Lochinvar 399, 999 - 750 Diagnostic Status Indication, Access to Internal Control Panel, Table-U

Hydronic Heating Boilers and Domestic Water Heaters

OPERATION Continued

Diagnostic Status Indication

The ignition module has an LED which indicates the status of the safety circuits. A remote Ignition Module Status indicating light(s) is wired from the ignition module Status LED and mounted on the front control panel. The flashing operation of these light(s)/LED indicates the diagnostic status of the ignition control module. The status LED, mounted on the ignition module, flashes a code sequence from the Ignition Module to indicate the status of the ignition process. See TABLE–U, this page for the flashing diagnostic status codes as signaled by the ignition module.

Access to Internal Control Panel

The control panel is accessed by turning the mounting screw located at the bottom center of the exterior control panel. Pull the panel out at the bottom. The door will tilt into unit until it comes free from the outer top. The outer control panel has an overlay attached to the exterior surface which indicates the function of

each of the boiler’s indicating lights and a clear window to view the digital temperature display from the electronic temperature control. The thermostat and diagnostic light board are mounted to the back of the control panel door.

The control panel assembly is mounted on a slide out chassis to allow easy access to the components on the panel. The control panel contains the ignition module, transformer for the 24 VAC control circuit, circuit breaker for the control circuit, switching relays for component operation and wiring harness connections to the unit’s components. The control panels are common and may be switched between units for troubleshooting.

Removing the Control Panel

1.Pull the control panel out as far as it will go.

2.Remove the multi-pin connector blocks from the top and right side of the control panel.

3.Use a 1/2" box wrench or socket wrench to remove the bolt on the right side of the control panel.

4.Remove the entire control panel.

5.Reinstall the control panel in the reverse order.

	TABLE-U
	Ignition Control Diagnostic Codes
Code Sequence	Condition
Constant ON	System OK, no faults present.
Constant OFF	Possible control fault, check power; LED may be effective,
	do not replace control if all operational sequences function
	properly, see TroubleShooting Guide.
One Flash	Low Air, check air pressure switch and hoses to pressure
	sensing points, fan, venting and sealing of pressurized
	chamber. Note: Brief flashing normal on fan start-
	up/proving.
Two Flashes	Flame without call for heat, check for a gas valve stuck in
	the open position, air, venting, burners and the combustion
	process. Fan will remain on.
Three Flashes	Lockout due to flame failure, push reset button on inner
	control panel after correcting ignition problem. Initial heater
	start up without properly bleeding air from the gas line may
	require multiple reset functions to achieve proper ignition.
Four Flashes	Igniter failure, igniter will not maintain minimum 2.75 amp
	current draw, caused by low voltage, bad wiring/continuity,
	high resistance or igniter failure.
Five Flashes	Power supply problem, check for low supply voltage or
	transformer output less than 18VAC.
Six Flashes	Replace ignition module, internal fault.

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