Geoexchange systems utilize the Earth for heating and cooling.
Photo courtesy MOTHER EARTH NEWS editors
Installation of a geoexchange system is not so much
difficult as it is time-consuming. The installer needs to
have an excellent background in ducting, high-voltage
(240-volt) and low-voltage (24-volt) controls wiring,
plumbing, loop purge and fill procedures, and a working
knowledge of refrigeration systems. The majority of heating
and air conditioning contractors do not have technicians
with the background necessary to handle a geoexchange in
stallation like an experienced and certified GSC.
Conventional heating contractors tend to focus on
relatively simple, one-day furnace and air-conditioning
installations. By contrast, a closed-loop geoexchange
installation can take a crew of three workers up to five
working days to complete a project, with roughly 60% of the
time dedicated to installing piping and filling the loop.
If you decide to move ahead on your own, you should still
use a local GSC as a source of information and possibly as
a service partner to look after the system while you're
installing it. The services Geo-Source One provides for
those who wish to take a direct role in a system
installation include establishing a contract as a
consultant in the project, performing an energy analysis
for the home, sizing equipment, designing ductwork and
closed loop, and providing for delivery of equipment
materials and any specialty tools needed for installation.
As construction progresses I arrange for site inspections
and assistance where the tasks may exceed the time or
ability of the owner. I find this method of managing a DIY
project adds con s istency to the installation and helps to
avoid many of the potential pitfalls that can beset a
In addition to the trenching and pipe laying work outlined
in the main article , you'll need to adapt your ductwork to
fit a geoexchange system.
On main floors, the supply air registers are located six
inches from outside walls and positioned beneath windows or
adjacent to outside doors. The return air intakes for the
first- and any upper-level floors are all situated "high
side wall" (HSW). The return air in a finished basement is
located "low side wall" (LSW). I've found this means of
collecting return air produces the most uniform temperature
within the structure, with little more than a few degrees
difference between basement- and upper-level temperature.
By comparison, older duct designs that use low side wall or
floor level returns have inherently warm ceilings, cold
drafty floors and a basement area that is cold and
uncomfortable year round. Constantly operating a fan in
these situations helps a little, but serves more to create
cold drafts since the bulk of the circulation is from the
Every contractor has a preference for ducting material, and
for trunk lines the favorite is usually sheet metal. My
preference, however, is a ridged, foil-faced fiberglass
product called duct board. Available from a number of
sources, duct board is shipped in cartons of 4x10 sheets.
The sections can be shipped flat and assembled on-site.
When properly installed, the high-density duct board
maintains a system with no air leakage. Also, the people in
whose homes we run duct board trunk lines do not notice the
"white noise," or random popping and booming caused by the
expansion and contraction of metal trunk lines. The use of
flexible canvas collars at connections to the system will
also help reduce any harmonics between motors and sheet
metal. However, air turbulence within the sheet metal will
still produce some noise at the registers.
With the proper advice and guidelines, laying your home's
geothermal piping can be challenging (but money saving)
work. Here are a few pointers to help you dig safely:
Before you dig, contact the local utility location
service. Allow plenty of time for their agents to mark out
the site and locate any underground utilities.
Mark utility easements, septic tanks, tile fields, water
well casings and underground piping that needs to be
Figure out where excavated soil will be stored as an area
is cleared and keep it away from the edges of any trench to
prevent cave-ins. Trench spoils should sit at least three
feet back from any five-foot trench wide enough to hold a
person. In a trench that big, even a small cave-in can
involve more than 1,500 pounds-a weight you do not want
plummeting in on top of you. Complete all work in a trench
as quickly as possible and get out. Also, it's a good idea
to work out an alternative means of escape from any
excavation. A ladder works well, but I often carry a shovel
and place it across the top sides of the trench. This way,
a quick jump and pull-up can make for a quick escape.