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Open pipe venting on 2 pipe dry return??

JUGHNEJUGHNE Member Posts: 7,861
I am redirecting 2 dry return drops from the gravity wet return into the condensate pump. These 2 returns have no place to vent air and compete with the pump discharge that goes into the wet return also. Then all return condensate will go thru the cond pump.

I thought that in the boiler room I would add open vent pipes above these returns. The top of the vents would be well above the horizontal dry returns. I believe this would give quicker venting that going thru the cond pump and give an indicator as to which of the 3 returns have the bad traps that are passing the steam out of the cond pump existing vent pipe. There are about 45 rad traps and 11 F&T traps scattered though 7 different levels of building, so narrowing down which return is the culprit would help reduce footsteps.

Does anyone see any pitfalls to this plan? There would be ball valves at the top of the open vents to close off if needed.


  • Jamie HallJamie Hall Member Posts: 14,757
    Nothing like a hybrid system to create interesting problems, eh? No, I don't see a problem -- other than if there is or are bad traps on one of those returns, you will get steam in the boiler room! Sounds like a hands on operation...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ChrisJChrisJ Member Posts: 11,476

    Nothing like a hybrid system to create interesting problems, eh? No, I don't see a problem -- other than if there is or are bad traps on one of those returns, you will get steam in the boiler room! Sounds like a hands on operation...

    You mean just like if a main vent fails?
    Or a radiator vent, for that matter?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNEJUGHNE Member Posts: 7,861
    Yes, anything like that can fail. There are 4 G-2 vents before a new F&T on the busiest Line. Those flood and spew water on occasion because of that return not draining correctly, however they are in a shower room with good floor drains.

    The cond pump is vent up and over to a sump pit in the boiler and steam will blast out sometimes. Not noticed always, but has done enough damage to erode the inside corner of the wall, evidence that this has gone on for years.

    Thanks for checking in on this, any other comments are welcome.
  • JUGHNEJUGHNE Member Posts: 7,861
    So this weekend the 2 dry returns were separated from their horizontal connection, their check valve removed and both connected to the condensate pump inlet.
    This re-piping was done with some copper, black pipe and if you look closely there may be a galvanized fitting lurking there also. (Also most of it is used from other change outs, will bill accordingly)
    Yes, against most steamer rules, but building has a limited life span and this old guy wanted to thin out his shop collection, also my 1 1/2 pipe threader does not have a cord on it. ;)

    Most water hammer is gone, boiler water level stays near center of glass. (previously would run out of water, LWCO would add and then boiler would flood above top of sight glass when water did eventually return, then refire and throw water out and run out again. It must have cycled like this for many years.
    The black pipe open vent is on the busiest return with a new F&T.
    The copper pipe still has an original Webster F&T that may get replaced. The mirror fogs on this one.
    The double 90 vent was added for the cond pump.

    The cond pump vent discharge goes over to the sump pit.
    There are pictures of what some years of blowing steam into that corner has done.

    There are 3 G-2 main vents on the larger main just ahead of the new F&T. They used to pass water all over the floor as the main would get flooded. They are now behaving for the last 2 days anyway.

    A 2" strainer was added on inlet of pump. The pump seems to have the capacity to handle the entire 3839 EDR.

    Just a note on longevity, part of the wet return is from 1938 and still has plenty of meat left in it. A new 3 1/2" main, welded pipe has a seeping leak in the bottom of the pipe, this is from maybe 20-30 years ago.

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