Daikin ComfortNet DX7TC Service Instructions Manual page 88

SERVICING
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: 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 condenser. 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 condenser energizes the compressor and condenser fan
motor at the appropriate low stage speeds.
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 condenser. The condenser in turn sends a
request for high stage fan speed to the air handler/modular
blower. The blower increases the blower speed to the high
stage cooling speed.
1.6 The condenser's unitary control energizes the high stage
compressor solenoid and switches the condenser fan motor
to high speed.
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 condenser de-energizes the compressor and
condenser fan motor. The UC control continues providing
a fan request until any cooling blower OFF delays have
expired.
2.0 Heating Operation - Auxiliary/Emergency Heat
2.1 The CTK0* thermostat sends a request for emergency heat
to the air handler/modular blower.
2.2 The air handler control energizes the ECM blower motor
at the emergency heat speed. The electric heat sequencer
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
variable speed ECM motor at fan demand provided by the
88
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*
Communicating Thermostat
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 components. 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* thermostat 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 acquired 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 condenser fan
motor at the appropriate low stage speeds. The reversing
valve is also energized.