Service Manual

3 Troubleshooting

Table 3-1Troubleshooting Chart - No Display

FAULT

CAUSE

 

CORRECTIVE ACTION

 

 

 

 

 

 

 

- No 120 vac supplied to unit.

Check external line switch, fuse, or breaker.

 

 

Check position of ON/OFF switch. Turn switch to the

 

 

 

 

 

ON position.

 

 

 

 

 

 

 

 

 

• Check 120 vac through the ON/OFF switch.

 

 

 

• Check wiring

harness connection

between

display

 

 

 

board

and

main

control

board.

Connect

No Display

 

 

harness at both points.

 

 

 

 

 

- No voltage through the switch.

Replace switch.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Bad display board.

Replace board.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Bad main control board.

Replace the main control board.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Blown fuse.

Replace

fuse

F3 on

the main

control

board, see

 

 

page 33 of this manual.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Main control board temperature set point

Review temperature setting.

 

 

 

 

 

 

satisfied.

 

 

 

 

 

 

 

 

 

 

 

- Remote thermostat satisfied.

Review remote thermostat setting.

 

 

 

 

 

 

 

 

 

 

 

 

No Burner

- Outside air temperature above Warm

Check

location of

outside

air

sensor.

Check

Weather Shutdown (WWSD) set point for

 

resistance of outdoor air sensor and compare to Table

Operation

main control board.

 

3-2B on page 35 of this manual.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Consult

display for

specific

fault.

Refer

to fault

 

- Unit locked out on fault.

 

descriptions on page 37 of this manual for corrective

 

 

 

actions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Unit in Shutdown Mode.

• Take unit out of Shutdown Mode.

 

 

 

 

 

 

 

 

 

 

Check ramp delay parameter settings. Optional PC

 

- Ramp delay active.

 

software required.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Turn ramp delay feature off.

See page 22 of this

 

 

Unit Does

 

 

manual for instructions on how to turn this feature off.

 

 

 

 

 

 

 

 

 

 

 

 

• Check BMS parameter settings. Optional PC

Not Modulate

- Boiler controlled by BMS.

 

software required.

 

 

 

 

 

 

Above 50%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Verify that the flue sensor is located in the flue outlet.

 

 

 

 

 

 

 

 

- Flue sensor open.

Check wiring connections at the flue sensor.

 

 

 

 

 

 

 

 

 

 

 

 

 

Check the resistance of the flue sensor and compare

 

 

 

 

 

to Table 3-2D on page 35 of this manual.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

34

Page 34
Image 34
Lochinvar 400-801 service manual No Display, No Burner, Operation, Unit Does, Not Modulate, Above 50%

400-801 specifications

The Lochinvar 400-801 is a high-efficiency commercial boiler that embodies advanced engineering and cutting-edge technology. Designed for a variety of commercial applications, this boiler is known for its reliability, efficiency, and robust performance.

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