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Should this pipe be hot?

nz Member Posts: 125
So, I'm about 1/3 of the way through my trap replacement project. As I've become more intimately familiar with my system, I came across a pipe that I'm not sure if it should be steam-hot or not.

It is a horizontal line coming into a vertical pipe that connects the wet return, and a dry return - there is a crossover trap between the vertical pipe and the dry (horizontal) return.

The horizontal pipe - I'm unsure of its source (it's coming out of a wall, the other side is covered), can't tell if its meant to be a drip from the steam supply lines to the radiators on that side of the house (in which case it should be hot)...or if its a dry return that shouldn't be steam-hot. It gets to 210 degrees or so.

The house was built in 1930, it's a Dunham vapor system.

Please see pictures below.


  • gerry gill
    gerry gill Member Posts: 3,078
    i believe

    that is the end of a steam main since it has a crossover trap that discharges to the dry return..if i understand your description and pictures correctly.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • nz
    nz Member Posts: 125
    Steam Main

    Would the steam main loop around? The main is on the left (insulated)...and stops before it hits the wall, and curves down into the wet return. Before the end, there are two takeoffs which service different radiators in sections of the house.

    So - the "hot pipe" is coming out of the wall right where that arrow is labeled "hot pipe" - from the opposite side of the house (from where I took the picture, the boiler is behind me in another room) I'm puzzled...
  • Steamhead
    Steamhead Member Posts: 16,727
    That's correct

    one of those takeoffs goes to the other side of the wall, to feed more rads- there's probably a crawl space back there- then comes out and vents thru the crossover trap. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    End of Steam Main drops and vents

    I am guessing for the parts that I can't see... on the other side of the wall. But first, the insulated pipe as you have stated is the end of one of the steam mains.  It is sloping down as it travels from the boiler, so as it comes past the last radiator take offs, there should be a crossover trap to vent it to the dry condensate return piping and also, a drip leg that drops to below the water line.  I suspect that the hot pipe that is coming through the wall is the end of the other steam main the loops around the other way.  It too should have a crossover trap, perhaps that is the one that we can see, and it would drop to the wet return, and that is the pipe that you say is hot.  Makes sense that it would be hot, if it is the end of the steam main.  Why one is insulated and one is not is a good question .  Perhaps the uninsulated one is so close to the wall that there was not enough room.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • nz
    nz Member Posts: 125
    Makes sense

    I wasn't quite sure, because there is a similar set up in my basement bar bathroom, but no pipe coming out of the wall - the main just has a 1/2" line going into a crossover trap. I just wanted to make sure I didn't have some wide-open secret trap that was buried in the plaster ceilings in the basement room behind that wall.

    That room behind that wall and one floor above is the living room, and has three in-wall convectors, and the bedroom above it has 3 cast iron tube rads.

    Thanks for the feedback, I won't worry about it.
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