Discussion in 'Vertical and Horizontal Loops' started by waterpirate, May 25, 2010.

  1. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I just got a set of prints in with all the usual "as typical " stamped all over them. One thing caught my attention though. The mechanical plan calls for a chemical shot feeder to be included in the loop piping, for a closed loop vertical system. Anyone have a point of refferance on this? I am assuming that it is to address water quality in the loop? Why not spec a given water quality to be used and tested for the system? Do you think that the engineer thinks so poorly of the pe pipe and joints that he is anticipating a large demand on the native water from the auto fill? Ant comments?
  2. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Most of the plans we see on commercial buildings have a glycol feeder.
    I have never understood why.
    Don't want to ask and give the engineers another reason to spout engineering double speak in a condescending manner. ( sorry Curt :eek: )
  3. Looby

    Looby Member Forum Leader

    Not for geo. It's very misleading to describe the HDPE geo ground loops
    as having "a certain amount of flexure." The pipe's thermal expansion
    coeffiicient is greater than that of water; so, when the loop's temperature
    rises, its pressure actually falls (for pressurized, closed loop systems).
    Overall, pressure vs. temperature effects are largely self-compensating,
    and the pipe is elastic enough to handle the remaining pressure swings.

    I don't know about the materials used in solar water systems (or the
    temperature swings they must endure), but pressurized, closed loop
    domestic geo systems don't need expansion tanks or glycol feeders.

    BTW, I believe methanol is more common than glycol in geo -- due to
    its lower viscosity. Volatility isn't much of an issue in closed loop geo
    systems, which have much lower maximum temperatures than solar.


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