Lochinvar 400 - 801 service manual Flue Temp High, Delta T High, Outlet Temp

Service Manual

3Troubleshooting (continued)

Table 3-4(continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface

FAULT	DESCRIPTION		CORRECTIVE ACTION
		• Inspect the heat exchanger. Reference page 32 of
		this manual for the procedure on how to clean the flue
		side of the heat exchanger.
		• Inspect the flue sensor and associated wiring.
		Measure the resistance of the flue sensor and
Flue Temp High	The stack temperature has exceeded the set	compare to Table 3-2D on page 35 of this manual.
	parameters for the boiler.	Replace the sensor if necessary.
		• Verify that the vent/air intake pipes are properly
		installed and that there are no obstructions.
		• Replace the main control board.
		• 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
		Knight	XL	Installation	and	Operation	Manual
		for the proper piping methods for the Knight XL boiler.
		• Check for 120 vac to the boiler pump motor on a call
Delta T High	The temperature rise across the heat	for heat. If voltage is not present, check the wiring
		back to the main control board. Replace the main
	exchanger has exceeded the set parameters
		control board if necessary.
	for the boiler.
		• If 120 vac is present on a call for heat and the boiler
		pump is not operating, replace the pump.
		• Verify that the boiler pump is set to the proper speed
		or that the pump is the proper size. Reference
		Section	6	- Hydronic	Piping of the		Knight
		XL Installation and Operation Manual for boiler
		pump specifications.
		• 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
Outlet Temp		Knight	XL	Installation	and	Operation	Manual
		for the proper piping methods for the Knight XL boiler.
High	Outlet water temperature has exceeded the
	maximum outlet water temperature.	• Check for 120 vac to the boiler pump motor on a call
		for heat. If voltage is not present, check wiring back
		to the main control board. Replace the main control
		board if necessary.
		• If 120 vac is present on a call for heat and the boiler
		pump is not operating, replace the pump.

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