Old boiler system - need some educated opinions

Carleton Hecht

I have a customer working on a boiler system in a 5-story building (built in 1911) in Chicago. It's a downfeed system with a 7-inch express riser to the top floor that splits into 10 downfeed pipes that feed all the one-pipe radiators on floors 2 - 5. The 1st floor radiators are 2-pipe radiators, but no traps - just two valves. Maybe one valve has an orifice??? The supply & return for these disappear under the floor. There is one of the downfeed pipes from the upper floors near each first floor radiator that also disappears under the floor. I thought maybe the first floor radiation is fed by those pipes also, but there are two returns coming from, and one main going to the area we can't get to.
I'm looking for an educated guess on how those first floor radiators get their steam - from the downfeed pipes, or the main disappearing through the wall?
The bottom line is - my customer needs to disconnect all the radiation from the top 4 floors, and the easiest way would be to cap the express off. His customer doesn't want to heat those floors - it's only used for storage & there is no plumbing to worry about. But, we can't figure out how the first floor gets it's steam. Any guesses?
The original boiler was a 2.9 million HB Smith, and the new boiler is a Peerless 211-7. The new boiler is plenty big enough to heat the first floor, with 2 sections to spare. My customer oversized it to compensate for the big piping system. But, the boiler has to heat up the entire piping system, which costs his customer money - he'd love to be able to cap the express.
Also - the mains are dripped - probably because the express is offset about 20 feet from the header. There is no F&T trap on the drip - shouldn't it have one?
Please give me some opinions on this system!!

Ben_3

Carlton

Do the radaitors on the first floor have air vents as well.
What is the area you can't get to? Does the one main branch off the header in add. to the express main. Do the two returns have air vents on them? More info on the piping and rads and we might be able to figure it out. As for the drips if the exprees main offsets more than acouple of feet you should drip it to a wet return with 2" pipe for an 8" main or with a F/T trap 1 1/4" for 8"main.
Also if your returns are way oversised and piping oversized the system will be slow to heat w/o really good venting and insul. and the returning condensate will be very slow to make it back and could result in flooding of boiler.

Carleton Hecht

Thanks for your input - here is what we can see...
Most of the radiators on the first floor are in the front of the building, over a crawlspace that is blocked off. (don't ask me what they will do if they spring a leak!!!) The two-pipe radiators on the first floor all have air vents, as do all the returns (main line vents) back to the boiler. The steam main that disappears through the wall branches off the header opposite of the express riser. The few first floor radiators we can see from the basement are fed by that main, and all return to the same return pipe. We can also see a couple of the downfeed pipes coming down from the upper floors - and they all tie into the other return pipe coming through the wall we can't get behind. If we could determine that all the first floor radiation is fed by the main opposite the express, we could kill the express & make the system much smaller. You are absolutely correct - he has a overfilling problem, but he predicted that, and quoted his customer a boiler feed system on his boiler quote, and explained there was a good chance they would need it. But if we can cap off the express, that would take out over 60% off the system piping, and may stop the overfilling problem.

Ben_3

Carlton

Judging by this info I would say your first floor rads are from that one main. However I can still see a lot of potential probs. The one return you see that doesn't tie into ant first floor rads. should only be for the downfeed system. The reason I say this is because of pitch. In a downfeed system the steam and condensate are flowing the same way and the pitch doesn't have to be as great as it would in a counterflow system. The first floor however you said is over a crawlspace. They probably didn't have enough space to get back to the boiler as a counterflow system due to pitch and the same probably applied when they looked into making it an uplow parallel feed as well for the first floor system. With only one pipe on each radaitor the main would have to run the perimeter all the way pitching back to the boiler again maybe not enough height. So they ran a one main and one return probably by splitting the length was shorter and the pitch wouldn't be a problem. But this would have been very difficult to control, you see there is nothing to keep the steam from entering the return and stopping the heat and the returning condensate. If the main is higher than that return it's possible that the returns would have been below the orig. boilers water line and this would not have been a problem. With a new boiler {and a new lower water line} they would no longer be "wet". Let the banging begin! If your contractor has already priced for a boiler feed pump you could possibly install traps on the first floor rads. and plug the air vent holes. You then can cap off the express and express return and drip your main to the pump with a F/T trap. As long as that main and return the rad traps would drain to arn't connected. The main probably isn't connected to it if it looks like I'ts pitching towards the boiler. You have a perfectly running 2 pipe system now and no more leaking vents. In fact the feed pump's vent line would act as your vent, But NEVER put an actual vent on this line. MIght just work if all the conditions are right.
P.S. If I can be some more help E-mail me I also live in Chicago.

Carleton Hecht

Thanks for your input! I'll let you know how this job goes!