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most efficient piping of HW rads: "TIBO"

ECW Member Posts: 14
Manufacturer of my newly acquired Stelrad panel radiators recommends TIBO (top-in, bottom-out) supply-return piping config for each radiator. Says its 4% more efficient. My HVAC contractor says logic is that BITO or BIBO (bottom-in, top-out, or bottom-in, bottom-out) make more sense to him. Manufacturer says is a matter of the design of the rads and the pressure drop, that a unit extracts heat more efficiently; whereas contractor says that since heat rises, supply the bottom and the top takes care of itself. Average temp will be 135F.


  • CMadatMe
    CMadatMe Member Posts: 3,086
    Let's See

    A manufacture makes the product, tests the product and recommends the install of the product but the contractor who installs the product doesn't use their recommendations. Easy anwser what I would do. Find another contractor or have him install it per the manufacturers recommendations.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • TonyS
    TonyS Member Posts: 849
    The same manufacturers

    mounted the pumps on the return of their boilers for many years. Following anyone blindly is never a smart move. Most times they are correct but they are far from perfect. How many times has Triangle tube changed the inlet and outlet position on the phase three? Question everything!
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,250
    I think there are photos of rads

    on the wall in infrared that show bottom in and bottom out is most even distribution of heat in a radiator. The hot water will displace the cold water best in this piping.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • jp_2
    jp_2 Member Posts: 1,935
    interesting question

    I wonder if they are looking at a constant circ application of tradition on/off situation?

    i could see thermal  siphoning helping out in an on/off control system.

  • ECW
    ECW Member Posts: 14
    They didn't say ...

    Manufacturer supplies several generic piping diagrams (2 pipe; reverse return; series) and rad attachment option illustrations. They recommend 2 pipe and the illustration with TIBO configuration says: 4% more efficient. I assume that refers to the transfer of the heat from water to its emittance from the rads. They do suggest outdoor reset and room thermostates along with TRV's/panel.
  • jp_2
    jp_2 Member Posts: 1,935
    flat panel rads act like

    some panel rads have vents like baseboards, so I could see where you would get a little more heat out if the top is hotter than the bottom.  this would help the convection currents up through the panel.
This discussion has been closed.