Closed Pond Loop

Discussion in 'Geothermal Loops' started by gmartin, Mar 11, 2015.

  1. gmartin

    gmartin New Member

    I am new to this but hope I can get some info from here.

    I oversee the building and grounds of a large church in Northern Indiana. We are presently getting to replace our air to water chiller with a new unit. The contractor we are working with mentioned going to a new chiller for the high demand cooling load in the summer 120 tons, but in the winter I still need around 28 tons of cooling for our 4 pipe system.

    We have a 4 acre lake onsite and I am wondering if it would be possible to do a closed pond loop system tied to our outdoor chiller loop (usingt the same pump and gycol) to pull the 28 tons or more needed inthe wintertime for cooling?

    Any ideas on how to size the loops, or a calculator for this?

    It would save us a bunch of electricity and demand costs to go this way for the wintertime. Once outside air temp hits a preset, we woould take the pond loop out of the circuit via control valves.
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    What is the design temperature of the fluid in your existing 4-pipe system?
  3. gmartin

    gmartin New Member

    Up to 60 degree outdoor air temp, I can get by with existing chiller providing 42-58 degree water. It cycles on for a 20 minute cycle then off for a 30 minute cycle for the entire 18 hr scheduled day. The water temp changes during the day with scheduled changes in the setpoints (42-58 degrees). The chilled water is needed to provide cool offices that pick up heat from people load or west exposure heat gain.
  4. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    In the winter, with some number crunching, you can very likely get your 28 tons. I would just use a heat exchanger between the exterior pond piping and the building loop. The exterior pond loop could be open or closed depending on your maintenance preferences.

    So, yes, it is likely a very good energy savings option.

    But then again, so would opening windows in the winter:)
  5. gmartin

    gmartin New Member

    We plan on using a heat exchanger for the air/water chiller gycol loop and figured on using the same heat exchanger for the pond loop.
    It there any info online or calculators online to compute the loop lengths needed and gpm flow?
  6. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    You are going to want someone to sign off on this - may actually be a requirement in some areas.

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