NR662 Series Heat Exchanger Replacement
Product Information: NR501, NR662 Series Heat Exchanger
Replacement
The NR501-OD and NR662-OD series heat exchanger replacement is a
procedure only intended for use by a qualified service professional
or authorized Noritz Service Representative. Any unauthorized use
of this manual may result in voiding the warranty. The product is
manufactured by Noritz America Corporation and is located at 11160
Grace Avenue, Fountain Valley, CA 92708. For additional support,
please contact Noritz Technical Support at 866-766-7489.
Procedure
Please follow the steps below to replace the heat exchanger:
Step 1: Remove front cover and disconnect electrical power,
gas, and water
- Remove the front cover
- Disconnect electrical power to unit
- Turn off gas and water
- Remove four screws
- Remove drain two valves and drain the unit completely
- Remove the cover – circuit board
Step 2: Disconnect connectors from the circuit board and remove
the ground wire and circuit board
- Disconnect the connectors from the circuit board
- Remove two ground wires
- Remove the circuit board; there is a screw on the middle-upper
of the circuit board. Let the circuit board hang outside of the
unit
Step 3: Unplug all wires that attach to the wiring harness and
the body of water heater
- Unplug Flame Rod and Ignition Plug
- Loosen the cable tie and unplug the freeze prevention heater,
thermal fuse - Unplug the high limit switch and the thermistor – heat
exchanger - Unplug all wires that attach to the wiring harness except water
servo – main
Step 4: Remove manifold plate
- Remove three big silver screws on the manifold plate that
attach the manifold to the burner - Remove two smaller silver screws from the manifold plate that
attach the manifold to the gas valve - Remove manifold plate and unplug the connector from gas
solenoid valves
Step 5: Disconnect pipes from the water flow sensor and the
water servo – main
- Remove C Clamp
- Remove the water flow sensor
Step 6: Remove the heat exchanger from the case
- Remove the two set screws on the bottom of the burner
- Remove the two set screws on the top of the case (support
bottom of the assembly) - Copper Heat Exchanger(CU HE), Burner, and Fan will come out in
one section. Remove from the unit.
Step 7: Replace CU HE
- Remove ten screws holding the burner to the CU HE
- Separate the burner from the CU HE
Step 8: Remove heat exchanger components from old heat
exchanger and put on new heat exchanger
- The gasket on the front of the exhaust box
- Front side: Freeze prevention heater
- Left side: High limit switch and thermistor – heat
exchanger - Replace new O Ring for the thermistor – heat exchanger
- Attach the thermal fuse and six clamps from four sides of the
heat exchanger. See four views of the heat exchanger to make sure
the thermal fuse is routed correctly - The end of insulation tube(Black) and the clamp on the left are
lined up
NR501, NR662 Series Heat Exchanger Replacement
Model Include: NR501-OD, NR662-OD
This instructional manual is only intended for use by a qualified service professional or authorized Noritz Service Representative. Any unauthorized use of this manual may result in voiding the warranty. Please contact Noritz Technical Support (866-766-7489) for additional support.
SKJ70NL Rev. 10/13
Noritz America Corporation
11160 Grace Avenue, Fountain Valley, CA 92708 Phone 866-766-7489 Fax 714-241-1196
Page 1
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure Procedure
1. Remove the front cover (1) Disconnect electrical power to unit (2) Turn off gas and water (3) Remove 4 screws (4) Remove drain 2 valves and drain the unit completely (5) Remove the cover – circuit board
Diagram
Cover – Circuit Board
2. Disconnect the connectors from the circuit board and remove the ground wire, and the circuit board (1) Disconnect the connectors from the circuit board
(2) Remove 2 ground wires
(3) Remove the circuit board; there is a screw on middleupper of the circuit board. Let the circuit board hang outside of the unit
3. Unplug all wires that attach to the wiring harness and the
body of water heater
(1) Unplug Flame Rod and Ignition Plug (1)
(2) Loosen the cable tie and unplug the freeze prevention
heater, thermal fuse (2)
(2)
(3) Unplug the high limit switch and the thermistor – heat
exchanger
(4) Unplug all wires that attach to the wiring harness
except water servo – main
(3)
(4)
Water Servo – Main
Page 2
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure Procedure
4. Remove the manifold plate (1)
(1) Remove 3 big silver screws on the manifold plate that attach the manifold to the burner
(2) Remove 2 smaller silver screws from the manifold plate that attach the manifold to the gas valve
(3) Remove manifold plate and unplug the connector from gas solenoid valves (3)
(2)
Diagram
(3)
5. Disconnect pipes from the water flow sensor and the water
servo – main
(1)
(1) Remove “C” Clamp (3)
(2) Remove the water flow sensor
(2)
Water Flow Sensor
Page 3
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure
Procedure
6. Remove the heat exchanger from the case
(1) Remove the 2 set screws on the bottom of the burner
(1)
(2) Remove the 2 set screws on the top of the case (support bottom of the assembly)
(3) Copper Heat Exchanger(CU HE), Burner, and Fan will come out in one section. Remove from the unit.
