Maintenance; Rod Assembly - A.O. Smith 110 Troubleshooting Manual

6. MAINTENANCE
Become familiar with the components before attempting these procedures, utilizing the Installation
Manual and referencing the component schematic on the last few pages of the manual.
Safety is the most important part of this guide. These procedures must be done by a licensed competent
technician. A.O. Smith is not liable for the actions of the technician if he/she fails to adhere to any or all
safety procedures, specifically in regards to electrical and gas safety.
1) TOOLS ‐ Gather the following materials together:
a. Sheet of 100 Grit Sandpaper
b. #2 Philips Screw Driver
c. Flashlight
2) POWER ‐ Disconnect power to your unit by either unplugging it from the wall outlet, or by the circuit
breaker, depending on the setup. The 3‐digit LED on the PCB should not be lit.
3) FRONT COVER ‐ Remove the front cover. It is
held on by two screws on the top corners of the
tankless unit.
4) ROD ASSEMBLY –
a. Locate the black, yellow, and orange wires
located in the center of the unit.
b. Remove the three Phillips head screws
holding the panel in place.
c. Pull the assembly out. Caution, all pieces
are separate. Be careful to not lose the
sight glass.
5) SENSORS – It is important to be very gentle with the sensors while cleaning them, as they will easily
bend out of place. Their original position relative to the burner needs to be unaltered to function
properly.
a. Clean the flame sensor with 100 grit sandpaper, thoroughly to a bright finish.
b. Clean the air fuel ratio rod with 100 grit sandpaper, thoroughly to a bright finish.
6) REASSEMBLE ‐ Reassemble the unit in reverse order – sight glass, gasket, rods, and metal cover. Key
points to remember:
a. Connect all 3 wires on front of burner.
b. Inspect all of the gaskets.
CLEANING THE ROD ASSEMBLY
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Figure 24
Troubleshooting Guide