Lochinvar Water Heater Manual and Automatic Reset High Limit Troubleshooting

Service Manual

3 Troubleshooting

Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface

FAULT	DESCRIPTION		CORRECTIVE ACTION
			Automatic Reset High Limit:
			• Verify that the system is full of water and that all air
			has been properly purged from the system.
			• Verify that the boiler is piped properly into the heating
			system. Refer to Section 6 - Hydronic Piping of the
			SYNC Installation and Operation Manual
			for the proper piping methods for the SYNC.
			• Check voltage to boiler pump motor on a call for
			heat. If voltage is not present, check wiring back to
			the pump relay.
			• Replace the pump relay if necessary.
			• If 120 VAC is present on a call for heat and the boiler
			pump is not operating, replace the pump.
Automatic Reset			• If the system pump is a variable speed pump, ensure
High Limit / HEX-			that the system flow is not less than the boiler flow.
Temp SW	Either the auto-reset high limit (optional),		• If operating on either an inlet or system supply
(will require a manual
reset once the condition	or the O-temp heat exchanger switch as		sensor, check temperature setting of the main control
			board.
has been corrected. Press	opened.
			• If the high limit has tripped, check setting of the
the RESET button on the
display to reset.)			device.
			• Check resistance of water sensors and compare to
			Table 3B on page 45 of this manual. Replace sensor
			if necessary.
			• Replace high limit.
			HEX Temp SW:
			• Check continuity across two contacts. Wires should
			be connected at both poles of normally closed switch.
			• Inspect the rear of the inner combustion chamber
			at the burner level, for refractory breakdown/missing.
			Replace the refractory if no damage to the heat
			exchanger as a result of the burner, otherwise,
			replace the heat exchanger.
			• Faulty O-temp heat exchanger switch. Replace
			switch.
			• Vent/air intake lengths exceed the maximum allowed
			lengths. Refer to Section 2 - General Venting of the
			SYNC Installation and Operation Manual for
Blower RPM’s	The actual fan rpm is 30% lower than what		proper lengths.
			• Check for obstruction or blockage in the vent/air
Too Low	is being called for.	Reference the Burners
	Screen information	on page 32 of this	intake pipes or at terminations.
(will require a manual			• Check the wiring connections at the fan and at the
	manual.
reset once the condition
has been corrected. Press			main control board.
			• Replace the fan.
the RESET button on the
display to reset.)			• Replace the main control board.
	Blown fuse.		• Replace fuse F4 on the control board, see page 43 of
			this manual.

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