Burnham 8H manual

4.Honeywell EI Sequence of Operation

a.Normal Operation

i.Thermostat or operating control calls for heat. Vent Damper (if used) opens.

ii.Ignition Module Terminals PV, MV/PV and the Ignition Terminal are energized. Terminals PV and MV/PV power the Pilot Valve in the Gas Valve supplying gas to the Pilot. The Ignition Terminal supplies voltage to the Ignition Electrode creating an electric spark to ignite the Pilot.

iii.The sensing Circuit between the Q348 Pilot Burner and the IGNITION MODULE proves the presence of the Pilot Flame Electronically and the Ignition Terminal is de-energized.

iv.Terminals MV and MV/PV of the IGNITION MODULE are energized and supply power to the Main Gas Valve. The Gas Valve is energized allowing main gas flow, and ignition of Main Burners.

v.Call for heat ends. Ignition module is de- energized, de-energizing gas valve, and extinguishing pilot and main flame. Vent

Damper (if used) closes.

b.Safety Shutdown

i.Limit: Automatically interrupts power to the Ignition Module and Gas Valve(s), extinguishing pilot and main flame, when water temperature exceeds set point. Maximum allowable temperature is 250°F. Circulator continues to operate with call for heat, Vent Damper (if used) closes. Normal operation resumes when water temperature falls below set point.

ii.Blocked Vent Switch: Automatically interrupts main burner operation when excessive flue gas spillage occurs.

Circulator continues to operate and Vent Damper (if used) remains open with call for heat. If blocked vent switch is activated do not attempt to place boiler in operation. Correct cause of spillage and reset blocked vent switch.

iii.Flame Roll-out switch: Automatically interrupts main burner operation when flames or excessive heat are present in vestibule. Circulator continues to operate, Vent Damper (if used) remains open with call for heat. Control is single use device.

If flame roll-out switch is activated, do not attempt to place boiler in operation. Correct cause of spillage and replace flame roll-out switch.

iv.Pilot

–Pilot failure can occur during the start-up or the operating cycle of the boiler. Any pilot failure of the Q348 Electronic Pilot, after ignition of pilot flame will close the main gas valve in 0.8 seconds.

–For approximately 90 seconds after failure of the Q348 pilot, the module through the ignition terminal will try to reestablish pilot flame. If no pilot flame can be sensed by the flame rod circuit, terminals PV and

MV/PV are de-energized and the module will lock out on safety. Five to six minutes after shutdown, the IGNITION MODULE restarts the ignition sequence. The ignition trial, shutdown, and wait sequence continues until either the pilot lights or the Thermostat is set below room temperature (to end the call for heat). The ignition sequence can be reset by setting down the Thermostat for one minute.

c.Trouble Shooting Guide. See Page 66.

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