Cooling Sequence Of Operation - Payne PY4G B Series Installation Instructions Manual

the temperature rise associated with each fan speed for a
given static pressure. Make sure that the speed chosen
delivers a temperature rise within the rise range listed on the
unit rating plate.
2. Remove the current speed tap wire from the "GAS HEAT"
terminal on the interface fan board (IFB) (Fig.18) and place
vinyl cap over the connector on the wire.
3. Connect the desired speed tap wire to the "GAS HEAT"
terminal on the interface fan board (IFB).
Cooling Fan Speed Set- - up (Dehumidification feature
not used) (Single Phase Models):
To change cooling speed:
1. Remove existing speed tap wire from the "COOL" terminal
on the IGC board. Add the wet coil pressure drop in Table
14 to the system static to determine the correct cooling
airflow speed in Table 8 that will deliver the nominal
cooling airflow listed in Table 1 for each size.
2. Connect the desired speed tap wire on the "COOL" terminal
on the IGC board.
Single Cooling Fan Speed Set-up (Dehumidification
feature not used) (3 Phase Models)
To change cooling speed:
1. Remove the vinyl cap off of the desired speed tap wire
(Refer to Table 8 for color coding). Add the wet coil
pressure drop in Table 14 to the system static to determine
the correct cooling airflow speed in Table 11 or 12 that will
deliver the nominal cooling airflow as listed in Table 1 for
each size.
2. Remove the current speed tap wire from the "LOW"
terminal on the interface fan board (IFB) (See Fig. 18) and
place vinyl cap over the connector on the wire.
3. Connect the desired speed tap wire to the "LOW" terminal
on the interface fan board (IFB).
Dehumidification Cooling Fan Speed Set- - up (Single
Phase Models):
IMPORTANT: Dehumidification control must open control
circuit on humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of
either a 24 VAC dehumidistat or a thermostat which includes
control of a 24 VAC dehumidistat connection. In either case, the
dehumidification control must open the control circuit on humidity
rise above the dehumidification set point.
1. Move shunt jumper on IGD board to "DH" (See Fig. 17).
2. Refer to airflow table (Table 10) to determine allowable
speeds for the dehumidification cooling fan speed. Speeds
that are not allowed are shaded in Table
3. Connect selected speed tap wire to "DHUM" terminal on
the IGC board. Verify that static pressure is in the acceptable
range for the speed tap to be used for dehumidification
cooling.
Two Cooling Fan Speeds Set-up (Dehumidification
feature used) (3 Phase Models)
IMPORTANT: Dehumidification control must open control
circuit on humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of
either a 24 VAC dehumidistat or a thermostat which includes
control of a 24 VAC dehumidistat connection. In either case, the
dehumidification control must open the control circuit on humidity
rise above the dehumidification set point.
1. Remove fan speed tap wire from the "LOW" terminal on
the interface fan board (IFB) (See Fig. 18).
2. Determine correct normal cooling fan speed for unit and
application. Add the wet coil pressure drop in Table 14 to
the system static to determine the correct cooling airflow
3. Remove the vinyl cap off of the desired speed tap wire
4. Refer to airflow tables (Table 11 or 12) to determine
5. Remove the vinyl cap off of the desired speed tap wire
6. Use any spare vinyl plugs to cap any unused speed tap
NOTE: For cooling operation, the recommended airflow is 350 to
450 CFM for each 12,000 Btuh of rated cooling capacity.
Continuous Fan Speed Set- - up (Single Phase Models):
To change continuous fan speed:
1. Remove existing speed tap wire from the "FAN" terminal
2. Connect the desired speed tap wire on the "FAN" terminal
Continuous Fan Operation (3 Phase Models)
When the DEHUM feature is not used, the continuous fan speed
will be the same as cooling fan speed. When the DEHUM feature
is used, the continuous fan will operate on IFB "LOW" speed
when the DH control lead is not energized, or IFB "HIGH" speed
when the DH lead is energized (see Fig. 18).

Cooling Sequence of Operation

With the room thermostat SYSTEM switch in the COOL position
and the FAN switch in the AUTO position, the cooling sequence
of operation is as follows:
1. When the room temperature rises to a point that is slightly
10.
2. The normally open contacts of energized contactor (C) close
3. The set of normally open contacts on the interface fan board
NOTE: Once the compressor has started and then stopped, it
should not be started again until 5 minutes have elapsed. The
cooling cycle remains on until the room temperature drops to a
point that is slightly below the cooling control setting of the room
thermostat. At this point, the thermostat breaks the circuit between
thermostat terminal R to terminals Y and G. These open circuits
deenergize contactor coil C. The condenser and compressor motors
stop. After a 60- -sec. delay, the blower motor stops. The unit is in a
standby condition, waiting for the next call for cooling from the
room thermostat.
25
speed in Table 11 or 12 that will deliver the nominal cooling
airflow as listed in Table 1 for each size.
(Refer to Table 8 for color coding) for the normal cooling
fan speed and place desired speed tap wire on "HIGH" on
the interface board.
allowable speeds for the dehumidification cooling fan
speed. In Table 11 or 12, speeds that are not allowed for
dehumidification cooling are shaded.
(Refer to Table 8 for color coding) for the dehumidification
cooling fan speed and place desired speed tap wire on the
"LOW" connection on the interface board (IFB). Verify
that static pressure is in the acceptable range for the speed
tap to be used for dehumidification cooling.
wires.
on the IGC.
on the IGC board.
Table 8 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange = Med --- High Speed
Red = Med Speed
Pink = Med --- Low Speed
Blue = Low Speed
above the cooling control setting of the thermostat, the
thermostat completes the circuit between thermostat
terminal R to terminals Y and G.
and complete the circuit through compressor motor
(COMP) to condenser (outdoor) fan motor (OFM). Both
motors start instantly.
(IFB) are closed which energizes a circuit to the indoor fan
motor (IFM).