KIN10 Conversion - Need Help on Main Vent Valve Sizing

IN10Steam

About two years ago I bought an old 1940 home with the original steam system (coal converted to oil),
and recently converted to natural gas steam heat. The system has been very dirty and noisy, installer blamed it on old vent valves. I figured out they had to much pressure running through my system so reducing it has helped but all my vent valves were changed with cheap home depot maid-o-mist ones and I would like to begin to install the proper gorton valves.
My question is on the main lines what would you recommend for the proper venting?

Line 1: 20' of 3" pipe then reduced to 30' of 2" pipe to the vent valve. (std no name HD 3/4" I assume)
My estimate is 1.75 (20' @.053 + 30' @.023)

Line 2 is 60' of 2" pipe to the same cheap HD vent pipe (problem here is i only have 6" from pipe to ceiling and the current HD valve is 3" tall so I am not sure I can build an antler or extend much)
My estimate 1.38 (60' @.023) Gorton #1 due to space?

I apologize in advance for the newbie and maybe redundant question but I was unable to verify the proper calculations for 3" pipe. Thank you in advance for your help.

Steamhead

What kind of ceiling is above that vent? Unless it's concrete, I'd just make a nice neat hole and put a Gorton #2 on it. Or, add some elbows and nipples to get it past an obstruction. We do that all the time.

I'd put both a Gorton #2 and a #1 on the longer main.

IN10Steam

The ceiling above is plaster and the gas line is also attached in that area. I will try an take a picture later tonight. Would it be wrong to install the #2 if it fits directly to that elbow that returns down (drops approx 4 ft to return to the boiler)?

As for the larger main I have the space to build as you suggest.
Right now it appears when my heat is on there is still to much pressure in my system as the radiators teapot towards the end of the line. Hoping the fast venting will correct and I can balance the radiators with proper solid valves.

Thank you for your feedback.

nicholas bonham-carter

As a rule of thumb, we say that one Gorton #2 for each 20 ft. of 2 in. pipe, so you probably need several on each.
If you have a good low-pressure gauge, then you can see the resistance (backpressure) of the escaping air. The air should escape during the venting phase at less than 2 oz.
This coupled with slower radiator vents, will fill all the mains with steam first, and then the takeoffs to the rads next, delivering steam to all the rads simultaneously.—NBC

IN10Steam

Attached is the 2" main line ending with the vent valve with clearance issues. If I can't open the ceiling above can I use an elbow,nipple and some T's to install (2) Gorton #1?
What type of piping should be used?

IN10Steam

Close up, valve measures 3" tall, 6" from elbow to ceiling