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50ZHK: Installation Instructions
Step 4 – Indoor Airflow and Airflow Adjustments
WARNING
!
UNIT OPERATION HAZARD
Failure to follow this caution may result in equipment damage or
improper operation.
For cooling operation, the recommended airflow is 350 to 450 cfm for
each 12,000 Btuh of rated cooling capacity.
Table 5
shows wet coil air delivery for horizontal discharge units.
NOTE: Be sure that all supply- and return-air grilles are open, free from
obstructions, and adjusted properly.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Disconnect electrical power to the unit and install lockout tag before
changing blower speed.
Blower speed tap can be changed by replacing the factory installed blue
low speed tap wire (cooling) with the unused black high speed wire in
unit control box. The red medium speed wire is factory installed to
operate with a call for supplemental electric heat. See unit wiring
diagram.
Be sure new airflow meets the range noted above and minimum electric
heat CFM, if equipped. Refer to
All model sizes are factory wired or rated airflow operation.
Step 5 – Sequence of Operation
Fan Operation
The FAN switch on the thermostat controls indoor fan operation. When
the FAN switch is placed in the ON position, the indoor (evaporator) fan
motor (IFM) is energized through the G terminal on the thermostat. The
motor's internal logic then provides power to the indoor (evaporator) fan
motor (IFM). The IFM will run continuously when the FAN switch is set
to ON.
When the FAN switch is set to AUTO, the thermostat deenergizes the
IFM (provided there is not a call for cooling). The contacts open and the
IFM is deenergized. The IFM will be energized only when there is a call
for cooling, in heat pump heating mode or if the unit is equipped with
accessory electric heat, the indoor-fan motor will also run while the
accessory electric heat is energized.
NOTE: Motors on this product are programmed for 60 second time
delay on tap 1 and 30 second time delay on tap 2. There is no time delay
on tap 3. The indoor fan will remain ON for the set time delay after G or
W2 is de-energized.
Cooling Operation
With a call for cooling (Y), the compressor, outdoor fan, and indoor fan
start immediately. When the cooling demand is met, Y de-energizes,
shutting the compressor, indoor fan and the outdoor fan.
Heating Operation
With a call for heating (Y), the compressor, outdoor fan, and indoor fan
start immediately. If Y cannot satisfy the heating demand, the auxiliary
or backup heat (W2) energizes. In case of staged heating, W3 is
energized if the demand is not met. When heating demand is met, W3,
W2 and Y sequentially de-energize shutting the compressor, indoor fan
and the outdoor fan.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 2
and
Table
5.
Continuous Fan
With the continuous indoor fan option selected on the thermostat, G is
continuously energized. The continuous fan speed will be the same as
the cooling fan speed.
Demand Defrost Mode
The defrost mode is factory set to an initial 60-minute time interval. It
may also be adjusted to an initial interval of 30, 90, or 120 minutes.
During operation, the control optimizes current defrost time based on the
previous defrost interval and previous defrost period. If the previous
defrost period is less than 2 minutes for two consecutive defrost cycles
the control will lengthen the defrost interval by 15 minutes, up to a
maximum of 120 minutes or 30 minutes greater than the original
setpoint, whichever comes first. If the previous defrost period is more
than 5 minutes for two consecutive defrost cycles the control will
shorten the defrost interval by 15 minutes, down to a minimum of 30
minutes or 30 minutes from the original setpoint, whichever is first.
After the defrost condition is satisfied, or after a maximum of 10 minutes
in defrost mode, the unit will resume normal heating operation.
ELECTRIC RESISTANCE HEATING
If accessory electric heaters are installed, on a call for "Emergency Heat"
the thermostat energizes W which energizes the heater relay and in turn
energizes the electric heaters. The IFM is energized which starts the
indoor-fan motor. If the heaters are staged, W2 is energized when the
second stage of heating is required. When the need for heating is
satisfied, the heater and IFM are de-energized.
12
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