Gas Heating Sequence Of Operations; Gas Heat Operation Errors; Electric Heat Anticipator Setpoints; Gas Valve Piping - Johnson Controls ZE Series Installation Manual

Table 21: Electric Heat Limit Setting
Temperature Limit
Voltage kW
5
7
10
230-3-60 15
20
30
7
10
460-3-60 15
20
30
10
15
575-3-60
20
30
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.
Table 22: Electric Heat Anticipator Setpoints
Heater
Voltage
Kw
5
7
10
230-3-60
15
20
30
7
10
15 460-3-60
20
30
10
15
575-3-60
20
30
Johnson Controls Ducted Systems
Open Temperature
Switch °F
1,2,3 140
1,2,3 140
1,2,3 150
2,4,6 140
1,2,3,4,5,6 150
1,3,5 160
2,4,6 150
2,4,6 140
2,4,6 140
2,4,6 140
3 160
3 150
2,4,6 140
2,4,6 140
5 160
5 150
Setting, Amps
TH1
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.37
0.37
0.35
0.35
0.37
0.37

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.
Redundant valve
Gas main
Gas Valve
Figure 23: Gas Valve Piping

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
state, then the ICB immediately closes the pilot and main gas
valves. The ICB will determine the device that is signaling a
fault and flash a code for that device. A primary limit trip,
centrifugal switch trip or flame sense fault triggers a temporary
TH2
lock out. An auxiliary limit or a roll out switch trip requires
-
intervention to reset the ICB. The UCB also monitors the
-
primary limit and gas valve.
-
0.19
Temperature Limits
0.38
0.38
The primary limit is located such that the temperature
-
sensitive switch can sense the temperature of the heat
-
exchanger tubes. On single or two stage models the limit is
-
mounted just above the inlet of the heat exchanger tubes on
0.29
the right side. If a primary limit (LS) fault occurs (the primary
0.29
limit opens due to excessive heat exchanger temperature),
-
then the ICB will flash the appropriate code (Table 32) and
-
monitor the primary limit. The UCB will energize the indoor
0.29
blower and the ICB will energize the draft motor while the
0.29
primary limit is open. When the primary limit closes and the
call for heat still exists, the ICB will start the ignition sequence
6021974-UIM-A-1120
Main valve
To main burner
To pilot burner
53