Econar GeoSource Vara GV Series Installation And Operating Instructions Manual page 7

tContact
your local installer or ECONAR's Customer
Support
for loop
sizing requirements
in your
area.
Since
normal wintertime
operating entering water
temperatures
(EW-f)
b
the heat
pump
are
from
25oF
to
32T,
the solution
in
the earth
loop must include
antifreeze. GTF
and
propylene
glycol
are
conlmon
antifreeze
solutions. GTF
is
methanol-based antifreeze,
which
should
be
mixed
50Vo
with
water to achieve freeze
protection of
10oF. Propylene
glycol
antifreeze solution
should
be
mixed
25Va
with water to obtain a
15T
freeze
protection. DO
NOT
mix more that257o propylene
glycol with
water
in
an
attempt to achieve
a
lower
than
15oF
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
antifreeze.
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).
From
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.
Table
3
-
Side
Flow
Rates
Pressure/Temperalure
P/T)
ports should
be
installed
in
the
entering
and
leaving water lines of
the heat
pump on
a
closed
loop
system
(see Figure
2). A
thermometer
can be
inserted into
the
P/T ports to
check
entering
and
leaving
water temperatures.
A
pressure gauge can also be
inserted into
these
P/T ports to determine
the pressure
differential
between the entering
and
leaving water. This
pressure
differential
can then be
compared to the
specification
data on each
particular
heat
pump to
determine the
flow
rate
of
the system.
A
PumpPAKrM that is
individually
sized
for
each
application
can
supply pumping requirements
for
the
earth
loop fluid.
The PumpPAKrM
can also be used to
purge
the loop
system.
The
PumpPAKru
is
wired direcfly
to
the
contactor
and operates whenever the compressor
runs (see
Electrical
Diagram - Figure
4). If
a
PumpPAKru
is
not
used, a separate
pump
can be used
which is energized with
a
pump relay (note: electrical
code
will
require
a
fused discomect for pumps other than
PumpPAKsrM).
Filling
and
purging
a closed
loop
system are
very
important
steps to
assure
proper
heat
pump operation.
Each loop
must be
purged with
enough water
flow
to
assure
a
two feet per
second
flow
rate
in
each
circuit on
the
loop.
This
normally
requires a
lVz
to
3
HP high
head
pump to circulate fluid
through the loop to remove all
the
air out
of
the
loop
and
into
a
purging tank. Allow
the
pump to run
10
to
15
minutes after
the
last air bubbles
havebeenremoved.
Enough
attifreeze mustbe
added
to
give a 10T
to
151F freeze
protection to
the earth
loop
system.
This
amount should be calculated
and added
to
the
loop after purging is
complete. Aft.er antifreeze
has
been
installed
it
should
be measured
with
a
hydrometer,
refractometer or any other device to determine the actual
freeztng point of
the solution. Remember that
a
low
antifreeze
level will
lock
the heat
pump out on
low
pressure during wintertime
operation.
The purge pump
can be used
to pressurize
the system to
an
initial
static pressure
of
30-40
psi.
Make
sure the
system is at this pressure after the loop pipe
has had
enough
time to stretch. In order to
achieve the 30 to
40
psi
initial
pressure, the loop may need to
be
pressurized to
60 to
65
psi.
This static pressure
will
fluctuate
from
heating to cooling
season,
but the pressure should always
remain above zero
so
circulation pumps do not cavitate
and air cannot be
pulled into
the system.
SFor
information
regarding
earth
loop
installations contact
your
local
installer, distributor or factory representative.
B.
Open Loop Applications
An
open system gets its
name
from
the open discharge
of
water after
it
has
been used
by
the heat
pump. A
well
must be available that
can
supply all of
the
water
requirements
(see
Table
3)
of
the heat
pump along
with
any
other water requirements drawing off
that
same
well.
The well
must be capable
of
supplying the heat
pump's
required
flow
rate
for
up to
24 hours
per day on
the
coldest
winter
day.
Figure 3
shows the necessary components
for
water
piping of
an open
system. First,
a
bladder type pressure
tank with
a
"draw down" of
at
least
lYztines
the
well
pump capacity must
be
installed on
the supply side
of
the
heat
pump.
Shut
off
valves
and
boiler
drains
on the
entering
and
leaving water lines
are
necessary for future
maintenance issues.
A
screen strailer
is
placed
on the
supply
line with
a mesh size
of 40 or 60
and enough
surface area to allow for particle buildup
between
cleanings.
Pressure/Temperature (P/T) ports
are
placed in
the supply
and
discharge lines
so
that thermometers or
pressure
gauges can be inserted into
the water
stream.
5
Closed
Loop Opea.Loop
Flow
Model
SJlow
d**al)
dP
,(asi)
dP
{rs0
G(V,H)
36
8
5.5 4 1.3
G(Y,H)
52
11
5.2 6 1.6
G(V,H)
59 13
6.0
9
3.1
G(V,H)
67
t4
1.0
10 3.8