Main venting

thfurnitureguy_4

Did a test last night to see how well vented my system was. The wide open main through a 1" pipe fitting, vented in 10 min (warm start). 5 Gorton #2 in line on a 1/2" pipe vented in 15 min. 6 Gortons split into 2 banks of 3, fed out of a 3/4" pipe brought it back down to 10 min. Another tidbit about pipe insulation. In my case where I have 2 nearly identical runs, 1 with insulation and the other without. During the cold start it took 30 min. to close the vents on the insulated side and only 15 on the uninsulated side. On the next run when the pipes were warm they both closed within a min. of each other!

Rodney Summers

Wonderful numbers

Thanks for studying your system. All your numbers make sense to me.

David Hohengasser

Insulated took longer?

Why did it take longer (30 minutes) for the main vent to close on the insulated pipe? Wouldn't the insulated close sooner?

Mike G_2

Insulated took longer?

"During the cold start it took 30 min. to close the vents on the insulated side and only 15 on the uninsulated side. On the next run when the pipes were warm they both closed within a min. of each other!"

Remember, it was the COLD start that took longer. From a cold start, the insulation had cold air in the dead air spaces that had to be heated first. That cold, dead air contained within the insulation kept the pipe at a cooler temperature longer than the uninsulated pipe. Steam in that pipe cooled and condensed for a longer time until the pipe warmed, hence the long-in-closing vent.

However, from a WARM start, the insulated pipe now had warm, snuggly air next to it that did not have to be heated. The steam remained steam and closed the vent quicker. That's where pipe insulation starts to shine.

michael_15

Not yet convinced

In theory, the uninsulated pipe also has cold air around it. The difference, at least, from a cursory thought-overview, is that the uninsulated pipe heats up that cold air and the cold air moves away, bringing in a new batch of cold air. Thus, the insulated pipe should still heat faster, one would imagine. Similarly, a covered (insulated) pot of cool water boils faster than an uncovered (uninsulated) one. (Of course, there is more going on there with condensation and all. But the same analogy holds if you're heating a pot of oil for deep-frying or what not.)

Perhaps there's just preferential steam movement due to factors we can't necessarily. For example, on my boiler, I use both tappings for risers to the header, but one of them gets hot about two minutes before the other.

-Michael

Steamhead (in transit)

Tom, that's wonderful

BTW, I saw the same effect on that Calvert Court job. With all that cold metal the first steam-up took longer, but it was still warm after we had had it shut down for a couple hours fine-tuning the vents. So the next start-up was lightning-fast.

I think you'll want some larger vent runout connections. We used 1-inch for up to four Gorton #2 vents apiece and 3/4-inch for one or two #2 vents. It's too easy to exceed the capacity of a 1/2" or 3/4" connection when using #2 vents on larger systems. That's where the welder came in handy!

If I remember correctly, the wide-open main was the one that came down into the basement on the side opposite the return line. It would make sense, if you add more vents to that main, to add them where the main drops into the basement so the steam won't have to go all the way over to the return line to close the vents.

thfurnitureguy_4

Like all things, there is perfect, and good enough this year! (or so my wife tells me). I saw pressure for the first time this year. At last the thing is acting like its designed. I hope to add insulation to the mains as the winter progresses. I also will add another 2 Gortons to what was the fast side it only has 4. There is room to run a 1" T off the top of the mains. My insulation needs to progress slowly as the boiler is still over sized. I was able to add 3 good sized radiators to the show room. and 1 more to switch out if I can find a better solution to my lefthand thread bushing Issue. I thought about brazing a 1.5 to 1.25 bushing into the left hand hole. What do you think? I think the answer to the fast heat up on the uninsulated side of the system, is that the two sides compeat for steam from the header. Both sides blow about the same at the main vents at first start. I observed that as the steam progresses the uncovered side keeps blowing and the covered side all but stops. I believe the uncovered pipe is drawing a partial vacume which becomes more evident as the steam progresses. Remember it will stay colder, even once filled with steam, then the covered pipe. It took a few late evenings spinning pipe but the results so far, are good!