CAUTION
IF HEAT EXCHANGER MAINTENANCE REQUIRES TUBING REPLACEMENT, SPECIAL PROVISIONS SHALL BE TAKEN TO ENSURE THAT THE DAMAGED TUBES ARE CAREFULLY REMOVED.
REPLACEMENT TUBES MUST BE PROPERLY INSTALLED AND EXPANDED INTO THE ROLLED TUBE TUB.
REPLACEMENT PARTS
Replacement parts may be ordered through A. O. Smith dealers, authorized servicers or distributors. Refer to the Yellow Pages for where to call or contact (in United States) the A. O. Smith Water
Products Company, 5621 West 115th Street, Alsip, IL 60803,
For Technical Assistance call A. O. Smith Technical Information Center at
TROUBLESHOOTING
Before any extensive troubleshooting, ensure that:
•Power (120 VAC) is supplied to the appliance.
•System control (tank probe, thermostat, etc.) is calling for appliance operation (call for heat).
•Other contacts (switches) are closed (low water cutoff, flow switch, limit controls, pressure switches, etc.)
•Gas supply pressure is within the maximum and minimum operating ranges listed on the appliance rating plate/label.
•Appliance is wired according to wiring diagram.
NOTE: Shorting the thermostat wiring to ground in the 24 volt circuit will blow the 3 amp fuse.
•All wire terminals/connectors are firmly attached to valves, modules, switches, limit controls, etc.
•There has been no damage caused by freezing, inoperative pumps, etc.
CAUTION
MAKE SURE POWER IS DISCONNECTED FROM MAIN BREAKER BEFORE SERVICING.
CAUTION
LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN SERVICING CONTROLS. WIRING ERRORS CAN CAUSE IMPROPER FUNCTIONING OF UNIT RESULTING IN PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.
TROUBLESHOOTING IGNITION SYSTEM
The control system has several features to aid in troubleshooting problems which may occur during operation. If a fault occurs, the
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Display Board contains sixteen (16) red fault LED indicators to help pinpoint the source of failures. In addition, the display will inform the user on which stage the failure occurred by illuminating a red Stage LED. In cases where the problem persists to lockout, the appropriate red LEDs will remain illuminated and a three digit error code will flash on the display screen. A summary of error codes is given in table 19. The error codes are broken into two categories: hard lockouts and soft lockout.
Hard Lockouts:
Hard lockouts require a manual reset accomplished by pressing the Enter/Reset
Soft Lockouts:
Soft Lockouts also require a manual reset accomplished by pressing the Enter/Reset
A description of the red fault LEDs and their corresponding functions are as follows.
LED | Controller Function |
Blocked Flue | Indicates a blockage or interference at the |
| appliance flue. |
Temp. Probe Fail | Indicates failure at one of the temperature |
| probes. Unit will |
| probe fails. |
Insufficient Air | Indicates air pressure was too low to create |
| a sufficient differential to close the |
| differential pressure switch. |
Circulate Fail | Indicates water flow was too low to close |
| the flow switch. |
Gas Valve Fail | Monitors Gas Valve relay output. LED is ON |
| when the output relay supplying power to |
| the gas valve(s) is open. |
High Limit | Monitors ECO in the Outlet Temperature |
| probe. LED is ON when the ECO is open. |
Flame Fail | Monitors the Flame Sense Rod. LED is ON |
| when a signal from the flame rod is not |
| sufficient to indicate flame. |
Igniter Fail | Indicates igniter current was too low to meet |
| minimum value which allows trial for |
| ignition to continue. |
Low Gas Fail | Inlet gas pressure is not sufficient to close |
| gas pressure switch. |
High Gas Fail* | Manifold gas pressure is has exceeded |
| designed maximum value. |
LWCO Fail* | Indicates water level in system is too low for |
| safe operation. |
Power Vent Fail* | Air pressure at Power Vent Switch is not |
| sufficient for safe operation. |
*Optional Equipment - LEDs will illuminate only if equipment is connected to boiler.
Upon lockout, manually push the ENTER/RESET button on the display panel to restart the boiler.
Verify proper operation after servicing.