Lochinvar 399 - 800 Troubleshooting, Check control module fuses, Before troubleshooting

Service Manual

3Troubleshooting

￿WARNING

Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. Always disconnect power to the boiler before servicing. Failure to comply could result in severe personal injury, death, or substantial property damage.

Check control module fuses

NOTICE	ALWAYS check control module fuses
	before replacing control module or any
	major components (blower, etc.). If one of
	these fuses is blown, it can prevent the
	control module or other components from
	operating.

￿WARNING Never jumper (bypass) any device except for momentary testing as outlined in the

Troubleshooting chart. Severe personal injury, death, or substantial property damage can result.

Before troubleshooting:

1.Have the following items:

a.Voltmeter that can check 120 VAC, 24 VAC, and 12 VDC.

b.Continuity checker.

c.Contact thermometer.

2.Check for 120 VAC (minimum 102 VAC to maximum 132 VAC) to boiler.

3.Make sure thermostat is calling for heat and contacts (including appropriate zone controls) are closed. Check for 24 VAC between thermostat wire nuts and ground.

4.Make sure all external limit controls are installed and operating.

Check the following:

1.Wire connectors to control module are securely plugged in at the module and originating control.

2.Gas pressures:

•Maximum: 14 inches w.c. (3.5 kPa) (natural and LP) with no flow (lockup) or with boiler on

• Minimum: 4 inches w.c. (1.0 kPa) (natural), 8 inches w.c. (2.0 kPa) (LP) with gas flowing (verify during boiler startup)

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1.Turn OFF the power to the boiler at the external line switch.

2.Remove top access cover.

3.Remove the control module cover.

4.Inspect fuses F2, F3, F4, and F5, see FIG 3-1 below.

Figure 3-1Control Module Fuses

F3 - 1.25 AMP FUSE

MAIN BOARD

F4 - 3.15 AMP FUSE

GAS VALVE

F5 - 5 AMP FUSE

PUMPS

F2 - 3.15 AMP FUSE

24V SUPPLY

5.The boiler is shipped with three (3) spare fuses in a plastic bag attached to the control module cover.

6.If necessary, replace open fuse (F3 is 1.25 amps, F2 and F4 are 3.15 amps, and F5 is 5 amps).

Note: Fuses F2 - F5 are all slow blow fuses.

￿WARNING Do not jumper fuse or replace with any fuse except as specified. Failure to comply

could result in severe personal injury, death, or substantial property damage.

7.Install control module cover and top access cover after fuse inspection.

8.Restore power to the boiler at the external line switch and verify boiler operation (Section 10 - Start-up in the Knight Boiler Installation and Operation Manual) after completing boiler service.