Where to Put main vent ?

G_thehelpernyc

I have a 10 unit 5 floors apt building  in bronx. one pipe steam with 2 mains 2.5 inch serving 3 2 inch risers each. I currently don’t have main vents on the mains and looking to install a Gorton 2. The mains run 30 ft from the boiler to end of main. I am having issues with heating not reaching the last floors. These are picture of both ends of mains

neilc

this last picture shows a "main" atop that left most tee,
is there another in those back dark shadows ?
this main is too small,
I see a bushing, which when removed, could fit a larger vent,
what's in the shadows?

neilc

and have you looked at the tops of those risers?
could / should be vents up there,

Mad Dog_2

Could be a puddle, but when you have plenty of Steam Available its going to blast in to the puddle & past it toward the point of lower pressure, the rad or main vent.  Mad Dog 🐕 

Jamie Hall

neilc said:

and have you looked at the tops of those risers?
could / should be vents up there,

This. If you can put some good big main vents at the tops of the risers, you almost certainly will see an improvement.

EBEBRATT-Ed

You may need to drill and tap to put vents on. You probably could use vents on the tops of the risers as well. Probably was designed for coal originally so it probably had few if any vents.

If you could post a sketch of the piping in the picture and mark where the pipes go it would be easier to decide where to put the vents.

G_thehelpernyc

So each side the building has 3 riser coming off the main. One 2 inch for the bathrooms running straight up . Another running straight through the bedrooms and suppying a radiator on other side of wall in kitchen. The third riser runs straight up Also straight pipe on one side and supply radiator on other side of wall. The 2 riser are exposed on the last floors and have Gorton D radiator vents tapped on the pipe. The 3rd riser on the last floor changes instead being straight pipe in bedroom is instead supplying 2 radiator back to back rooms

G_thehelpernyc

Jamie Hall

The Gorton D is a nice vent. It's not a main vent. Swap them out for Gorton #2s on the risers (not on the radiators -- leave the radiator vents alone to control the radiators).

dabrakeman

Looks like the main in your first pictire is setup parallel flow with an existing main vent at end of the main extension.  Easy enough to increase that venting but that only addresses 30 ft in a 5 story building.  The other main probably would require drill and tap.  As @nelic and @Jamie say biggest improvement would be if can get main vents at the top of the risers.