Georgia Think OUTSIDE the box - closed loop in aqueous well

Discussion in 'Maintenance and Troubleshooting' started by redneck_savant, May 1, 2016.

  1. redneck_savant

    redneck_savant New Member

    You are correct, even though doing it in this manner does save me up to $200 a month over conventional HVAC.
    That's precisely the reason I am looking to use a closed loop system and a recirculating pump that doesn't have to overcome the huge amount of head that a traditional well pump does.
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    However, the fact that this was piped all in one continuous pipe and is only 1" pipe, creates a huge pressure drop. While an open system supplies probably around 63F in your neck of the woods, a closed system swings more, requiring more flow. Doubling the flow increases the pressure drop 4 folds. Like I said, if you are unwilling to change the pipe diameter you might want to stick with what you have.
  3. redneck_savant

    redneck_savant New Member

    I am sure you are correct, but it still saves me up to $200 a month. That's why I was hoping to set up a more efficient closed loop system - even with 1" line it's going to have a lot less head than a traditional well pump. I know it's not optimal, but it would sure create a hell of a lot less load on my wells.
  4. redneck_savant

    redneck_savant New Member

    I understand the difference between the amount of heat exchanged in open vs closed loop systems - I've monitored the temp of water and it turns out the heat exchanges pretty well in a smaller diameter PE pipe. When the system was closed the incoming temp remained constant at that of the well water. I also could not physically fit a closed 2" loop in the 6" well with the existing plumbing and wiring for the current well (the diameter of my current well pump is 4", and dropping a 1" pipe 80' below the pump gave me another 160' of line immersed in flowing water.)

    The only part I could feasibly switch to 2" pipe is the horizontal pipe to the wells, and I don't know if that would be worth the effort or expense. I'd much rather simply install a pump topside and cut the well pump out of the loop. What I need help with (and my initial question) is as follows:

    2) What kind of flow center can handle pumping water thru 3500 feet of 1" pipe (two 500 ft wells and the horizontal runs) with a flow rate sufficient to allow this unit to function properly?

    By properly, I mean at least as good as it does now. Because now, right now, it works very well.
  5. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Tell us what the flowrate through the equipment is right now.
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Even if you have 7 gpm flow, kind of borderline for a 5 ton, you have over 150 ft/hd of pressure drop. About 80ft/hd at 5 gpm. At the end you might get by 3-4 gpm out of it. You get by with it because your water temp is around 65F in Georgia. But given that flow you get about 20F of delta T out of it. Going down to maybe 40F for heating and up to 95F in cooling mode. That is still within the operating parameters of the heat pump. So with a single 26-99 flow center you get about 4 gpm, with 2 pumps you get 5 gpm.
    Good luck.
  7. mrrxtech

    mrrxtech Member

    Your location must be Northern GA since you have granite under you property, not the water aquafer that Southern GA has. I lived in Waynesboro GA below Augusta for a "Spell" which is how I know the geology.

    Since you're up North, the winters may be colder than Southern GA. Heating season causes a closed loop to cool down which affects the efficiency of your Unit.
    Having a closed loop and an Open loop Geothermal in the North, I can see how an Open loop allows greater efficiency when heating due to the roughly 55 degree water coming from the well in the winter rather than having a 30 degree or less closed loop temperature.

    For the Open Loop Geothermal Unit I purchased an 86 gallon well tank isolated from the house water by installing a check valve in the water supply to the tank, so it serves the Geothermal Unit only. This helped reduce the well pump cycle time greatly on a 3 Ton Unit. Using the well water as the heat sink in the winter will allow more efficient Geothermal Unit operation, but the well pump will use more power than a closed loop flow center.

    You can try both types of water loops then pick the one that heats best (open loop) but costs more to operate. Saving power use with a closed loop could require a backup heat in the winter when the closed loop goes below 30 degrees.

    If you can switch easily from closed loop to open loop, you could use the closed loop without antifreeze in the cooling season only, then open the loop for the heating season. If someone forgets to change the loop to open in the winter, your Unit will shut down at 30 degrees in the water loop assuming you haven't clipped the jumper that changes the Freeze protection to 20 degrees assuming you have a closed loop with antifreeze.

Share This Page