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Primary/secondary piping

PaulPaul Member Posts: 31
On a primary loop how close can there be 90 degree fittings from spirovent and pumps.


  • hot rodhot rod Member Posts: 7,094
    2-4 pipe diameters

    is one rule of thumb, try not to close couple the ells downstream of the pump.

    However many of the "boxed" and pre-built panel piping systems have components close coupled on the inlet and discharge side of the circs to save space.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • PaulPaul Member Posts: 31

    I can do 10"-15" from elbows to pumps and spirovent. Do you recommend piping into secondary circuit vertical from hoz. primary loop tees.
  • hot rodhot rod Member Posts: 7,094
    piping off P/S

    I would suggest every connection to a P/S have check protection. Ghost flow is always a potential, and it depends on many factors as to how much un-wanted flow you could see.

    Most circs have checks installed so one side is covered. A spring check or zone valve would assure the other side is protected.

    Consider a hydraulic separator also. These multi purpose devices provide excellent air, dirt, magnetic separation, in addition to eliminating the primary loop piping. A true 4 in 1 device.

    It also eliminates the temperature drop you see as you take off the primary loop. Every branch teed into the separator will see the same temperature.

    It cleans up the piping, saves time and money on the installation, and assures that all the circs behave with one another regardless of their size and brand :)

    Several brands to chose from, here is one that I am familiar with.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • PaulPaul Member Posts: 31

    On a single zone on the secondary loop would you install check valve and flow check valve. Have anybody used the flange flow checks from webstone.
  • NRT_RobNRT_Rob Member Posts: 1,009

    IF the primary loop will run for anything other than this zone.

    if this zone is the only thing running, I would be looking hard at why I was doing primary/secondary in the first place.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
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