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2 pipe crossover trap or air vents ?

clammyclammy Posts: 2,063Member
Having to possibly re do a decent portion of a 2 pipe steam over including dry returns which route would you go. A bunch of vents on the main and dry return before the drip w a decent water seal or would you forego the main vents on the steam main and use a crossover trap into your dry return and vent the living crap out of it. In this situation the most possible positive outcome would be that the rads basically see steam only after the crossover trap is closed which I would think would be when radiator would start venting. The other way which would be vents both main n return may end having rads on the beginning of the main would be served first. This is a perimeter main n return starting in the boiler room n from what I can imagine at one time ended near the boiler room. Issue is someone but he’d up the last leg of the system install a f n t trap. Discharging into some crazy sort of knuckleheaded return piping it’s all garbage n I know what needs to be done$$$ but the crossover trap over a vent supply has me leaning. So what’s the gang have to say. On a side note it s 2 pipe 100 year old on who knows what # boiler total hack a piping only stuff the good is the original piping on parts of the system bout 45 ft the rest is knuckle headed most of the traps have never been touched can’t tell after over a 1 hr firing what’s good what’s bad because the mains don’t get that hot being there’s no insulation n the boiler is not even close to manafactures specs aside from all the great stuff how about the original thought. Peace n good luck clammy

Comments

  • Jamie HallJamie Hall Posts: 8,945Member
    I'd go with crossover traps and vent the dickens out of the return(s) at the boiler. But that's my preference -- I think mostly in terms of the various "vapour" systems, which almost all do that.

    Then the ends of the mains and the dry returns both go down as drips to a wet return with a water seal. Which, of course, can get messed up if a knucklehead lowers the boiler water line -- but you wouldn't do that!

    You still won't get simultaneous steam at all the radiators, particularly on longer mains -- there just isn't any way to do that. But it's astonishing how close you can come.
    Jamie



    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
  • EBEBRATT-EdEBEBRATT-Ed Posts: 4,499Member
    So many times I see jobs that you take a look at it and you can tell originally a decent job the it gets all botched up by people that know nothing.

    I am assuming this is gravity return. I would thing crossovers would vent the main faster and get the steam moving faster. Then big mouths on the dry returns.

    You mentioned radiator venting, but it's two pipe so I am confused about that.

    Sounds like you got your hands full on this one. Your head spins around and don't know where to start. Same way you eat an elephant, one bite at a time. Easier said than done!!

    Good luck. Good to here from you Clammy!!
  • clammyclammy Posts: 2,063Member
    Thanks for the support I was leaning towards the cross over as for rads venting I mean air being dispelled from the radiator into the dry returns not a vented radiator which in this case a few where added here n there by others in a attempt but futile in getting heat to those rads but enough to get some to one or two others it’s totally amazing because aside from absolutely no main or return vents at all it manages to produce some heat again here n there I believe aside from the few radiator vents Band aided at a few rads it would be air bound. It has a cycle guard which masks a whole lotta hubbub They had a few others look who shook head n left peace and good luck clammy
  • EBEBRATT-EdEBEBRATT-Ed Posts: 4,499Member
    I am sure you will be able to slog through it successfully!
  • gennadygennady Posts: 709Member
    edited December 7
    Is this HOFFMANN controlled heat ? It has differential loop shutting down main air vent. So I would go with crossover trap in this case. I had a case with flooded return , I had to go with master vents instead, but it was 100 year old installer mistake.
    Gennady Tsakh



    Absolute Mechanical Co. Inc.

    www.AbsoluteMechanicalCoInc.com
  • clammyclammy Posts: 2,063Member
    It has a mix of sarco and Dunham radiator traps the inlet valves may be sarco can’t really tell so much paint vapor style supply valves as for any renaments of differential loop or return trap are long gone one of two things I do know it’s got rad traps and it has no ,main or dry return venting There isn’t even signs of the original coal damper pulleies usually in older homes. I see them. Nothing here it all just needs some tlc repairs and of course what makes it all happen $ until that nothing changes. Peace and good luck clammy
  • Jamie HallJamie Hall Posts: 8,945Member
    When you finally get going on it, @clammy , my own feeling -- admittedly biased -- is that you will be happiest with crossover traps and copious venting on the dry returns at the boiler. Then turn the pressure down -- way down -- and use a vapourstat with a cutout at perhaps 8 to 12 ounces (since there isn't a differential loop, you can go above 8!)(but not that much above -- not needed).
    Jamie



    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
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