Heat Exchanger Replacement Procedure; 1. Remove Front Cover; 2. Remove Circuit Board; 3. Unplug All Wires - Noritz NR50 Series Instructional Manual

NR50, NR66, and NR71 Heat Exchanger Replacement Procedure
Procedure

1. Remove front cover

(1) Disconnect electrical power to unit
(2) Turn off gas and water
(3) Remove 4 screws
(4) Remove filter and drain unit
completely

2. Remove circuit board

(1) Remove 1 screw that holds the circuit
board and let it hang outside of the
unit
3. Unplug all wires that attach to the wiring
harness and the body of the water heater
(1) Flame rod and ignition plug
(2) Freeze prevention heater, thermal
fuse (2), high limit switch
(3) Igniter plug
(4) Freeze prevention sensor
Note: The NR50 doesn't have freeze prevention
standard, but can be added as an option.

4. Remove manifold plate

(1) Remove the 4 big silver screws on the
manifold plate that attach the
manifold to the burner
(2) Remove the 3 smaller gold screw from
the manifold plate that attach the
manifold to the gas valve
(3) Remove manifold plate
Diagram
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