Econar GeoSource DualTEK GV Series Installation And Operating Instructions Manual page 16

D. Temperature
Limitations
Be
aware
of
the operating range
of
the
geothermal
system
when sizing
the
particular
heat
pump.
An
operating range
of
15oF
(minimum for
heating) to
110oF
(maximum for
cooling)
is
required for
the earth loop side.
These
limits
have been established based on efficiency limitations
and
safety pressure switch
limits
(25-psi low-pressure cutout
and 400-psi high-pressure
cutout).
Hvdronic
side
limitations
have
a
minimum of
50"F
hydronic
entering
water temperature
and
a
maximum
of
130"F
hydronic
leaving water temperature range (entering water to
the
hydronic
side
below50oF gives low
head pressures
that
drives
the
suction pressure below
cutout conditions).
IX.
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
of
the 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
properlv erounded!9
VCAUTION:
Three-phase units
![sf
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 extemal water pumps
with
the
heat
pump's power supply,
use
only impedance protected
motors. An ECONAR
PumpPAKrM
can be wired
directly
to
the
contactor
and
grounded in
the
grounding
lug. A
relay (M6)
and terminal
block (BP) is supplied in
the
electrical box for
the
hydronic
side
pump.
The relay
will
start the
pump with
a
call from
the aquastat.
The
use
of
impedance
protected
pumps eliminates
the need
for
additional
fusing.
Do not connect more than
a
1/3
horsepower pump to
the
internal pump relay.
If
larger pumps
are required,
a
separate
power supply is
required to supply
the
pump. To
start
this pump
use
a24-
volt
relay
pulled in from
the
Y
and
X
terminals.
X.
24
VOLT
CONTROL
CIRCUIT
The wiring diagrams in Figures
8 and
9
shows the
low
voltage controls of
the heat
pump
and some
generic
extemal
control
schemes.
This
section
will
break down
the three basic components of
the
low
voltage circuit;
transformer, thermostat/aquastat,
and
conroller.
A. Transformer
Electrical
diagrams
are
provided in Figures
8 and 9, and
on
the
electrical box coverpanel ofthe heatpump. An
internal 24-volt,75 VA
ffansformer
is
provided
to
operate
all control features of
the heat
pump.
Even though
the 75
VA
transformer is larger than
the
industry
standrlrd
40
VA
transformer,
it
can
still
be overloaded
quickly
when
using
it
for control
equipment
like
zone valves or
zone
circulators.
Table 7
shows the transformer
usage
for
the
GeoSource
DualTEK
heat pumps.
Table
7
-
Transformer
If
the system's external controls require more than
the
VA
available for external
use
from
the
transformer,
an
extemal transformer
must be used. You
can
see
t}tat
in
Figure 2, the heat
pump's
internal transformer
can easily
power
the
extemal 24-Yolt system. In
contrast,
if
a
system contains components that
have their own power
supply, they must
be coupled to
the heat
pump.
This
can
be
accomplished using
an
isolation relay which
isolates
the
external
systems
power supply from
the heat
pump's
transformer (e.g. use the external
systems independent
power supply to
energize the
coil of
a
relay, passing a
signal
across the
Normally
Open
contacts from
the heat
pump's transformer).
The heat pumprs transformer
can
generally power simpler
control
systems consisting of
a
few relays or
zone
valves
(depending,
ofcourse,
on the
VA
draw
ofthe
components).
On more complicated control
systems the
transformers capacity is
used
up very quickly.
GNote:
For units operating
on
208V
electrical
service,
the
transformer
must be switched to
the correct lead (see
electrical
diagrams - Figures
8 and
9).
Units
are
factory
shipped with
the ffansformer
set
for 240V
service.
Operating
a
unit
on
208V with
the
transformer
set
to
240V
will
cause the
unit
to
operate
with
less than normal
control
voltage.
B. Thermostat/Aquastat
Consult
the
instructions ia
the thermostat box for proper
mounting
and
thermostat
operaLion.
7
.,
6
4
1
I
JJ
55
VA
20VA
14
I
Contactor
Pump Relav
BlowerRelay
Reversine
Valve
Controller
Thermostat
Solenoid
Valve
Total
Available