Steam problem ( long story )

Unknown

In hindsight , we should have used a shorter boiler . We reconnected the short 2 inch main 1st , then ran a 2 inch pipe to a small main we made to accomodate 3 radiator pipes . The last tee on the boiler main connects to another tee - this tee had a single rad connected to it which runs horizontally to the left . The top of this tee connects to an 1 1/2 inch main that goes through a crawspace . This is where our problem is . The connection is in the pic " problem pipe " , the rusty one , top right going through the back wall .

There are 2 rads that connect to this problem main . One is on the 1st floor , one is on the 2nd . The homeowner complained that neither one got hot , so we went back there and fiddled around , repiped the dry return to bring the end up a litle while keeping a proper pitch . Still , the end of the dry return was right at 28 inches from the water line .

A few weeks later we get the same complaint . My supervisor and a fellow installer go back to see whats up . They disconnect the dry return on the problem side right where it drops down from the main and notice water backing up almost to the top of the return pipe while the boiler is steaming - no pressure though . After observing this , they believe the problem might be water backing up from the return into the boiler main and choking off steam flow into that problem steam main . So they went back yesterday to repipe the boiler main higher , and took out the drop . I came later to help . We raised it a good 6 inches or so , giving us maybe 28 inches from the water line to the boiler main . We also increased the pipe size to 2 1/2 inch , and disconnected the one radiator pipe connected to the problem main near the boiler . We reconnected that radiator pipe to the new main I made on the left of the boiler .

We let it steam - all the mains near the boiler supply get hot at almost the same time . The problem main gets hot too - as far as I can touch it through the 1st crawlspace it goes through , maybe 3 feet from the boiler main . All the rads get hot too - except the 2 rads on the problem main , again ! We feel the dry return as far as we can into the crawl - ice cold for a long time . We pull the main vent on that side and stuck a latex glove on the hole to see what's going on . It blows up part way then sucks in - on and off , on and off . We pulled the vent on the 1st floor rad and had the same panting . About 20 minutes after all the other rads got hot , we finally got some steam out of the open main vent hole .

I didn't go in the crawl space , but the supervisor who did said the pipe is pitched down all the way to the boiler room . It does decrease in size from 1 1/2 to 1 1/4 somewhere in the crawl , and some insulation is missing off the pipe . It's about 20 foot total run , making about 3 turns before it come back to the boiler . 1/2 of it is laying right on top of the dirt .

Does anyone think the 1st 2 tees on the main can let so much steam to their rads that it'll choke off flow to the last tee ? Or does anyone think the panting has something to do with the pipe in the crawl ? Maybe a partial block somewhere ? Maybe the dirt is robbing all the btus from the pipe ? Can a sag in the horizontal pipe make a water seal ?

Thanks for any help in advance , we're at our wits end on this one . It woulda been easier to convert the house to baseboard , I hate saying that .

Unknown

To start this right

I have to include a few pics of the boiler we replaced , and how badly a steamer can be piped and still function . This was in November . There were 4 pipes that went directly from the top of the boiler to their radiators . The condensate ran right back into the boiler from the top . There was also a 2 inch and an 1 1/2 inch main , both had dry returns .