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Main valve in wrong place?

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mene
mene Member Posts: 4
Hi! Everything I read has the main valve “at the end” of the steam main. My system (single pipe, 1 family house) has the main valve roughly 10 feet after it goes from main to return. I will try to add a drawing to clarify. There are also several plugs along the way in the steam main. This makes me think maybe they should not be plugs but valves instead? If nothing else, should I move the main valve to the end of the main; replacing a plug that’s there, and plug the return valve instead?

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  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,004
    edited March 31
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    I think you mean the main vent. 

    I’d leave it where it is. 
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    EdTheHeaterManbburd
  • Jamie Hall
    Jamie Hall Member Posts: 23,322
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    Nothing wrong with that setup.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • mene
    mene Member Posts: 4
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    Ouch, yes of course, main vent not valve. Thank you both for the help! 
  • RTW
    RTW Member Posts: 60
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    I have the identical set-up with vent placed at end of dry return into wet return as in your diagram. I believe its placement is critical ( I believe there is an explanation I have read about, but Im not qualified to answer why). The only difference in my single pipe steam is I added a Main Vent at the end of the Main where it empties into dry return ( the last plug in diagram). Notwithstanding, I would follow advice from pros here. Regards RTW
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    edited April 1
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    RTW said:

    I have the identical set-up with vent placed at end of dry return into wet return as in your diagram. I believe its placement is critical ( I believe there is an explanation I have read about, but Im not qualified to answer why). The only difference in my single pipe steam is I added a Main Vent at the end of the Main where it empties into dry return ( the last plug in diagram). Notwithstanding, I would follow advice from pros here. Regards RTW

    This may be a good idea. But the location of that plug may not be an ideal placement for a vent. It also may be fine.

    You should not place a vent on a run of a tee. It should always be on the branch of a tee and not near an elbow.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • RTW
    RTW Member Posts: 60
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    BY ED; This may be a good idea. But the location of that plug may not be an ideal placement for a vent. It also may be fine.

    You should not place a vent on a run of a tee. It should always be on the branch of a tee and not near an elbow

    BY RTW:
    Just to follow up, I inherited the "incorrect" example that has a Dole vent on dry return about five feet from boiler location that drains into a wet return (seems to work). The height is about 24 inches above the water line that I read somewhere is critical. However, the Main vent at the end of the Main is like the "correct" example and on an antler but goes into a horizontal dry return, Not straight down. Appreciate the diagram