Econar GeoSurce Vara 2 Plus GV Series Lnstallation And Operating Lnstructions page 8

viscous
at
low
temperatures and cannot be pumped
through
the earth
loop.
Insufficient
amounts of antifreeze
may result
in
afreeze 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 temperatues 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
*Cupro-Nickel Well
Water
Coil
Pressure/Temperature
(P/T) ports (ECONAR
part number
70-0450)
must 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 wator temperafures.
A
pressure gauge can also be
insefied
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 PumpPAKrM is wired
directly
to
the contactor
and operates whenever
the
compressor
runs (see Electrical
Diagram - Figure
4). If
a
PumpPAKrM
is
not
used, a separate
pump
can be used
which
is energized with
a
pump relay (note: electrical
code
will
require
a
fused disconnect
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
1/z
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
have been removed.
Enough antifreeze
must be added
to
givefreeze protection
to
15T
betow the minimum loop
design temperature.
This
amount should
be
calculated
and added to
the
loop
after purging is
complete.
After
antifreeze
has been
installed,
a solution
sample should
be measured with
a
hydrometer, refractometer or any other device to
determine
the actual freezing point. Remember that
an
inadequate 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 sfretch. 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
static pressure
should
always remain
above 20
psi
so
circulation
pumps
do
not
cavitate and air
cannot be
pulled into
the
system.
EFor
information
regarding
earth
loop
installations contact your
local
loop installer, ECONAR distributor
or
GeoRep.
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
lYz times
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
strainer
is
placed
on the
supply line with
a
mesh size of 40 or 60
and enough
surface
area
lo allow for
particle buildup
between
cleanings.
Pressure/Temperature
@iT)
ports
are
placed
in
the supply
and discharge lines
so
that thermometers or
pressure
gauges can be
inserted
into
the water
stream.
On the
well
water discharge
side
of
the heat
pump,
a
flow
control
valve must
be
mounted next to
the heat
pump to
regulate
the
maximum
water flow
through
the
unit. A
solenoid valve is then installed
and
wired
to the accessory
plug (PA)
on the controller of
the heat
pump.
This
valve
will
open when
the
unit
is
running
and
close when
the
unit stops. A
visual
flow
meter is
then installed to allow
visual inspection
of
the
flow
requirements.
The
flow
meter
can also be
useful in
determining when
maintenance
is required
(if
you can't
read the
flow,
cleaning is required,
see
Water Coil
Maintenance).
6
GV/GH
38
|
S
2.8
5
2.6*
GV/GH
48
I
tr
5.2
6
3.0*
GV/GH
s8
|
r:
7.5
8
6.0*