13SEQUENCE OF OPERATION
1.Incoming 120VAC
a.Full time power to the Main Control Switch
b.Full time power to the Variable Frequency Drive
2.Power On - When the main control switch is turned on:
a.120v is applied to the
b.120v is applied to the L.W.C.O. terminal L1 (if used)
c.120v is applied to the Fenwal Flame Safeguard Control
d.24v is applied to the TempTrac operating temperature control terminal L1
3.Call For Heat - If the TempTrac operating control senses a
a.The High Gas Pressure and Low Gas Pressure Switch (both optional) are energized and their safe condition is proved.
b.The thermostat contact on the Fenwal Flame Safeguard Control is energized.
c.The flame control will then verify the
d.Energizing the blower should close the airflow proving switch. If the
e.If the
4.Proof of Air Pressure Switch - The control will look for a signal from the
a.When the airflow generated by the blower is sufficient to cause the differential air switch to close, the 15 - second
b.During this period any flue products or combustible gases which may have settled in the water heater are evacuated.
5.
a.The flame control will monitor the current applied to the hot surface igniter.
b.If the flame control determines the proving current meets the threshold, a dwell time delay starts to assure the hot surface igniter has sufficient time to reach ignition temperature.
6.Ignition - When dwell time is completed a
a.The
b.During TFI the flame safeguard control will monitor the flame using flame rectification through the hot surface igniter.
c.If the flame control senses the presence of flame before the end of the TFI period, the igniter will be de- energized and the flame control will continue to monitor the flame, through the igniter, until the operating thermostat ends the call for heat condition.
7.Loss of Flame Signal
a.If the igniter fails to sense flame at any time, the igniter and gas valve will be
b.When the call for heat condition ends or flame failure occurs following the third TFI period (one time if CSD- 1), a
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