Geothermal Efficiency

Discussion in 'Open Loop' started by adccon, Sep 5, 2010.

  1. adccon

    adccon New Member

    Hello all,

    I am trying to search for answers or at least how to find some answers here.

    I have a new home and have 4 geothermal (open loop) units installed. All are FHP units and ES series (I believe). I have 3, three ton and one 2 ton, for a total of 11 tons. These are paired with a goulds pump (33GS20) and franklin motor and controls.

    The problem is that i am not sure if these are working at the appropriate efficiency or not. I believe they are not, but honestly I don't have a good frame of reference since this is a new home. Currently I have no way to monitor flow, pressure or temperature across each unit.

    This is an open loop where I use the same well for domestic water. What is the starting point for determining if these are working correctly or not. I have read several posts which seem to indicate that too much flow cant be a bad thing.

    What controls do I need and where would I obtain them and at what relative cost?

    As a side note i have de-superheaters on 2 of the units but only one that is hooked up, but it doesn't seem to work as well as other posters indicate. I suspect this could be harmed by too much flow, but again, i need some direction on where and how to start.

    Thanks for your help.
  2. Water flow on new system

    As a baseline, figure 1.5 gpm per ton per unit. If you watch it, you can tweak the flow to get best efficiency vs. water pumping power. Too much water can erode the coils, and too little can create overheating or freezing problems at extreme weather limits. Your installer should have already set this up, and reported the start up figures to you.
  3. Flow adjustments part 2

    After re-reading your post..It seems you do not have the necessary controls to monitor pressure, temperature and flow. The unit should have a PT plug or Pete's plug entering and leaving the unit. This allows service tech instruments to record temp and pressure. the water flow is calculated by the pressure drop across the inside coil, which is provied on a chart from the manufacturer. Lacking all this, you can simply throttle the water flow until reasonable temperature drops or rises are recorded across the indoor coil. You can get a thermometer that surface records pipe temperature and be close enough.That is in heating, the water leaving will be colder than water entering, and in cooling the leaving water is warmer. A safe rule of thumb is 10-12 degree temp change in an open loop, but watch cold temp in colder climates. I have set units for 20 degree temp diff for customers who are water usage sensitive with success. If the machine exceeds its own limit, it will shut down. May require tweaking over a season or two.

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