20
SYSTEM OPERATION
GPC/GPH13[24-60]M24*
GPH13**M24* Heat Pump Units
On a call for first stage heat, the contacts of the room
thermostat close. This energizes terminals R to Y and R to
G, the low voltage circuit to the contactor is completed
starting the compressor and outdoor fan motor. This also
energizes the indoor blower through the normally open
contacts of the EMR and EBTDR after a 7 second on delay
on the PSC equipped units, and instantly on units with the
GE X13™ motor.
When the thermostat is satisfied, breaking the circuit be-
tween R to Y and R to G, the compressor and outdoor fan
motor will stop. The indoor blower will stop after the EBTDR
65 second off delay on PSC equipped units, and after the
programmed 60 second off delay on units with the GE X13™
motor. When auxiliary electric heaters are used, a two stage
heating single stage cooling thermostat would be installed.
Should the second stage heating contacts in the room
thermostat close, which would be wired to W1 at the unit low
voltage connections, this would energize the coil(s) of the
electric heat relay(s). Contacts within the relay(s) will close,
bringing on the electric resistance heaters. If auxiliary
electric heaters should be used, they may be controlled
by outdoor thermostats (OT18-60A or OT/EHR18-60A).
Emergency Heat Mode (Heat Pumps)
NOTE: The following only applies if the unit has an approved
electric heat kit installed for auxiliary heating.
GPC/GPH PSC Equipped Models Only:
With the thermostat set to the emergency heat position and
a call for 2nd stage heat, R to W1 will be energized. This will
energize the electric heat sequencer. When the normally
open contacts of the heat sequencer close, this will energize
the PSC blower motor through the normally closed contacts
of the EMR and also energize the electric heat contactor
which will energize the electric resistance heat.
GPC/GPH X13 Equipped Models Only:
With the thermostat set to the emergency heat position and
a call for 2nd stage heat, R to W1 will be energized. This will
energize the electric heat sequencer and the GE X13TM motor.
The electric heat contactor will be energized through the
normally open contacts of the electric heat sequencer. The
indoor blower will be energized through W from the thermo-
stat.
DEFROST CYCLE
Package Heat Pumps
The defrosting of the outdoor coil is jointly controlled by the
defrost control board and the defrost thermostat.
Solid State Defrost Control
During operation the power to the circuit board is controlled
by a temperature sensor, which is clamped to a feeder tube
entering the outdoor coil. Defrost timing periods of 30, 60, or
90 minutes may be selected by connecting the circuit board
jumper to 30, 60, or 90 respectively. Accumulation of time for
the timing period selected starts when the sensor closes
(approximately 34° F), and when the room thermostat calls
for heat. At the end of the timing period, the unit’s defrost
cycle will be initiated provided the sensor remains closed.
When the sensor opens (approximately 60° F), the defrost
cycle is terminated and the timing period is reset. If the de-
frost cycle is not terminated due to the sensor temperature,
a ten minute override interrupts the unit’s defrost period.
CY W2 R R DFT
TEST
DF1
DF2
JUMPER WIRE
90
60
30
A
FAN OPERATION
Continuous Fan Mode
GPC/GPH PSC Equipped Models Only:
If the thermostat calls for continuous fan, the indoor blower
will be energized from the normally open contacts of the EMR
which is energized through the normally open contacts of the
EBTDR after a 7 second delay.
Anytime there is a call for continuous fan, the indoor blower
will be energized through the normally open contacts of the
EMR which is energized through the normally open contacts
of the EBTDR, regardless of a call for heat or cool.
If the thermostat is not calling for heat or cool, and the fan
switch on the thermostat is returned to the automatic
position, the fan will stop after a 65 second delay.
GPC/GPH X13 Equipped Models Only:
If the thermostat calls for continuous fan, the indoor blower
will be energized from the G terminal of the thermostat to the
X13 blower motor.
If a call for heat or cool occurs during a continuous fan call,
the GE X13
TM
motor will always recognize the call for the
highest speed and ignore the lower speed call
If the thermostat is not calling for heat or cool, and the fan
switch on the thermostat is returned to the automatic
position, the fan will stop after the programmed 60 second off
delay on units with the GE X13
TM
motor.
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