Hybrid
Horizontal
Spacekeeper
–
Installation
Operation
Maintenance
Manual
OPERATION
R090303
Installation
Operation
Maintenance
Manual
is
subject
to
change
without
notice
Page
10
The
unit
circuit
board
incorporates
six
relay
outputs
with
the
following
functions:
•
K1
–
Auxiliary
relay
for
cooling
valve
on
a
two
‐
valve
unit
or
heat
valve
on
a
dehumidification
unit.
•
K2
–
Heating
Relay
•
K3
–
Alarm
Relay
•
K4
–
Compressor
Relay
•
K5
–
Low
Fan
or
Fan
Relay
for
belt
drive
units
•
K6
–
High
Fan
or
Compressor
#2
on
belt
drive
units
Each
of
these
relays
have,
in
parallel,
a
green
LED
indicator
that
lights
up
when
the
relay
is
energized.
The
circuit
board
incorporates
digital
inputs
that
are
opto
‐
coupled
to
a
24V
AC
source.
These
have
amber
LED
indicators
located
near
the
input
locations
which
are
lit
when
the
input
is
closed.
The
inputs
include:
•
High
Pressure
Switch
•
Low
Pressure
Switch
•
Heat
Call
(W
on
thermostat
terminal)
•
Cool
Call
(Y
on
thermostat
terminal)
•
Fan
Call
(G
on
thermostat
terminal)
•
Auxiliary
(A
on
thermostat
terminal)
•
Compressor
shutdown
(24V
AC
signal
thru
O/O).
Providing
a
continuous
24V
potential
to
O/O
will
terminate
and
prevent
compressor
operation.
This
can
be
used
for
duty
‐
cycling,
minimizing
power
consumption
during
an
emergency
power
period
or
during
sufficiently
low
outdoor
air
temperatures
which
allow
for
free
cooling
–
all
while
maintaining
the
heating
function.
•
Unit
shutdown
(24V
AC
signal
thru
A/O).
Providing
a
continuous
24V
AC
potential
to
A/O
will
terminate
and
prevent
unit
operation.
This
can
be
used
for
a
night
shutdown.
On
both
arrangements
a
single
24V
AC
signal
can
shutdown
many
units.
¼
VA
is
required
per
unit.
Finally,
the
board
has
four
analog
inputs
provided
via
thermistors.
These
inputs
are
as
follows:
•
Ta
–
Discharge
Air
Temperature
•
Tr
–
Refrigerant
Temperature
•
Tw
–
Outgoing
Water
Temperature
•
Co
–
Condensate
Level
Ta,
Tr,
And
Tw
are
10k
Ohm
NTP
thermistors,
while
Co
is
a
100
Ohm
NPT
thermistor.
These
Inputs
do
not
have
LED
indicators.
