Different kind of hot water system

Prisco Panza_2

Went to visit a job today . Have never seen anyting like it before. It is a complex of apartment buildings built in the late 1960's . They simply ran a 2" steel pipe main around the perimeter of the building. They welded 1" nipples into the main feeding each apartment . There is a stop valve and a 1" zone valve right after the welded nipple. The main continues around the building and in the middle of the system there is a 2" gate valve, after the valve the main continues around the perimeter of the building and back to the boiler. How does the water get up into the radiation? No one pipe tees at all in the system. It is very odd . It looks like they were very, very frugal while constructing these buildings. They want to replace the boilers and pumps in all of these buildings. Eight out of 9 buildings heeat well and one does no. Any ideas?

Prisco panza

Tom M.

a couple thoughts.

Are there tees after the 2" gate valve? Is it possible that the apartments are supplied from one side and return to the other side? If this were the case, the 2" gate valve can probably be throttled down to increase the pressure differential between the supply and return or be opened more in warmer weather when the zone valves will be closed more of the time. Maybe the gate valve is open too much in the building that doesn't heat well.

If you could get access to one of the apartments and turn up the tstat, you could see how fast things heat up and get a better idea of how the piping is arranged.

jeff_51

you sure it isn't a mon-flow system?