505I - A.O. Smith GTS-305-NE Service Manual

Component Replacement Instructions
Heat Exchanger
1. Turn off the gas supply.
2. Turn off the 120 V power supply.
3. Turn off the water supply. Drain all water
from the appliance.
4. Remove four screws securing the front panel.
Remove front panel.
Remove Fan Assembly (Figure 56)
5. Disconnect wire harness at the fan assembly.
Disconnect the air temperature thermistor
(two white wires) at the connection with the
white and orange wires within the wire
bundle.
6. Pull out the harness attached to the solenoid
on the manifold to make room to pull out the
fan assembly.
7. Remove the 2 screws that attach the fan
assembly to the bottom of the burner.
8. Loosen the ducting from the fan assembly by
pinching open the metal clamp.
9. Pull out the fan assembly.
2 screws
Ducting and
metal clamp
On-Demand Gas Tankless Water Heater Service Manual

505i

45
Figure 55
Burner cover
plate
Gas Manifold
PC Board
Gas Control
Valve
Fan Assembly
Figure 56
Solenoid on the manifold
Wire harness connection
on the fan assembly
Wire harness bundle
(air temperature
thermistor connection to
orange / white wires)