Main is piped directly into the return

AlexT

I have a one-pipe steam system in my house. It mostly works well, but when they replaced the boiler they did something wrong. There are two branches coming off the main, one plumbed as a main with a loop generating condensate and eventually feeding into the return and into the boiler again. The other branch has the condensate drain into a pipe which directly feeds into the main air vent. The problem with this is that as soon as a little steam is generated the main air vent immediately closes, and the all the air noisily gets pushed out through the radiators.

I'd like to fix the issue with the way it's piped so I have a main vent that actually does something. The options to fix it are to either 1) have the branch condensate separately drain into the return or 2) just remove the condensate drip line entirely.

Image is attached, hope this makes sense. Thanks for any advice you can lend.

Steamhead

Someone tried to vent both mains with just one vent. That's wrong. The drips (drains) from both mains need to drop below the boiler's water line before tying together, and each main needs its own vent.

How long are your steam mains, and what pipe size are they?

AlexT

Steamhead,

Thanks for the response.

The mains are 2" pipe. The incorrect drip is 1". The main that services most of the radiators is 20' long including the loop back to the water line. The other main runs 13' in the basement plus another two stories up to the 3rd floor where there are three radiators. There's not a lot of room to add a vent to the 13' run, though I could probably find a way to get one there.