Radiator Not Heating, Pipe Gurgling

Hedwig595 · January 13

I’m continuing the adventure with my 1920s 2 pipe Warren Webster Sylphon Modulation system and I have one last radiator not heating.

I replaced the trap, no luck, pulled off the valve which is in great shape and heard gurgling coming from the feed pipe while the boiler was running.

This rad is in the 3rd floor finished attic which has three other rads that heat well. I looked in the basement, basically trying to follow the feed pipe straight down as it is near the stairs, and found the main header terminates and then shoots straight up, so I’m wondering if the mains might be pitched incorrectly and there’s a slug of water in there?

I should also note, about 20’ of header in the basement is uninsulated (the rest has that wrap which I assume is asbestos). I’m planning to insulate but not sure if that alone would solve the problem?

As always I really appreciate all the help and ideas!!

Jamie Hall · January 13

It could be that that main has lost its pitch — it must pitch back to the boiler, since it doesn't have a drip.

mattmia2 · January 13

that would be worth testing. it looks like fiberglass with a paper facing but also looks like there is some possibly asbestos containing mud at the joints.

it seems more likely that there are some offsets at it works its way up that are missing pitch.

can you tell what the pitch of that piping is with a small level?

how does this system vent the mains, does it need crossover traps?

Hedwig595 · January 15

I have not found a crossover trap yet. The only vent I have been able to find is this guy (should I try to open it and clean it in the summer?):

I put a small level on the pipe and it reads as basically level so I think pitch might be an issue. What’s the best way to re-pitch? I’m thinking lever it up with a pipe/bar and then install a strap holding it up to the joist?

The main in question runs back into the boiler through this route. Could the connections with blue boxes be crossover traps or something?

Jamie Hall · January 15

The blue boxes are check valves on the wet returns. Not sure why they are there…

There is some rather creative looking plumbing there. Be interesting to go over the whole system and see how it was meant to work, and how it has been changed over the years…

mattmia2 · January 15

that drum thing is part of a vapor system of some sort. there frequently was a set of check valves on the boiler return in many vapor systems to allow it to equalize the mains and the returns

Radiator Not Heating, Pipe Gurgling

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