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Discussion Starter · #1 ·
Which is more efficient, a single loop pipe, or circuits?

Is higher or lower soil resistance better?

Using LoopLink.

If I start at my foundation and just dig one continuous trench and lay a single 3/4" HDPE pipe in it; I get soil resistance of 3.92 hr ft F/Btu.

If I lay out circuits, I get 4.93.

Which is better?

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Discussion Starter · #2 ·
I should clarify. As I understand it, the LoopLink app shows the least amount necessary so the difference in soil resistance is more than likely due to one having hundreds more feet of pipe in the ground.

This is LoopLinks definition of Soil Resistance:

Soil Resistance: The heat transfer resistance (hr-ft-F/Btu) in the horizontally-trenched GHEX. Soil resistance is a function of loop pipe diameter, spacing and configuration of the pipes in the trench, the center-center spacing between trenches, the number of trenches to be installed, and soil thermal conductivity.

For more information on soil resistance, refer to Tables 5.17-5.29 (Chapter 5, pages 64-69) in IGSHPA's Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide.
"Resistance" = bad in my mind, does that mean I want a LOWER value?
 

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Yes you want a lower number.

This is highly influenced by distance between pipes. Your diagram of the circuits will be highly effected by this. You want to try to space them out.

You use circuits when the resistance to the flow of water is too great for a reasonable sized pump. ¾" pipe is going to be very restrictive to 17 gpm even before talking about the +3300 ft.

FYI:
 

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Just some thoughts of my own, I have no knowlege or facts of such systems.

I would think the further the spacing of the individual lines the better.
The system that uses the most of the land area the better.

As this type of geo loading will be mostly cooling of the earth, there will be over years a reduction in temp of the earth in the area of the loop field.

Just another thought...
I was just pondering the possibility of a reversing valve at the house to change the direction of the flow through the field,
As the beginning end of the field will be subject to the most cooling of the earth compared to the other end.

If the field could be reversed in flow direction it could balance the eventual cooling of the entire field.
If not even during mid winter.

Just some thoughts for the experts to shoot down. :)
 

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Just some thoughts of my own, I have no knowlege or facts of such systems.

I would think the further the spacing of the individual lines the better.
The system that uses the most of the land area the better.

As this type of geo loading will be mostly cooling of the earth, there will be over years a reduction in temp of the earth in the area of the loop field.

Just another thought...
I was just pondering the possibility of a reversing valve at the house to change the direction of the flow through the field,
As the beginning end of the field will be subject to the most cooling of the earth compared to the other end.

If the field could be reversed in flow direction it could balance the eventual cooling of the entire field.
If not even during mid winter.

Just some thoughts for the experts to shoot down. :)
All that would do is recool water that's already gathered heat. Essentially equalizing the temperature of the field, without benefit.
 
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