Mini-Therm II Hydronic Boiler
Page 19
Troubleshooting Honeywell S8600
Intermittent Pilot System
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
Note: Before troubleshooting, familiarize yourself with the start-up and
checkout procedure.
Check line voltage power, low voltage transformer, hi- limit switch,
thermostat (controller) and wiring.
Pull ignition lead and check spark at module.
Spark okay?
• 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 module and pilot operator on gas
control.
• Check for 24 Vac across PV-MV/PV terminals on module. If voltage is
okay, replace gas valve; if not, replace module.
Note: If S8600H goes into lockout, reset system. Lockout is used on
L.P.G. models.
• Check continuity of ignition cable and ground wire.
• Clean flame rod.
• Check electrical connections between flame rod and module.
• Check for cracked ceramic flame rod insulator.
• Check that pilot flame covers flame rod and is steady and blue.
• Adjust pilot flame.
• If problem persists, replace module.
• Check for 24 Vac across MV-MV/PV terminals. If no voltage, replace
module.
• Check electrical connections between module and gas valve. If okay,
replace gas valve.
Note: If S8600H 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 module.
• Check for proper thermostat (controller) operation.
• Remove MV lead at module; if valve closes, recheck temperature
controller and wiring; if not, replace gas valve.
Repeat procedure until trouble-free operation is obtained.
Start
Turn off gas supply.
Turn thermostat
(controller) to call for
heat.
Power to module
(24V nominal).
Spark across igniter/
sensor gap.
Turn gas supply on.
Pilot burner lights?
Spark stops when pilot
is lit?
Main burner lights?
System runs until call for
heat ends?
Call for heat ends.
System shuts off?
Troubleshooting ends
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