Fixing two pipe system

ordellrobbie

I am working on fixing a two pipe system. There is a lot wrong with it. There is steam in the returns very soon after it starts making steam. Some radiators were added and traps were never installed on them but there is also steam coming back through a pipe that comes off the header and ties directly into the return. The only original radiators are on the second floor. They all have traps but they also have vents. The vents look like they were added at some point because they are in the top corners rather than where they’re supposed to be. I know I need to add traps to the radiators that don’t have them. I need to add a lot more venting. I think I need to get rid of the radiator vents. I’m not sure what to do at the end of the mains. They’re definitely not original. There are two mains and two dry returns. They took the ends of the two mains and tied them in together and ran a 3/4 drip to one of the dry returns with no trap. I can’t figure out what it originally did. I don’t see any evidence that they went to wet returns. Maybe the connected to the dry returns through traps? There are crossover traps that look original. Would they have needed the crossover traps if the mains tied into the dry returns through traps? What they originally did I guess is less important than what I need to do with them now which I can’t figure out. I’ve attached pictures of the ends of the mains and near boiler piping. I am thinking maybe there was a boiler return trap that was removed at some point and they thought they needed to tie the header into the dry return. I’ve attached a picture of this and I am planning to get rid of that pipe. I’ll also add a vaporstat. I also have a video of the whole system but I don’t know how to post it. Thanks 

Jamie Hall

Your best solution to the ends of the mains and the dry returns is also going to be the simplest: Make those copper lines connecting the two into water seals by running them all the way down to the floor and then back up. Then if there is a crossover trap, make sure it is piped right: it should go from the top of the main, up a few inches, over 90 and to the inlet of the trap, and then straight down from there to the return. If they aren't set up that way, it may take some ingenuity to install them. Then provide copious main venting on the dry returns at the boiler.

You could also add main vents at the ends of the returns, but that will take as much effort as a crossover -- and have much less venting capacity unless you use several big vents.

It would be much better to separate the two mains and treat them individually.

Make sure the dry returns pitch towards the boiler, since you don't have wet returns.

Now add traps to the radiators that don't have them. You can leave the vents on them -- they won't hurt anything, though they won't do much either. Or take them off...

Now since you will have water seals, maximum operating pressure becomes important. If there is enough height in the water seals, you could get away with a cutout of 1.5 psi, but that would require at least 42 inches height and 84 inches would be a lot better. I'd use a vapourstat cutting out at 1 psi max.

ordellrobbie

Thanks Jamie, I would install the loop seals at the ends of the mains and then come back up and tie them into the dry returns? I plan to separate the mains if we repipe the boiler. 

mattmia2

I'm guessing someone didn't like the wet returns on the floor a couple boilers ago and removed them incorrectly. Which way do the dry returns slope now?

ordellrobbie

They pitch mostly towards the boiler. There are some spots that are level or slightly back pitched. 

Erin Holohan Haskell

@ordellrobbie, you can post your video on YouTube and share it here. Thanks!