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Mezzo Hanging Patio Heater
29/10/10
Wiring Diagram
Fig 5
Flame Sensor Current Check
Flame current is the current which passes through the flame from the sensor to ground.
The minimum flame current necessary to keep the system from lockout is 0.7 microamps.
To measure flame current, connect an analog DC microampmeter to the FC- and FC+
terminals. Meter should read 0.7
µ
A or Higher. If the meter reads “0” on scale meter leads
are reversed. Disconnect power and reconnect meter leads for proper polarity.
CONTROLLER OPERATION
Heat Mode
When a call for heat is received from the Switch or Thermostat supplying 24 volts to TH/W,
the control will reset, perform a self check routine, flash the diagnostic LED for up to four
seconds, and a pre-purge delay begins. Following the pre-purge period the gas valve is
energised and sparks commence for the trial for ignition period.
When flame is detected during the trial for ignition, sparks are shutoff immediately and the
gas valve remains energised. The thermostat and main burner flame are constantly
monitored to assure the system continues to operate properly. When the thermostat is
satisfied and the demand for heat ends, the main valve de-energised immediately.
Failure to light - Lockout
Should the main burner fail to light, or flame is not detected during the trial for ignition
period, the control will go into lockout and the valve will be turned off immediately.
Recovery from lockout
requires a manual reset by either resetting the thermostat or
removing 24 volts for a period of 5 seconds.
If the thermostat is still is still calling for heat after one hour the control will automatically
reset the attempt to ignite the burner again.
