Rheem P-M406 Operating Instructions - Page 45

ELECTRICAL - ELECTRONIC IGNITION IID WARNING HIGH VOLTAGE For qualified technicians ONLY NOTE: Some heaters may be equipped with an ignition module that shuts off pilot gas if pilot fails to light. To reset, interrupt power to heater. START TURN GAS SUPPLY OFF. TURN THERMOSTAT (CONTROLLER) TO CALL FOR HEAT POWER TO PC BOARD? NO (24 V NOMINAL) YES SPARK ACROSS IGNITER/SENSOR GAP? NO YES TURN GAS SUPPLY ON PILOT BURNER LIGHTS? NO YES NOTE: Before troubleshooting, familiarize yourself with the start-up and check-out procedure. Check line voltage power, low voltage transformer, limit controller, thermostat (controller) and wiring. Make sure that the line voltage is NOT 208 VAC. Pull ignition lead and check spark at PC board. Spark Okay? YES NO Replace the PC board. • Check ignition cable, ground wiring, ceramic insulator and gap, and correct. • Check boot of the ignition cable for signs of melting or buckling. Take protective action to shield cable and boot from excessive temperatures. • Check that all manual gas valves are open, supply tubing and pressures are good, and pilot burner orifice is not blocked. • Check electrical connections between PC board and pilot operator on gas control. • Check for 24 VAC across PV-MV/PV terminals on PC board. If voltage is okay, replace gas control; if not, replace PC board. NOTE: If PC board goes into lockout, reset system. Lockout is used on L.P.G. models. MAIN BURNER LIGHTS? NO YES • Check for 24 VAC across MV-MV/PV terminals. If no voltage, replace module. • Check electrical connections between PC board and gas control. If okay, replace gas valve or gas control operator, i.e. pilot gas valve, flow switch etc. SYSTEM RUNS UNTIL CALL FOR HEAT ENDS? NO YES CALL FOR HEAT ENDS SYSTEM SHUTS OFF? NO YES TROUBLESHOOTING ENDS NOTE: IF PC board goes into lockout, reset system. • Check continuity of ignition cable and ground wire. NOTE: If ground is poor or erratic, shutdowns may occur occasionally even though operation is normal at the time of checkout. • Check that pilot flame covers flame rod and is steady and blue. • If checks are okay, replace PC board. • Check for proper thermostat (controller) operation. • Remove MV lead at module; if valve closes, recheck temperature controller and wiring; if not, replace gas valve. 45