Service Reference Manual | SEQUENCE OF OPERATIONS |
Simplified Sequence - HWC122, 182, 242, 302 (w/Fenwal
Refer to Figure 2-5
CALL FOR HEAT
1.The thermostat energizes the
2.The
3.The
4.As the combustion blower reaches full speed, it closes the pressure switch.
5.A
6.The gas valve solenoid energizes at the same time as the spark terminal, causing the gas valve to open and the burners to light.
7.The spark ignitor continues to spark for approxi- mately six seconds or until flame is sensed by the flame sensor electrode.
8.The unit will operate normally until the
9.When the signal is interrupted, the gas valve de- energizes and closes immediately.
10.The combustion blower relay
11.The blower control board starts a
12.Following the
FLAME SENSE
1.After the spark electrode has lit the main burners, the ignition control waits approximately six seconds for a flame sense signal.
2.If a flame sense signal is not received after approxi- mately six seconds, the ignition control
3.The thermostat
4.The unit initiates three trials for ignition (flame sense) before system lockout.
CALL FOR COOLING
1.A call for cooling closes the circuit from R to Y and G.
2.A
3.With a
4.When the cooling call is completed, G and Y de- energize. The contactor opens immediately, stop- ping the compressor and the outdoor cooling fan. When G
FAN ON
1.When the thermostat switch is moved to the “FAN ON” position, the circuit between R and G closes.
2.The
3.Fifteen seconds after terminal G on the blower control board energizes (or immediately after - see note below), the circulating air blower starts.
4.When terminal G on the blower control board de- energizes, the timer to turn off the circulating air blower starts. The blower turns off after 90 seconds (see note below).
Note: Heatcraft blower control boards have a G “on” delay of 15 seconds and an “off” delay of 90 seconds. Tridelta blower control boards have no “on” time delay and a 60
