5188235-YIM-B-1016
54
Johnson Controls Unitary Products
Flash Codes or Error Messages
The UCB will initiate a flash code associated with errors within
the system. Refer to flash code on the Simplicity Lite Control
(See Table 31) or sent error message to the LCD Smart
Equipment Control.
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 22 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
time after the call for heat is satisfied.
Figure 25: Gas Valve Piping
Two Stage Furnace Only
If a W1 only call for heat from a two stage thermostat is present,
then a two stage furnace will start on high fire for 1 minute and
then reduce to low fire until the call for heat is satisfied or a W2
call for heat is received. If a W2 call for heat is received while in
low fire operation, then the ICB will immediately move to high
fire operation. If a W1 and W2 call for heat is present, then the
furnace will remain on high fire operation until the W2 call for
heat is satisfied.
Automatic staging of a two stage furnace using a single stage
thermostat is possible. To achieve automatic staging of a two
stage furnace using a single stage thermostat, cut the 440/GY
wire that runs from pin 2 of the S3 connector on the (UCB) unit
control board to P2-4 on the ignition control board. Cut the wire
1/2" from the S3 mate-n-lock connector. Wire nut or tape off the
1/2" wire. Attach the other end of the 440/GY wire to the R
terminal on the UCB, or to the TB1 power strip.
The unit will operate the same as a W1 only call for heat for 10
minutes. If the call for heat is not satisfied in the 10 minutes,
then the ICB will move to high fire operation until the W1 call for
heat has been satisfied.
Gas Heat Operation Errors
During furnace operation, the ICB monitors the flame sense
circuit, the centrifugal switch, the primary limit switch and the
roll out switch. If a signal from any of the inputs moves to a fault
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 22: 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
Table 21: Electric Heat Limit Setting
Voltage
kW
Temperature Limit
Switch
Open Temperature
°F
Gas Valve
Gas main
Main valve
To main burner
Redundant valve
To pilot burner
