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Illinois Vapor System

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SteamDrew
SteamDrew Member Posts: 6
in Strictly Steam


Hi All,

We were sitting in the office today discussing 2 pipe vapor systems and I had a technical question I haven't been able to find any answers to. In the attached photo from the Illinois Vapor System manual, you can see there are 2 swing check valves in the returns, one for the Vapair trap and one for the Return trap. We are wondering, why the need for 2 check valves? My assumption would be that it is there to prevent the back pressure from when the return trap drops from affecting the Vapair trap. Any input would be greatly appreciated.

SteamyDrew
Service Manager @ Williams Stoker & Heating
Chicago, IL
Steam, Hydronics, & Mechanicals

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  • Steamhead
    Steamhead Member Posts: 16,936
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    The Return Trap is basically a pressure-powered pump, and needs a check valve before and after the "to-and-fro pipe" (goes into the bottom of the trap) to work. If you have @DanHolohan 's "The Lost Art of Steam Heating", the Return Trap operation is covered in Chapter 15.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting

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