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SERVICING
1.4
The system operates at low stage cooling.
1.5
If the thermostat demand cannot be met on low stage
cooling, the CTK0* thermostat sends a request for high stage
cooling to the heat pump. The heat pump in turn sends a
request for high stage fan speed to the air handler/modular
blower. The AH control increases the blower speed to the
high stage cooling speed.
1.6
The heat pump’s unitary control energizes the high stage
compressor solenoid and switches the condenser fan motor
to high speed. The reversing valve remains energized.
1.7
The system operates at high stage cooling.
1.8
Once the thermostat demand is satisfied, the CTK0*
thermostat commands the UC control to end cooling
operation. The heat pump de-energizes the compressor,
condenser fan motor, and reversing valve. The UC control
continues providing a fan request until any cooling blower
OFF delays have expired.
2.0 Heating Operation
Outdoor Temperature Above the Heat Pump Balance Point
2.1
The CTK0* thermostat sends a request for the outdoor air
temperature to the heat pump. The heat pump returns an
outdoor air temperature that is above the balance point
temperature. Heat pump heating is enabled.
2.2
The CTK0* thermostat sends a request for low stage heat
pump heating to the unitary (UC) control in the heat pump.
The UC control receives the command and processes any
compressor and fan delays.
2.3
The UC control sends a request for low stage fan speed to
the air handler/modular blower. The blower energizes the
ECM blower motor at the appropriate speed.
2.4
The condenser energizes the compressor and condenser fan
motor at the appropriate low stage speeds.
2.5
The system operates at low stage heat pump heating.
2.6
If the thermostat demand cannot be met on low stage heat
pump heating, the CTK0* thermostat sends a request for
high stage heat pump heating to the heat pump. The heat
pump in turn sends a request for high stage fan speed to the
air handler/modular blower. The AH control increases the
blower speed to the high stage heat pump heating speed.
2.7
The heat pump’s unitary control energizes the high stage
compressor solenoid and switches the condenser fan motor
to high speed.
2.8
The system operates at high stage heat pump heating.
2.9
If the thermostat demand cannot be met on high stage heat
pump heating, the CTK0* thermostat sends a request for
auxiliary heat to the air handler/modular blower.
2.10
Upon receiving a demand for auxiliary heat, the air handler
control determines the appropriate airflow for high stage
heat pump + auxiliary heat operation and operates the
ECM blower motor at that airflow demand. The air handler
control determines which airflow demand is greatest and
applies that demand when operating the ECM blower motor.
2.11
The system operates at high stage heat pump heating plus
auxiliary heat.
2.12
Once the thermostat demand is satisfied, the CTK0*
thermostat commands the heat pump to end heat pump
heating operation. The compressor and outdoor fan motor
are de-energized.
The air handler/modular blower is commanded to end
auxiliary heat operation. The air handler control de-
energizes the electric heat sequencer outputs. The ECM
blower motor remains energized until any blower OFF delay
timing has expired.
Outdoor Temperature Below the Heat Pump Balance Point
2.1
The CTK0*** thermostat sends a request for the outdoor
air temperature to the heat pump. The heat pump returns
an outdoor air temperature that is below the balance point
temperature. Heat pump heating is disabled.
2.2
The CTK0*** thermostat sends a request for auxiliary heat
to the air handler/modular blower.
2.2
The air handler control energizes the ECM blower motor
at the auxiliary heat speed. The electric heat sequencer
outputs are also energized, thus energizing the electric
heaters.
2.3
The system operates at auxiliary heat.
2.4
Once the thermostat demand is satisfied, the CTK0*
thermostat commands the air handler/modular blower
to end auxiliary heat operation. The air handler control
de-energizes the electric heat sequencer outputs. The ECM
blower motor remains energized until any blower OFF delay
timing has expired.
3.0 Continuous Fan Operation
3.1
With a demand for continuous fan operation, the CTK0*
thermostat sends a fan request to the integrated air handler
control along with a fan demand. The control adjustable via
the CTK0* thermostat. The compressor delay is intended
to eliminate compressor noise during the reversing valve
shift. The compressor will energized (or re-energized) at high
stage.
3.2
If the thermostat demand for continuous fan is removed,
the CTK0* thermostat commands the integrated air handler
control to end continuous fan operation. The integrated AH
control immediately de-energizes the ECM blower motor.
4.0 Defrost Operation
4.1
While the system is operating in heat pump heating (see
2.0 Heating Operation
), the control in the outdoor unit may
determines that a defrost cycle is needed. Upon determining
that a defrost cycle is needed, the UC control de-energizes
the condensor fan motor and energizes the reversing valve.
4.2
The compressor may be de-energized for a short delay
during the reversing valve shift. (The delay period is
adjustable via the CTK0* thermostat. The compressor
delay is intended to eliminate compressor noise during the
reversing valve shift.) The compressor will energize (or re-
energize) at high stage.
4.3
The UC control sends a request for defrost operation to
the integrated air handler control. The air handler control
energizes the electric heat sequencer outputs and operates
the ECM blower model at the electric heat speed.
