Unit Sizing; Electrical Service - Econar GeoSource Vara GV Series Installation And Operating Instructions Manual

c.
Miratic Acid
Cleaning
(Difficult
Scaling
and
Particle Buildup Problems)
l.
Consult installer due to dangerous nature
ofacids.
2.
Iron
out solutions
and
de-scaling products
are also
useful.
VI.
UNIT SIZING
Selecting the
unit
capacity
of
a
geothermal
heat
pump
requires
two
things:
A)
Earth Loop Configuration
and
Design Water
Temperatures.
B) Building Heat Loss/Heat Gain.
A.
Loop Configuration
and Design
Water Temperatures
Loop configurations include
the open and closed
loop
varieties. Heat pump capacity
and
flow
rate
requirements
vary depending on loop
configuration
(see Table 3).
1.
Closed Loop Systems
Closed loop
systems
use a
heat exchanger
of high density
polyethylene pipe buried underground to supply
a
tempered
water solution back to the heat
pump.
Closed
loops
operate at
higher
flow
rates than
open loops
since
the
entering water temperature
(EWT)
is
lower.
The loop
EWT
supplied to the heat
pump
has
a
great effect
on the
capacity of
the
unit in
the
heating
mode.
Earth loops in
cold climates are
normally
sized to supply a
wintertime
EWT
to the heat
pump from
32oF
down to 25oF,
which
minimizes the
installation
cost
of
the earth loop
and
still
maintains proper
system
operation. The unit GPM
requirements
and pressure drops
for loop pump sizing
is
available
in
Table 2.
When selecting
the heat
pump,
choose
a
unit that
will
supply the necessary heating or
cooling
capacity
at the
minimum
and
maximum
earth
loop temperature
conditions
respectively.
Example;
if
a
residential
system
requires 44,000 Btu/hr
to heat
a
house on an earth
loop
system
(designed
for
32oF
minimum wintertime EWT),
and 34,000 Btu/hr
to
cool
the house on an earth
loop
(designed for
77nF
summertime EWT),
a
Gx52x-x-Vxxx
GeoSource
Vara
heat
pump
is required.
2. Open Loop Systems
On
an
open loop
system the design water temperature
will
be the
well
water temperature in your geographic region.
Many cold climates
are
in
the
50oF range
for well
water
temperature. Flow
rate requirements
(in GPM)
and
unit
water-side
pressure
drops (in PSI)
at
50"F EWT
are
available in
Table
3. If
your well
water
temperatures
are
lower
than 50oF,
for
instance Canadian well water
can be
as
low
as
43T,
the
flow
rate must
be increased to avoid
leaving water
temperatures
below
the freezing
point.
If
well
water
temperatures are above 50"F,
as
in
some
southem
states
where well water
temperatures are above
70"F,
the
flow
rates may need to be increased to dump
heat more
efficiently in
the
cooling
mode.
Varying well water temperatures
will
have
little
effect on
unit
capacity
in
the
cooling
mode
(since the well
is
connected to the heat
pump
condenser), but can have
large effects on
the
capacity in
the
heating mode (since
the
well
is connected to the
evaporator).
If
well
water
temperatures are
to
exceed 70t'F,
special considerations,
such
as
closed loop
systems,
should
be addressed.
B.
Building Heat Loss/fleat Gain
The
space
load must be estimated accurately
for
any
successful
HVAC installation.
There are many guides
or
computer programs available
for
load estimation
including
the
ECONAR
GeoSource
Heat Pump
Handbook, Manual
J, and
others. After
the heat loss/heat
gain is completed
and
loop EWT
are established, the heat
pump
can
now be
selected
using
the
specifications
data.
Choose the
capacity of
the heat
pump
based on
both
heating
and
cooling load.
VII.
ELECTRICAL SERVICE
The main electrical service
must be
protected by
a
fuse
or
circuit
breaker,
and be capable
ofproviding
the amperes
required by
the
unit
at
nameplate voltage.
All
wiring
shall
comply with
the national electrical
code and,/or any
local
codes
that may
apply.
Access
to
the
line voltage
contactor is
gained through
the
knockouts provided
on
either
side
ofthe
heat
pump next to
the
front
corner.
Route
EMT or flexible
conduit with
appropriate 3-
conductor wire to
the
contactor.
9WARNING
- The
unit
must
be
properly erounded!9
VCAUUON:
Three-phase units
ruI
be
wired
properly
to insure proper compressor rotation. Improper
phasing may result
in compressor damage. An
electronic
phase sequence
indicator must
be used
to check supply-
wiring phase. Also,
the
"Wild"
leg of
the three-phase
power
must be connected to the middle leg
on the
contactor.
When supplying power to external water pumps
with
the
heat
pump's power supply,
use
only
impedance protected
motors. ECONAR
PumpPAKsrM
can be wired directly
to
the contactor in
the electrical
box.
The relay
will
energize
the
PumpPAKrM with
a
call for heating or cooling.
The
use
of
impedance
protected
pumps
eliminates
the need
for
additional fusing on
the PumpPAKrM.
8
)