font-size:12pt">What do you say, guys? </span>

<span style="font-size:12pt">Thanks,</span>

<span style="font-size:12pt">Patrick</span>

Charlie from wmass

Patrick If Dans the charts in Dan's book

say 2" will be ample then you should be fine. I will double check the size later in the books I have here. The labor for 2 1/2" is also much higher as cutting and threading requires a whole different setup. Pitch and proper drips are still needed and more so you would want to keep it a parallel flow as opposed to a counter flow.

Steamhead

I agree

with less then 386 square feet on a main, 2" is the way to go if you're gonna repipe completely. But since your existing mains are 2-1/2", why not just leave one main in place in front and one in back, and hook up all the existing radiation to the remaining mains? 

Charlie from wmass

Just thinking of labor vs. material

I think the 2" would win as opposed to reusing the 2 1/2". Granted I do not know who Patrick is using to do the installation.

Patrick_North

Thanks!

Great to hear- it's comforting to know that wouldn't be a bad move. Steamhead, while your idea is a possibility, the existing mains are such a crazy quilt, trying to splice them together could be more trouble than it's worth. It's still on the table, but i'm glad the 2" is a viable alternative.

Thanks again,

Patrick