Service Manual
3Troubleshooting (continued)
Table
FAULT | DESCRIPTION |
| CORRECTIVE ACTION |
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| • Reset the pressure switches. |
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| • Measure the supply gas pressure to determine cause | |||||||||
Gas Pressure SW |
| of failure. Natural gas pressures should be between | |||||||||
| 4 - | 14 | inches | w.c. | and | LP gas | pressures | ||||
(will require a manual |
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| should be between 8 - 14 inches w.c. |
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reset once the condition | Either the optional manual reset low gas |
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has been corrected. Press | pressure switch or the optional manual reset | • Refer to Section 7 - Gas Connections of the Knight | |||||||||
the RESET button on the | high gas pressure switch tripped. | XL Installation and Operation Manual for detailed | |||||||||
SMART SYSTEM display |
| information concerning the gas supply. |
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to reset.) |
| • Correct the supply gas pressure if necessary. |
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| • Check for a loose or misplaced jumper if pressure | |||||||||
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| switches are not installed. |
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| • Check boiler pump operation on a call for heat. |
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Flow |
| • Check for closed valves or obstructions in the boiler | |||||||||
| piping. |
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Switch/LWCO | Either the optional flow switch or the optional |
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• Verify | system is | full of | water | and all air has been | |||||||
(will require a manual | low water cutoff is not making. | ||||||||||
purged from the system. |
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reset once condition has |
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been corrected. Press the |
| • Check for loose or misplaced jumpers if flow switch or | |||||||||
RESET button on the |
| LWCO is not installed. |
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SMART SYSTEM display |
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| • Replace fuse F3 on the control board, see page 33 | ||||||||||
to reset.) | Blown fuse. | ||||||||||
| of this manual. |
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Blocked Drain SW | The blocked drain switch has detected | • Check condensate tube from unit to floor drain for | |||||||||
(will require a manual | excessive condensate build up inside the | proper installation and obstructions. |
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unit. | • Inspect condensate trap for blockage. | Clean | if | ||||||||
reset once condition has | |||||||||||
been corrected. Press the |
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RESET button on the |
| • Check for loose wiring connection at wire harness | |||||||||
SMART SYSTEM display |
| plug. |
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to reset.) |
| • Bad blocked drain switch. Replace switch. |
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| • Check the wiring connections to switch. Wires should | |||||||||
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| be connected to the common and normally closed | |||||||||
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| terminals. |
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| • Air intake lengths exceed the maximum allowed | |||||||||
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| lengths. Refer to Section 3 - General Venting of the | |||||||||
APS |
| Knight | XL | Installation | and | Operation | Manual | for | |||
| proper lengths. |
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Open |
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| • Check | for | obstruction | or | blockage | in the | air | ||||
(will require a manual |
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| intake pipes or at terminations. |
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reset once the condition |
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Air pressure switch contacts are open. | • Check reference hoses connected to the air pressure | ||||||||||
has been corrected. Press |
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the RESET button on the |
| switch for blockage or obstruction. |
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SMART SYSTEM display |
| • Inspect the burner. Reference page 31 of this manual | |||||||||
to reset.) |
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| for removal and cleaning procedures. | Replace if | |||||||||
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| • Inspect the heat exchanger. Reference page 32 of | |||||||||
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| this manual for removal and cleaning procedures. | |||||||||
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| Replace if necessary. |
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| • Faulty air pressure switch. Replace switch. |
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37
