403134-YIM-E-0311
44
Johnson Controls Unitary Products
Flash Codes
The UCB will initiate a flash code associated with errors within
the system. Refer to UNIT CONTROL BOARD FLASH CODES
Table 25.
Reset
Remove the call for heating by lowering the thermostat setting
lower than the conditioned space temperature.This resets any
flash codes.
Electric Heat Anticipator Setpoints
It is important that the anticipator setpoint be correct. Too high
of a setting will result in longer heat cycles and a greater
temperature swing in the conditioned space. Reducing the
value below the correct setpoint will give shorter “ON” cycles
and may result in the lowering of the temperature within the
conditioned space. Refer to Table 20 for the required electric
heat anticipator setting.
Gas Heating Sequence Of Operations
When there is a W1 call for heat, the heat relay (RW1) is
energized by the unit control board (UCB). The RW1-1 contacts
immediately close energizing the ignition control board (ICB).
The ICB checks the state of the flame sense circuit, the roll out
switch, the centrifugal switch and the primary / auxiliary
temperature limit switch circuit. If they are in the expected state,
then the ICB energizes the draft motor and verifies that the
centrifugal switch located on the end of the draft motor closes.
After the centrifugal switch closes, a 15 second heat exchanger
purging period is completed. After this purging period, the ICB
will simultaneously energize the pilot gas valve and the ignition
coil. Once the flame sensor senses a pilot flame is present, the
ignition coil is de-energized. The ICB checks for pilot flame
stability and once the ICB is satisfied that the pilot flame is
stable, the main gas valve is energized by the ICB. The UCB
will energize the indoor blower after a 45 second delay from the
call for heat. The ICB and UCB both monitor the furnace safety
devices during the furnace operation. When the call for heat is
satisfied, the ICB closes the pilot and main gas valves and
performs a 30 second purging of the heat exchanger by
continuing the operation of the draft motor. The UCB continues
the operation of the indoor blower for a configurable amount of
Table 19: Electric Heat Limit Setting
Voltage
kW
Temperature Limit
Switch
Open Temperature
°F
208-1-60
5
1
140
7
1,3
140
10
1,2,3
140
15
2,4,6
140
20
1,2,3,4,5
140
6
150
30
1,2,3,4,5,6
150
230-3-60
5
1,2,3
140
7
1,2,3
140
10
1,2,3
150
15
2,4,6
140
20
1,2,3,4,5,6
150
30
1,3,5
160
2,4,6
150
460-3-60
7
2,4,6
140
10
2,4,6
140
15
2,4,6
140
20
3
160
30
3
150
575-3-60
10
2,4,6
140
15
2,4,6
140
20
5
160
30
5
150
Table 20: Electric Heat Anticipator Setpoints
Heater
Kw
Voltage
Setting, Amps
TH1
TH2
5
230-3-60
0.35
-
7
0.35
-
10
0.35
-
15
0.35
0.19
20
0.35
0.38
30
0.35
0.38
7
460-3-60
0.35
-
10
0.35
-
15
0.35
-
20
0.37
0.29
30
0.37
0.29
10
575-3-60
0.35
-
15
0.35
-
20
0.37
0.29
30
0.37
0.29
