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What is this thing?

Housedoc Member Posts: 66
Greetings from the snowy south. I am working on a 2 story home that was built in 1948. The home incorporated radiant heating in the ceilings of both the first and second floors. The basement includes radiant in the concrete slab. Originally, the boiler was oil fired and eventually converted to gas.

I climbed up in the attic and found lots of copper pipes as well as the device attached hereto. An 1-1/4" copper main runs up through interior walls to the middle of the attic. It connects to the bottom of this black device. Then a second 1-1/4" tap comes out of the bottom right beside it. It elbows back and then tees with 1 inch running to each side of the attic. Each leg of this main then accepts multiple tees coming directly out of the ceiling. Each radiant circuit includes a circuit setter and a manual air vent.

It turns out the 1-1/4" riser is connected directly to the return on the boiler via the circulator inlet. IN other words, every bit of the apparatus in the attic is on the return. I am suspicious the supplies tee off in the basement and route up two to the ceilings on both the first and second floors.

Has anyone seen one of these things before. It is NOT an expansion tank. Its down in the boiler room.


  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    It could be

    somebodies ingenious device to remove air from the system for initial purging. If that is the case the little copper tube probably ran back down somewhere you could watch it. Once water started coming out, the system was full.

    I dunno?

  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    Air vent

    This was a common method of air removal before "pumping away" became popular. It doesn't work very well after the vent becomes clogged or fails. Vet is also subject to freezing. Better purge methods happen at the boiler and also use an air eliminator with proper "near-boiler" piping.
  • Weezbo
    Weezbo Member Posts: 6,232
    do me one small favor and have the guy

    insulate the pipes and get some insulation in the attic , that's waaaaay to expensive to live with like that..

  • Housedoc
    Housedoc Member Posts: 66
    Good news

    The good news is, we are replacing the boiler and have the opportunity to eliminate this device. We are also encapsulating the attic with spray foam. So the entire attic will soon be inside the thermal envelope. We've found on most cold days, the attic is within 3 to 4 degrees of the conditioned space temperature.

    So the consensus is, this device is quasi "wanna be" Spriovent, most likely without the inside guts. Or just a big bucket at the highest point in the system to gather air.

    Now I need to find the supply branches to the second floor ceiling radiant. Was it customary in the late 40's to run a supply trunk in between floors and route supply branches up to the ceiling of the 2nd floor from the joist space between or has anyone seen tees and supply branch run all the way from the basement to the 2nd floor ceilings? The first floor ceilings are routed from the basement and each circuit has a gate valve. If the second floor ceilings are fed from the space between the floors, there may be gate valves but there sure isn't any way to access them.
  • Housedoc
    Housedoc Member Posts: 66
    More Info

    Upon further sleuthing, I've discovered that all the piping in the attic is on the return side of the system. In other words, the first floor ceiling radiant panels are all routed up into the attic just like the second floor ceiling panels. If you want to bleed the air from the 2 circuits in the first floor living room or dining room ceilings, you have to climb into the attic and open the respective manual air vents. The the mystery black thing must simply be a large air eliminator. Its about 2 ft above the top of the entire system.