NATE accreditation as
three passed and the
other two are eligible to
take the test again. One
student is working with
an economic development group to start
his own geothermal business.
For the lab portion of the class, Persons
arranged for the students to visit an actual
jobsite and install a geothermal system.
“I met the homeowner, Marishka Wile,
at a Columbus Green Building Forum con-
ference,” Persons explains. “It was quite
a coincidence that she is a professor at the
Hocking College main campus. She was very
interested in sustainable technologies, and the longer we
talked, the more excited she became about the prospect of
installing a geothermal system in her new home.”
The two-story log home consists of a main floor with a
master suite, spacious living and kitchen area, and a second
;oor bedroom, bath and sleeping lo;. It has high-e;ciency
windows and a solar orientation to provide for roof or ground-
mounted solar collectors in the future. Many of the materials
in the home are made from recycled material. Wood from an
old ;re-damaged homestead tree was used to cra; support
beams, decorative stair railings, stair treads, furniture and a
rustic breakfast bar.
For the mechanical system, Persons specified a 3-ton
WaterFurnace Envision unit that uses a two-stage Copeland Ultra Tech scroll compressor; a 50-gal Rheem Marathon
hot water tank is connected to allow the geothermal to provide more than 60% of the domestic hot water. An AprilAire
Model 400 humidifier helps maintain relative humidity,
which is crucial for maintaining the dimension of the logs.
;e geothermal loop is a horizontal two-pipe trench. ;ere
are three trenches; each is 5-;. deep (18-in. to 24-in. wide)
and each contains 600-;. of 3/4-in. polyethylene pipe set in
the bottom corners of each trench. For safety reasons related
to cave-in hazards and the narrow width of the trenches,
students were not permitted to enter the trenches and used
notched 2x2s to position the geothermal loop lines in the
bottom of the trenches. Once the lines were in place, clean
back;ll was added to protect the loop lines prior to blading-in
the remaining back;ll.
All connections are fusion welded with heat fusion and
socket tools. Students practiced fusion welding and constructed the 1-1/4-in. polyethylene supply and return
manifolds in lab class prior to their installation at the project site. The geothermal loops are filled with a solution of
80% deionized water and 20% inhibited, nontoxic propylene
glycol. Loop design was based on a minimum operating tem-
Students helped install a 3-ton geothermal
system for this newly built log home.
perature of 30°F and a maximum of 90°F.
To prepare for design of the closed loop,
students took soil samples to determine
the composition and moisture content as
they relate to thermal conductivity and
design of the closed-loop installation.
“We had a high moisture content and excellent thermal
conductivity, so we were very fortunate in that regard,” Persons says. “We thought we would have to contend with ledge
rock or shale layers, but we found nice, moist, clay-like, sandy
silt soil with water seepage ;lling the trenches in the lower
;e system was put into operation in December 2009 and
made it successfully through an unusually cold winter. Wile
moved in a few months later.
“I was very impressed with the professionalism of the
installation and the e;ciency of the system. I hadn’t realized
geothermal heat would be so warm,” Wile says.
st s t
eo - s o
e dh n h
A new Regenerative Sustainable Agricultural program is
currently under development at HECI; it will focus on
biotechnologies and agricultural energy. Eventually, this program will be housed in another new building on the campus,
currently in the design phase and expected to open in about
three years. A third building will follow to house an envisioned Transportation Technology program.
“Changes aren’t going to happen overnight,” Hutton says.
“I tell our students to be patient and that school is where they
need to be right now. We have 40 to 50 years of a problem
we’re trying to fix here — there has to be a change. Many
Americans are very uneducated about where energy comes
from and what goes into producing it. Right now we have to
focus on educating, educating, educating.”
To learn more…
Lisa Murton Beets is a Cleveland-based freelance writer and
frequent contributor to Green Mechanical Contractor and
Radiant Living magazines.