SERVICING
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2.2 The air handler control energizes the ECM blower motor
at the emergency heat speed. The electric heat se-
quencer outputs are also energized, thus energizing the
electric heaters.
2.3 The system operates at emergency heat.
2.4 Once the thermostat demand is satisfied, the CTK0*
thermostat commands the air handler/modular blower to
end emergency 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
energizes the variavble speed ECM motor at fan demand
provided by the thermostat. The fan demand provided by
the thermostat will be 30%, 50%,or 70% of the air
handler's maximum airflow capability. The continuous
fan demand is set from the thermostat as low, medium,
or high.
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.
DVPTC/MBVC with DZ**TC Heat Pump and CTK0* Com-
municating Themostat
The DVPTC or MBVC air handle/modular blower matched
with a DZ**TC condensing unit and CTK0* communicating
thermostat constitute a network. The three components, or
subsystems, making up the system communicate with one
another with information passed between all three compo-
nents. This leads to a somewhat non-traditional manner in
which the system components receive commands for system
operation. All system commands are routed from the
component through the network to the appropriate destination
component.
NOTE:
Communicating heat pump systems are designed to
utilize a balance point temperature. The balance point
temperature in part controls heat pump operation. If the
outdoor temperature is below the balance point, the heat
pump is disable and only electric heat is available for heating.
The balance point temperature is set via the CTK0* thermo-
stat in the advanced installer's configuration menu.
The CTK0* thermostat also allows the user to disable the
electric heaters in the air handler/modular blower depending
on the outdoor temperature. The electric heaters are disabled
If the outdoor temperature is above the set point. All heating
is supplied by the heat pump.
The outdoor air temperature is aquired from the outdoor air
temperature (OAT) sensor included with the ASZC/DSZC
heat pump models. Faults with the sensor will affect heating
operation.
NOTE:
The individual subsystems will cease operation if the
request for operation is NOT refreshed after 5 minutes. This
is a built-in safe guard to prevent the possibility of runaway
operation.
1.0 Cooling Operation - Low and High Stage Cool
1.1 The CTK0* thermostat sends a request for low stage
cooling through the network to the unitary (UC) control in
the heat pump. The UC control receives the command
and processes any compressor and fan delays.
1.2 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.
1.3 The heat pump energizes the compressor and con-
denser fan motor at the appropriate low stage speeds.
The reversing valve is also energized.
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 con-
denser fan motor at the appropriate low stage speeds.
2.5 The system operates at low stage heat pump heating.
