Noritz Nrc711 Series Heat Exchanger Replacement Instruction Manual

NRC711 Series Heat Exchanger Replacement

Product Information

The NRC661A and NRC711 Series are heat exchangers manufactured
by Noritz America Corporation. These models include NRC661A-DV,
NRC661A-OD, NRC711-DV, and NRC711-OD.

This instructional manual provides detailed information on how
to replace the heat exchanger. It is intended for use by qualified
service professionals or authorized Noritz Service Representatives.
Unauthorized use of this manual may result in voiding the warranty.
For additional support, please contact Noritz Technical Support at
866-766-7489.

Product Usage Instructions

Before starting the replacement procedure, disconnect the
electrical power, turn off gas and water, and remove the front
cover and drain valves from the unit. Follow the steps below to
replace the heat exchanger:

Step 1: Remove the Cover – Circuit Board

1. Remove the four screws and drain unit completely.
2. Disconnect the connectors from the circuit board and remove the
   ground wire.
3. Remove the circuit board by unscrewing two screws, one on the
   right-side and middle-upper of the circuit board. Let the circuit
   board hang outside of the unit.

Step 2: Unplug All Wires

1. Unplug Flame Rod and Ignition Plug.
2. Unplug all wires that attach to the wiring harness except for
   the water servo – main.
3. For DV model only, unplug the freeze prevention heater and
   thermistor-exhaust. Release the wire clamps.

Step 3: Remove the Manifold Plate

1. Remove the three big silver screws on the manifold plate that
   attach the manifold to the burner.
2. Remove the two smaller silver screws from the manifold plate
   that attach the manifold to the gas valve.
3. Remove the manifold plate and unplug the connector from gas
   solenoid valves.

Step 4: Disconnect Water Pipes

1. Remove the C Clamp and water flow sensor.
2. Make sure to feed the wires from the water servo main around
   the outlet water pipe as shown in the diagram.

Step 5: Remove Exhaust Flue and Drain Hose

1. For DV model only, disconnect the venting from the unit and
   remove the exhaust flue from the top of the unit.
2. Remove the drain hose from Stainless Steel Heat Exchanger (SS
   HE).

Step 6: Remove the Cover and Route Wires

1. Remove the cover – water level electrode from the condensate
   container.
2. Unplug the water level electrode wiring, the high limit switch,
   and the thermistor – heat exchanger wiring harness as shown in the
   diagram.

After completing these steps, the heat exchanger replacement
procedure is complete.

NRC661A, NRC711 Series Heat Exchanger Replacement
Model Include: NRC661A-DV, NRC661A-OD, NRC711-DV, NRC711-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.

SKJ70RF Rev. 10/13

Noritz America Corporation
11160 Grace Avenue, Fountain Valley, CA 92708 Phone 866-766-7489 Fax 714-241-1196

Page 1

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure Procedure
1. Remove the front cover (1) Disconnect electrical power to the unit (2) Turn off gas and water (3) Remove 4 screws (4) Remove drain 2 valves and drain unit completely (5) Remove the cover – circuit board
Cover – Circuit Board

Diagram

2. Disconnect the connectors from the circuit board and remove the ground wire, the circuit board (1) Disconnect the connectors from circuit board
(2) Remove the ground wire DV model; 3 ground wires OD model; 2 ground wires
(3) Remove the circuit board; there are 2 screws, one on the right-side and middle-upper of the circuit board. Let the circuit board hang outside of the unit

OD model has only a screw of the upperside

3. Unplug all wires that attach to the wiring harness and the body of the water heater (1) Unplug Flame Rod and Ignition Plug

(2) Loosen the wire anchor from right side of the case and

unplug the freeze prevention heater, thermal fuse (2)

(3) Unplug all wires that attach to the wiring harness

except the water servo – main

(4) *DV model only

Unplug the freeze

prevention heater,

the thermistor

– exhaust.

Release the wire clamps

(4)

Wire clamp (3)

(1)

(2)

Water Servo – Main

Page 2

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure Procedure
4. Remove the manifold plate (1) Remove 3 big silver screws on the manifold plate that (1) 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 the manifold plate and unplug the connector from gas solenoid valves (3)
(2)

Diagram

(3)

5. Disconnect water pipes from the water flow sensor and the

water servo – main

(1) Remove “C” Clamp (3)

(1)

(2) Remove the water flow sensor

(3) Make sure to feed the wires from the water servo main around the outlet water pipe as shown in bottom diagram

Wiring harness

(2,3)

Water Flow Sensor

Page 3

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure 6. Remove the exhaust flue from top of the unit *DV model
only(1) Disconnect the venting from the unit
(2) Remove 4 screws and pull the flue off of the unit and set aside

