Earth Loop Water Piping; Closed - Econar GeoSource 2000 GV Series Installation And Operating Instructions Manual

IV.
EARTH LOOP WATER
PIPING
Since
water is the
source
of
energy
in
the
wintertime
and
the energy sink
in
the
summertime, good water supply is
possibly
the
most important requirement of
a
geothermal
heat
pump
system
installation.
There
are
two
common
types
of
water supplies, closed
loop
systems and open
loop
systems.
A.
Closed
Loop Applications
A
closed
loop
system
recirculates
the same
water/antifreeze solution through
a
closed
system
of
underground high-density polyethylene
pipe.
As
the
solution passes through the
pipe, it
collects heat
(in
the
heathg mode) that
is being transferred
from
the
relatively
warm surrounding soil through
the
pipe
and
into
the
relatively
cold
solution.
The solution is circulated to the
heat
pump, which pulls
heat
out of the solution,
and
then
back through
the
ground to extract more
heat
from
the
earth.
The GeoSource 2000 is
designed
to
operate on
either
vertical
or horizontal closed loop
applications. Vertical
loops
are
typically
installed
with
a
well drilling rig up to
200 feet
deep or
more. Horizontal
systems are
typically
installed with excavating or trenching equipment
approximately six to eight feet deep, depending on
geographic location
and
length
ofpipe
used. Earth loops
must be
sized
properly for
each
particular geographic
TO/FROM
CLOSED LOOP
area,
soil type,
and
individual
capacity requirements.
Contact your local
installer or
ECONAR's
Customer
Support
for loop
sizing requirements
in your
area.
Since
normal
whtertime
operating entering water
temperatures
@Ury)
to the heat
pump
are
from
25oF
to
32oF,
the solution
in
the
earth loop must
include
antifreeze. GTF
and
propylene glycol
are common
antifreeze
solutions. GTF
is
methanol-based
antTfreeze,
which
should be mixed
50Vo
with
water to achieve freeze
protection of
10oF. Propylene
glycol
antifreeze solution
should be
mrxed25Vo with water to obtain a
15oF
freeze
protection. DO
NOT mix
more than25%o
propylene
glycol with
water
in
an
attempt to achieve
a
lower
than
15T
freeze
protection,
since more concentrated mixtures
ofpropylene glycol
become too viscous at
low
temperatures and cannot be
pumped through
the earth
loop.
Insufficient amounts of antifreeze may result
in
a
freeze
rupture
of
the
unit,
and can cause
unit
shutdown
problems during cold weather operation (when
the heat
pump
experiences the
longest run
time)
due to
loop
temperatures
falling below
the freeze
protection of
the
loop solution.
Flow rate requirements
for
closed loops are higher than
open
loop
systems because
water temperatures supplied to
the heat
pump
are
generally
lower (see Table
3).
Between
2.5 to
3.0
gallons per minute
(GPM)
per ton
are
required
for proper operation of
the heat
pump
and the
earth
coupled heat exchanger.
\
f
\
Figure
1-
Closed Loop
Water Plumbing
4
.Jl
IN
OUT
PmPPAK
Presre'/
Tmposhre
(P/T) Pofis
J
il
il
il