Diagram
(2)
7. Replacing the CU HE (1) Remove 10 screws holding the burner to the CU HE (2) Separate the burner from the CU HE
8. Remove heat exchanger components from old heat
exchanger and put on new heat exchanger
(1)
(1) The gasket on the front of the exhaust box
(2) Front side: Freeze prevention heater
(3) Left side: High limit switch and thermistor – heat
exchanger
(2)
*Replace new O Ring for the thermistor – heat
exchanger (3)
Page 4
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure
Procedure (4) Attach the thermal fuse and 6 clamps from 4 sides of
heat exchanger, See 4 views of the heat exchanger to make sure the thermal fuse is routed correctly
Front side
Diagram
The end of insulation tube(Black) and the clamp on the left are lined up
Right side
Install the thermal fuse(White) inside of the stopper
Back side Keep the thermal fuse straight
Stopper
Left side – 1
Make sure to route the thermal fuse as shown in the diagram to the right (Left side – 1 & 2)
Left side – 2
Page 5
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure Procedure
(5) Place the new freeze prevention heater with one that was shipped in the heat exchanger kit. Wrap the freeze prevention heater around outlet pipe from the CU HE as shown in diagrams
(6) Make sure to route the wire as shown in the diagram (6)
(5)
Outlet Pipe 9. Replace gasket
(1) Remove old burner gasket and replace with new one (1)
Diagram
(6) (6)
10. Place new O Rings on new CU HE (1) Inlet to the CU HE (2) Outlet from the CU HE
(1) (2)
Page 6
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure Procedure
11. Reattach the burner and the CU HE
(1) Attach 10 screws around perimeter of the burner and the CU HE
Diagram
12. Replace the assembly back inside the case (1)
(1) Secure the 2 set screws on the bottom of the burner (2) Secure the 2 set screws on the top of the case
(2)
13. Reconnect water connections (1)
(1) Maintain the high limit switch, the thermistor – heat exchanger, the thermal fuse, and the freeze prevention heater as shown in diagram (1)
(2) Maintain wiring harness as shown in diagram (2)
(3) Insert the outlet pipe to the water servo – main and
attach “C” clamp
Insert the water flow sensor to the inlet water
connection and attach “C” clamp.
And then insert the inlet pipe to the water flow sensor
(3)
and attach “C” clamp.
(2)
Page 7
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure
Procedure 14. Replace the manifold plate
(1) Plug the connector to gas solenoid valves (3) as right diagram
(2) Confirm that there is o-ring before replace the manifold plate
(3) Replace the 2 smaller silver screws from the manifold plate that attach the manifold to the gas valve
(4) Replace the 3 big silver screws on the manifold plate that attach the manifold to the burner
(5) Hand tighten 5 screws equally
(1)
O & BL wire
(2)
Diagram
BK & BL wire
GY & BL wire
(3) (4)
15. Check for water leaks
(1) Replace drain 2 valves
(2) Turn on cold water shut off valve slowly (check for leaks around “C” clamps)
(3) If you get leaks shut off water and re-secure “C” Clamps
Page 8
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure
Procedure
16. Plug all wires that attach to the wiring harness and the body
of the water heater
(2)
(1) Plug all wires that attach to the wiring harness
(2) Tie wires by cable tie as right diagram
(3) Tie wires by cable tie as right diagram
Thermistor – Hot Water
Thermistor – Cold Water
(4) Put the all wires in the position as shown in diagram (4)
Water Flow Sensor
(3) (5) Secure the ground wire
Diagram
Thermistor – Air
Cable Tie Cable Tie
(4) (5)
Page 9
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure
Procedure
(6) Replace the circuit board; secure the screw on middle-
upper of the circuit board.
(6)
Secure the ground wire.
(7) Reconnect the connectors to the circuit board
(8) Plug the high limit switch and the thermistor – heat exchanger
(9) Plug the freeze prevention heater, the thermal fuse (2) and tie the wires by the cable tie
(10) Plug Flame Rod and Ignition Plug.
Left side
Diagram
Confirm that the blue connector is disconnected.
Right side
Take out all wires on the outside of the line
Push the yellow connector.
(10) (9)
(8)
Page 10
NR501-OD, NR662-OD Series Heat Exchanger Replacement Procedure Procedure
(11) Put all wires as the diagram
NR501-OD
NR662-OD
Diagram
(14) Replace the cover – circuit board
24. Check for gas leaks and doing trial operation
(1) Turn on gas
(2) Turn on the unit. Check for leaks around the manifold plate and joining areas. For example – Between Burer and CU HE
(3) If you get leaks shut off gas and water, re-secure leaking points
25. Replace the front cover
(1) Secure the front cover with 4 screws
Cover – Circuit Board
Page 11
