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energize
the
2od
compressor
contactor.
eNote
-
Ensure
there
is
always
a
delay
time
between the operation
of
the
two
compressors
to
avoid
nuisance
low-pressure lockouts.
5.
Hydronic Circulator Pump Control
The hydronic circulator pump is
energized either
directly
with
the
compressor contactor through the 3-pole
terminal
block (BP) or
through
an
isolation relay having its
24yac
coil
wired to
the
Y
and
X
terminals.
6.
4-Way Valve Control
When 24Vac
is
applied
to
the
O
terminal on the
wiring
block,
the controller
energizes
its O
output
to
provide
24Vac power
to
the reversing valve
(VR),
to
switch
the
refrigerant
circuit
to
the
cooling
mode.
7.
Compressor Lockouts
The
controller
will
lock
out the compressor
if
either
of
the
following
switches
open: 1)
high-pressure
(600 psig),
2)
Iow-pressure
switch
(50 psig
on
ground
loop
or
65
psig on
ground water),
or 3)
discharge refrigeraat
temperature
(275"F).
A
lockout condition
means
that the
unit
has shut
itself
down
to
protect
itself,
and
will
not
come
back
on
until
power has been
disconnected
(via the
circuit
breaker)
to
the heat
pump
for
one
minute.
Problems that
could
cause a
lockout
situation include:
l.
Low
water
flow
or extreme water
temperatures
2. Internal
heat
pump operation problems
3.
Cold
ambient air temperature conditions
8If
a
lockout condition
exists, the heat
pump
should
not
be reset
more fhan
once;
anfl
a
service
technician should
be
called immediately.
VCAUTION
-
Repeated reset
may
cause severe damage
to
the system and
may
void
warranty.
The
cause
of
t}re
lockout
must
be
determined
and
corrected.
8.
System
Diagnostics
The
controller
is equipped
with
diagnostic
LED lights
that
indicate
the
system status
at
any particular
time.
The
lights
indicate
the
following
conditions:
1"24Yolt
systempower
GREEN
2.
Fault or
Lockout
YELLOW
3.
Anti-short-cycle
mode
RED
If
a
room
thermostat
is
installed
with the
heat
pump
system and has
a
lockout indicator, the controller
will
send a
signal
from
L
on
the
terminal
strip
to
a
LED
on
the
thermostat to indicate
a
lockout
condition.
9.
24 Vac Fuse
The conffoller
has
a
glass-cartridge
fuse located
on
the
circuit
board adjacent
to
the
24Yac power connector. The
green system
power
LED
will
be
off
if
this
fuse
is
open.
A
spare fuse
is located
in
the saddle attached
to
the side
of
the 24Yac power
connector,
and the GW240 also
has
a
miniature rocker-type
circuit
breaker located
on
the
divider-wall
in
the
electrical
box. eNote
-
Ensure
the
new
fuse
fits
tightly
in
the
fuse clips after replacement.
12
10. Plug Accessory
(PA)
The Plug
Accessory
output
is
internally
connected
to
the
Ml
output and
is
energized whenever
Ml
turns
on
the
compressor contactor. The
maximum rating of this output
is
l0VA
sealed and
20VA
inrush
and
is
typically
intended
to
power
a24Yac
ground water solenoid valve.
11.
Alarm Output
This
output
is a
2-position screw terminal
connector
identified
as
"Fault
Test" on the controller board and
as
DO
on the
wiring
diagram.
It
is
an
isolated
dry
contract
ouQut
(0.1 ohm resistance)
that
closes
during
a
controller
lockout
and
is
intended
for
use as an
input to
a dial-out
type
of monitoring
system.
The
maximum
electrical
rating
is
2mA
up
to
30Vac or
50mA
up
ro
40Vdc.
IX.
STARTUP
/ CHECKOUT
Before applying
power
to
the
heat pump, check
the
following
items:
-
Water
supply
plumbing to
rhe heat
pump
is
completed
and operating.
Manually
open the water
valve on well
systems
to
check
flow.
Make
sure
all
valves are
open
and
air
has been
purged
from a
loop
system. Never
operate
the
system
without
correct water supply
flow
on either the ground
side
or
the
hvdronic
side.
-
All
high
voltage
and
all low
voltage
wiring is
correct
and
checked
out, including wire
sizes,
fuses
and
breakers,
Set system
to the
"OFF'position.
-
The
heat
pump is located
in
a
warm
area (above 45oF).
(Starting
the
system
with low
ambient
temperature
conditions
is
more
difficult.) Do not
leave
the
area
until
the space is
brought up to operating
temperatures.
-
Hydronic
side water
temperatures
are warrn
enough
(50S
or above) to
start
in
the
heating
mode.
Apply
power to
the
unit.
A
4
minute 35
second
delay on
power
up is
programmed
into
the
controller
before
the
compressor
will
operate.
During this time,
the
pump relay
will
energize
the hydronic side-circulating pump.
Verify
the
flow
rate
and
temperature
of
the
hydronic
side
flow.
The
following
steps
will
ensure
the
system
is
heating
and
cooling properly.
After
the
initial
time-out period,
the
red
indicator
light on
the
conffoller
will
shut
off.
The
heat
pump is now ready
for
operation.
-
Turn
the
heating setpoint
to its
highest
temperature
setting, and place the
system
to
run
in
heating.
The
compressor should
start
I
to 2
seconds
later.
If
an
electronic thermostat
is
used,
it *ay
cause
its
own
compressor delay
at
this time, but
the compressor
will
come
on after
the
time-out period.
-
After
5
minutes
of
heating operation, check
hydronic-
side
return and
supply
water
temperatures.
A
water
temperature rise
of
10oF
to
15oF
is normal
(variation
in
water temperature and water
flow
rate
can cause
slight
variations). Use a single
pressure gauge
to
check
the
fluid
pressure
drop through
the
heat
exchangers to
I
I
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