A.O. Smith GTS-305-NE Service Manual page 44

Component Replacement Instructions
Heat Exchanger
Install Packings and Bracket
26. Install the O-ring (included in kit) over the water outlet tube and the O-ring (included in kit) over the water flow
servo tube. (Figure 45)
27. Install the bracket over the replacement heat exchanger. Push evenly on both sides of the bracket. Attach
with four screws. (Figure 54)
Combine the Heat Exchanger and the Air Intake/Exhaust Assembly
28. Push the heat exchanger into the air intake/exhaust assembly. Attach with four screws. (Figure 51)
29. Attach the cover plate over the air intake passage with 9 screws. (Figure 51)
Install Heat Exchanger and Air Intake/Exhaust Assembly (Figures 48, 49)
30. Attach the fusible link to the back (2 brackets) and side (1 bracket). Slide the assembly into the casing
assembly and attach with 8 screws starting at the top of the water heater.
Connect Pressure Tube and Wire Harness Attachments
31. Connect wire harness attachments.
32. Connect the pressure tube. Attach the ignition line connection with 1 screw. (Figure 47)
Install Burner and Burner Cover Plate (Figure 47)
33. Replace the combustion chamber packing (included in kit) removing any residue from old packing. Insert the
burner and place the burner cover plate into position. Attach the burner cover plate first with 8 screws and
then attach the burner with 2 screws.
Install Gas Manifold and Connect PC Board
34. Make sure that the two black packings (Figure 54) are intact on the
gas control assembly. Attach the gas manifold with 3 machine
screws at the gas control assembly. Replace the lower and upper
packings (included in kit) for the manifold plate removing any residue.
35. Attach the gas manifold with 6 screws at heat exchanger.
36. Attach the ignition line at the burner cover plate.
Connect Water Lines (Figure 45)
37. Attach the PC Board to the heat exchanger with 1 screw.
38. Attach the water outlet line and bracket with 1 screw.
39. Attach the two lines to the bypass servo assembly with 1 screw and 1 bracket for each line.
Install Fan Assembly (Figure 45)
40. Install the fan assembly by inserting the tab on the fan assembly into the slot at the base of the heat
exchanger and attaching with two screws.
41. Push the ducting over the fan assembly exit and secure with the metal pinch clamp.
42. Attach the wire harness to the solenoid on the gas manifold (brown, black wires).
43. Attach the wire harness to the fan assembly (white, yellow, black, red wires).
44. Attach the air temperature thermistor (white, white wires) to the wire harness.
45. Install the front panel using 4 screws.
46. Turn on the water supply, power supply, and gas supply.
47. Check for gas leaks.
On-Demand Gas Tankless Water Heater Service Manual
305i
44
Figure 54