One other aspect we have to look over is the water temperature coming from the ground. As we mentioned previously, the efficiency depends on a group of several factors.

THE BORE HOLE:
We know it’s much better to not only to mention why this hole into the ground is so important, but to discuss how it works. There is a relative connection between what type of grout is used and how the ground heat exchanger is placed into the formation.

What is grout:

Grout is used to fill an empty space between the pipe loop and the wall of the bore hole.
The industry measures grout through conductivity. The higher the conductivity, the better for the heat transfer and performance of the equipment as well.
The most used material for the residential market is bentonite.
The conductivity number on the material is from 0.38 to0.45 Btu/hr.ft.F.( heat transfer rate, unit length of bore)
The  weight is from 8.9lb/gal to 9.8 lb/gal.
Another material which can be used is a thermal grout with conductivity from 0.85 to 0.95 Btu/hr.ft.F.
The only acceptable method to place a slurry into the bore hole is when the grout material is pumped from the bottom up. Treemy (?) pipe is sent into the bore hole at the same time when the earth loop is inserted. The conductivity number can also be easily increased without increasing the cost.