A.O. Smith 110-310-510 – TROUBLESHOOTING

Check all of these basic items before proceeding onto any other section:
o The gas supply valve should be fully open.
o Verify the correct gas type is being used, NG or LP.
o The water supply valve should be fully open.
o The unit should be connected to a 120 VAC 60 Hz power supply. This can be verified by observing the computer board 3?digit LED display. If it is not lit, the computer board is not being powered. Check to see if the ON/OFF switch below the fuse box is set to the on position, or if the fuse in the fuse box is blown.
• REMOTE: If you are using a remote controller, the remote’s power button must be turned on.
• HIGH ALTITUDE: Is your location at an altitude of over 3000 feet? This may cause a lack of air.
See the high altitude procedure in the Troubleshooting Procedures section.
• HARD WATER: What is the hardness of the water? A softener is always recommended, but if the water is above 7 grains of hardness or 70?140ppm, one must be installed. If there is no water softener installed, existing installations will gradually accumulate scale buildup on the heat exchanger and cause a leak. Heat exchanger failures do to hard water scale are not covered under the warranty.
• NEW INSTALLATIONS: Is this installation a few years old or brand new?
o A unit that has worked properly for a while but is now struggling may have become scaled up or contains a dirty burner.
o A new installation most likely is installed or plumbed incorrectly.
• EXTERNAL PROBLEM: Test whether the problem is within the unit or external to the unit (i.e. in the plumbing system) by attempting to run hot water locally through the pressure relief valve
o Does the heater ignite and remain running properly? Or does the heater shut down into an error code? If it runs fine through the PRV the plumbing system is at fault.

NEXT STEP: Finally, check to see if the unit has an error code. The error code will be displayed on the seven segment LED on the bottom left of the computer board. See figures 4 and 5.
• If it is displaying an error code, proceed to the Error Codes section (p. 12).
• If there is no error code, proceed to the General Problems section (p. 8).