Component Replacement Instructions
Disconnect PC Board (Figure 39)
11. Remove 1 screw connecting the PC
Board to the heat exchanger
assembly.
12. Remove the 6 screws that attach the
gas manifold to the combustion
chamber (part of the heat exchanger
assembly).
13. Remove the 3 screws that attach the
gas manifold to the gas valve. These
screws are machine screws and must
be used at these locations.
Remove Gas Manifold (Figure 39)
14. Pull out the ignition line and remove the gas manifold.
15. Remove the 8 screws attaching the burner cover plate to the combustion chamber. Move the cover
plate to the side. It is not necessary to disconnect the wire harness from the burner cover plate.
16. Remove the 2 screws attaching the burner to the heat exchanger. Pull out the burner.
17. Unscrew the ignition line connection. (Figure 40)
18. Remove the wire harness attachments - sensors, heating elements, fusible link brackets. Ensure
that the small O-ring in the thermistor is removed.
19. Remove 3 screws behind the fan. (Figure 41)
Disconnect Wire Harness Attachments and Screws Holding the Heat Exchanger
Ignition line
6 screws (gas manifold)
PC Board screw
(gas valve)
Figure 39
Ignition line
connection
8 screws
(burner cover plate)
2 screws (burner)
Figure 40
Remove Burner and Burner Cover Plate (Figure 40)
Figure 42
2 screws
Figure 41
3 screws
On-Demand Gas Tankless Water Heater Service Manual
39
Heat Exchanger
505e/o
3 machine screws
