Component Replacement Instructions
705e/o (ASME)
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. Disconnect wire harness at the fan
assembly, the electrical connections to
the 3 solenoid valves, and the ignition
line.
6. Remove 3 screws and brackets securing
the water line connections. (Figure 68)
7. Remove the 5 screws that attach the gas
manifold to the combustion chamber
(part of the heat exchanger assembly).
(Figure 68)
8. 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 68)
9. Pull out the gas manifold and remove the
connector at the ignitor at the left side of
the gas manifold.
10. Remove the 9 screws attaching the
burner cover plate to the combustion
chamber. (Figure 69)
11. Remove the 2 screws attaching the
burner to the heat exchanger. Pull out
the burner. (Figure 69)
12. Remove the wire harness attachments -
sensors, heating elements, fusible link
brackets. Ensure that the small O-ring at
the thermistor is removed.
13. Remove the 4 screws connecting the
heat exchanger to the casing. (Figure 70)
14. Pull out the assembly. Remove the
brackets on the side and back holding
the fusible link. Slide off the fusible link.
9 screws
(burner cover plate)
2 screws
(burner)
Figure 69
Water line connections
Figure 68
5 screws
(gas manifold)
2 machine screws
(gas valve)
Figure 70 Bottom screws
Top screws
Heat Exchanger
On-Demand Gas Tankless Water Heater Service Manual
50