Service Manual
3Troubleshooting (continued)
Table 3A Troubleshooting 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 | |
|
|
| harness at both points. |
|
|
| ||
No Display |
|
|
|
|
|
|
|
|
- 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 24 of this manual. |
|
|
| ||
|
|
|
|
|
| |||
| - Main control board temperature set point | • | Review temperature setting. |
|
| |||
| satisfied. |
|
|
|
|
|
|
|
No Burner |
|
|
|
|
| |||
- Remote thermostat satisfied. | • | Review remote thermostat setting. |
|
| ||||
Operation |
|
|
|
|
|
|
|
|
|
| • | Consult display for specific fault. | Refer | to fault | |||
| - Unit locked out on fault. |
| descriptions on pages 28 - 35 of this manual for | |||||
|
|
| corrective actions. |
|
|
| ||
|
|
|
| |||||
| - Water heater controlled by BMS. | • | Check BMS parameter settings. Optional PC software | |||||
|
| required. |
|
|
|
| ||
|
|
|
|
|
|
| ||
Unit Does Not |
|
|
| |||||
- Flue sensor open. | • | Verify that the flue sensor is located in the flue outlet. | ||||||
Modulate Above |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
50% |
| • | Check wiring connections at the flue sensor. |
| ||||
|
|
| ||||||
|
| • Check the resistance of the flue sensor and compare | ||||||
|
|
| to Table 3D on page 26 of this manual. |
| ||||
|
|
|
|
|
|
|
|
|
25 
