Asme); I (Asme) - 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.
5. Remove the bracket holding the
controller (1 screw). (Figure 76)
6. Disconnect wire harness at the fan
assembly, the electrical connections to
the 3 solenoid valves, and the ignition
line.
7. Remove 3 screws and brackets securing
the water line connections. (Figure 77)
8. Remove the 5 screws that attach the gas
manifold to the combustion chamber
(part of the heat exchanger assembly).
(Figure 77)
9. Remove the 2 screws that attach the gas
manifold to the gas valve. These screws
are machine screws and must be used at
these locations. (Figure 77)
10. Pull out the gas manifold and remove the
connector at the ignitor at the left side of
the gas manifold.
11. Remove the 9 screws attaching the
burner cover plate to the combustion
chamber. (Figure 78)
12. Remove the 2 screws attaching the
burner to the heat exchanger. Pull out
the burner. (Figure 78)
13. Remove the wire harness attachments -
sensors, heating elements, fusible link
brackets. Ensure that the small O-ring at
the thermistor is removed.
On-Demand Gas Tankless Water Heater Service Manual

705i (ASME)

Bracket screw
Figure 76
5 screws
(gas manifold)
Figure 77
Figure 78 9 screws
(burner cover plate)
52
2 machine screws
(gas valve)
Water line connections
2 screws
(burner)