GSZH5 Service Manual
62
SYSTEM OPERATION
If more than two heater elements are on
the heater assembly, it will contain a second heat
the temperature indoors will continue to drop. The
open between 30 to 70 seconds and heater elements
thermostat will remove the 24Vac from HR1. Both set of
contacts on the relay opens within 30 to 70 seconds and
3.0 Cooling Operation
On heat pump units, when the room thermostat set to the
cooling mode, 24Vac is supplied to “O” which energizes the
reversing valve. As long as the thermostat is set for cooling,
the reversing valve will be in the energized position for
cooling.
3.1 On a demand for cooling, the room thermostat
energizes “G” and “Y” and 24Vac is supplied to “Y” at the
heat pump and the “G” terminal on the EBTDR board.
The heat pump turned on in the cooling mode and after
a 7 second on delay, the relay on the EBTDR board is
energized and the blower motor starts.
3.3
thermostat removes the 24Vac from “G” and “Y”.
3.4
4.0 Heating Operation
On heat pump units, when the room thermostat set to the
heating mode, the reversing valve is not energized. As long
as the thermostat is set for heating, the reversing valve will
be in the de-energized position for heating except during
a defrost cycle. Some installations may use one or more
outdoor thermostats to restrict the amount of electric heat
that is available above a preset ambient temperature. Use
of optional controls such as these can change the operation
of the electric heaters during the heating mode. This
sequence of operation does not cover those applications.
4.1
the room thermostat energizes “G” and “Y” and 24Vac is
supplied to “Y” at the heat pump unit and the “G” terminal
on the EBTDR board. The heat pump is turned on in the
heating mode and the blower motor starts after a 7 second
on delay.
the heat pump, the temperature indoors will continue to
drop. The room thermostat will then energize terminal “W2”
for second stage heat and 24Vac will be supplied to heat
sequencer HR1 on the heater assembly.
4.3 HR1 contacts M1 and M2 will close will close within 10
to 20 seconds and turn on heater element #1. At the same
time, if the heater assembly contains a second heater
element, HR1 will contain a second set of contacts, M3 and
M4, which will close and turn on heater element #2. The
blower motor is already on as a result of terminal “G” on
demand.
If more than two heater elements are on
the heater assembly, it will contain a second heat
heater elements if available. If the second stage heat
the temperature indoors will continue to drop. The
open between 30 to 70 seconds and heater elements
4.4 As the temperature indoors increase, it will reach
a point where the second stage heat demand, “W2”, is
remove the 24Vac from the coil of HR1. The contacts on
heater element(s). The heat pump remains on along with
heat will still be present.
4.5
room thermostat will remove the 24Vac from “G” and “Y”.
5.0 Defrost Operation
On heat pump units, when the room thermostat is set to
the heating mode, the reversing valve is not energized.