S & J Heating and Cooling

Quality GeoExchange/GeoThermal Installations
for
Mid-Michigan

  Loop Design ...

Loop piping is made of a dense, flexible material called polyethylene and is warranted against defects for 50 years.
In residential installations, 3/4 in. pipe is generally used and is joined with thermal-fusion fittings.

          When it comes to ground loops, there are two principal types : open-loop and closed-loop. 
Closed-loop systems are more common and can be trenched or bored underground horizontally or installed 
vertically like water wells. If you have a pond nearby, piping can even be laid on the pond bottom.
The pond size required for the system to operate correctly depends on the heating and cooling requirements
of the structure, but 1/4 acre averaging 8 ft. deep is considered a minimum size. Pond loops can be less expensive 
than other types of closed loops if the pond is close enough to the structure to be heated.
If a pond is over 150 feet from the building, the savings can be negligible or even non-existent.

     The most common type of installation utilizes a horizontal loop.
In this situation, pipes are laid in trenches that extend from the building to an appropriate distance determined
by the heating and cooling load. The greater the load (required heating and cooling), the longer the trenches.
Up to 6 pipes can be laid in a 3 foot wide trench. This involves 3 pipes taking the water out into the yard
at a depth of 6 feet and 3 pipes bringing the water back at a depth of 4 feet.
Generally, 2 trenches are dug, side by side, each containing 6 pipes.
This is by far the most popular method for installing a closed loop in our area and the method we
generally recommend if there is enough unencumbered space available.

When a property won't accomodate this much trenching, a vertical, closed-loop system is the next best option.
In this case, a well driller typically drills several holes without casings 150 to 200 feet deep.
The contractor then drops two pipes joined with a U fitting at the bottom into each hole and joins all pipes 
from all holes in a common pit 5 to 6 feet deep. Before filling the pit, each bore hole is grouted to meet state and 
local codes. While vertical, closed-loop systems are more expensive to install than the horizontal variety due to
the added drilling costs, they work as well or better than horizontal loops at transferring heat and are an ideal
option when available space is limited.

Open-loop installations involve fresh ground water being pumped directly from a well and through a 
geothermal system. The water is then delivered back into the aquifer through a second well or into a nearby 
ditch, stream or lake. These systems are quite efficient, however, the costs of an additional well, the added cost 
of operating the pump, the need for a water filtration system and the resulting discharge of several thousand
gallons of water daily have all led to a decline in the popularity of this method.