2 pipe vapor system?

Paul S_3

Hey guys. Does anyone know what the large cylinder is.  Boiler return trap or differential loop? I'm guessing the system is probably a vapor system. The large pipe at the bottom goes into the bull of a tee with check valves on both sides of the run of that tee. The small pipe on top from what I can see goes into the chimney. Radiators all have traps. Customer has a bunch of radiators that never heat that no one can fix. I can't find it in Dan's steam book. Just trying to be prepared when I go back.

Davidho

That looks like same trane system I have. I don’t have a pipe going into chimney. Main goes maybe 2 feet past the return main than drops straight down. Where there is a U made connecting to a one way flapper valve than trap than flapper. I am only a homeowner.  From what I understand that boiler return trap was used before vaporstats. I didn’t know what was going on until I got an ounce gauge on the boiler.

Jamie Hall

Vapour system -- Trane, I think. The pipe into the chimney is the main vent for the entire system.

Not too many ways these can go wrong.

First, pressure -- must be maintained below 8 OUNCES per square inch -- which pretty well means a Vaporstat, not a Pressuretrol for the boiler (you can keep the pressuretrol and use it as a safety backup)(you'll probably want to add a low pressure gauge -- the code required 0 to 30 psi gauge is useless).

Second, traps. There should be crossover traps at the end of each steam main leading into the corresponding dry return. Make sure they are working, or if some brilliant child replaced them with main vents make sure those are working. There should also be a drop to a wet return at the same location -- and one from the steam main -- unless both pitch back to the boiler, which is unlikely.

Third, pipe pitch. Make sure that all the elevated pipes -- mains and returns both -- pitch to drain to a wet return or back to the boiler. Most likely a wet return. No sags. No reverse pitch.

Fourth, radiator valves. They can be open or partly closed to control the radiator. If a radiator isn't working... I know it sounds silly, but make sure the valve is open.

Fifth, radiator traps. A failed closed trap will prevent the associated radiator from heating. A failed open trap will allow that radiator to heat -- but may and often will prevent other radiators on that return from heating.

Steamhead

@Paul S_3 , @Davidho and @Jamie Hall are correct- this is a Trane Vapor system. We see a lot of these in Baltimore. The cylinder is a Direct Return Trap. Go here for more:

https://www.heatinghelp.com/systems-help-center/trane-heating-specialties-for-vapor-and-vacuum-systems/

Most Trane systems used standard air vents on the steam mains and dry returns. If one of these is not working, the radiators it serves may not heat. Check this first.

delcrossv

According to the image in the link, the small pipe is to the dry return (?)

EBEBRATT-Ed

If the pipe vents in the chimney it may be full of soot, and if traps go bad your sending steam into the chimney which is not good and it may not be noticed. I would put a large vent on it

Paul S_3

@delcrossv you may be right according to the literature I read. 

Jamie Hall

EBEBRATT-Ed said:

If the pipe vents in the chimney it may be full of soot, and if traps go bad your sending steam into the chimney which is not good and it may not be noticed. I would put a large vent on it

So would I. A Gorton #2 to start with, and see how the pressure holds.

Mad Dog_2

Frank. .Broomells also vent in to the chimney, right?  Mad Dog 🐕 

Steamhead

Mad Dog_2 said:

Frank. .Broomells also vent in to the chimney, right?  Mad Dog 🐕 

Yes they did. As did VECO and others. But a Return Trap would not.

Paul S_3

Is there a possibility the boiler return trap can fail?