Diagram

7. Remove the drain hose from Stainless Steel Heat

Exchanger(SS HE)

(1)

(1) Remove 1 spring clamp

(2) Remove the drain hose from SS HE and pull the hose out as shown in the right diagram (2)

(2)

8. Remove the cover and route wires – water level electrode (1)
(1) Remove the cover – water level electrode from the
condensate container

(2) Unplug the water level electrode wiring, the high limit switch and the thermistor – heat exchanger wiring harness as shown in diagram (2)

(3) Make sure to feed the wires from the water level

electrode wiring harness outside the case as shown in

diagram (3)

(2)

(3)

Page 4

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure 9. Remove the heat exchanger from the case
(1) Remove the 2 set screws on the bottom of the burner (1)
(2) Remove the upper left and right set screws near the top of the case (In OD Model, the screws will be at the top of the case) (support bottom of assembly)
(3) SS HE, Copper Heat Exchanger(CU HE), Burner, and Fan will come out in one section. Remove from the

Diagram

(2) DV model

10. Separate the SS HE from the CU HE

(1) Remove 2 screws on the bracket between the SS HE

(1)

and the CU HE

(2) Remove the 3 screws that located on the back side of

the SS HE

(3) Remove “C” clamp

(4) Separate the SS HE from the CU HE

(2)

(3)

(2) OD model

Page 5

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure

Procedure

11. Replacing the SS HE

Note: If you are not replacing the SS HE then you can skip this

(1)

step and set the SS HE aside.

(1) Remove old gasket between the SS HE and the CU HE

Exhaust Box and replace with new one

(2) *OD model only

Remove the gasket on the front of the SS HE and place

on new one

Diagram

(2) OD model only

12. Replacing the CU HE (1) Remove 10 screws holding the burner to the CU HE (2) Separate the burner from the CU HE

13. Remove heat exchanger components from old heat exchanger and put on new heat exchanger (1) Front side: Freeze Prevention Heater
(2) Left side: High limit Switch and Thermistor – Heat Exchanger *Replace new O Ring fot the thermistor – heat exchanger

Page 6

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure (3) Attach the thermal fuse and 5 clamps from 4 sides of
the heat exchanger, See 4 views of the heat exchanger to make sure the thermal fuse is routed

Right side

Install the thermal fuse(White) inside of the stopper

Diagram

The end of insulation tube(Black) and the front of the heat exchanger are lined up
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

Front side

Page 7

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure
(4) *DV model only Place the new freeze prevention heater with one that was shipped in the heat exchanger kit. Wrap the freeze prevention heater around inlet pipe to the CU HE.

Diagram Left side of HE

14. Replace gaskets (1)
(1) Remove old burner gasket and replace with new one

15. Place new O Rings on new CU HE (1) Inlet to the CU HE (2) Outlet from the CU HE

(1)

(2)

Page 8

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure
16. Reattach Burner, CU HE, and SS HE (1)
(1) Attach the inlet pipe to the CU HE with the “C” Clamp. Make sure to insert the pipe in all the way before attaching “C” Clamp.
(2) Attach 3 screws that located on the back side of the SS HE to hold the SS HE to the CU HE
(3) Attach 2 screws on the bracket between the SS HE and the CU HE
(4) Attach 10 screws around perimeter of the burner and the CU HE
(2)

Diagram

(3)

(4)

17. Replace the assembly back inside the case

(1) Secure the 2 set screws on the bottom of the burner

(1)

(2) Secure the upper left and right set screws near the top of the case (In OD model, the screws will be at the top of the case)

(2) DV model

(2) OD model Page 9

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure Procedure
18. Replace the flue from top of the unit *DV model only (1) Attach the flue to the unit and secure the 4 screws (2) Reconnect the venting to the unit

Diagram

19. Reconnect water connections
(1) Maintain the high limit switch, the thermistor – heat exchanger and the water level electrode wiring harness as shown in diagram (1)
(2) *DV model only Maintain the freeze prevention heater and the thermistor – exhaust wiring harness as shown in
(3) Maintain wiring harness as shown in diagram (3)
(4) Insert the pipe from the CU HE to the water servo main and attach “C” clamp
(5) Insert the water flow sensor to the inlet water connection and attach “C” clamp. And then insert the water inlet pipe to the water flow sensor and attach “C” clamp. (3)

(2)
(1) (4)

20. Replace the drain hose to the SS HE
(1) Replace the drain hose to the SS HE and reattach 1 spring clamp as right diagram (1)

(5) (1)

Page 10

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure
Procedure
21. 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 2 smaller silver screws from the manifold plate that attach the manifold to the gas valve
(4) Replace 3 big silver screws on the manifold plate that attach the manifold to the burner
(5) Hand tighten 5 screws equally

Diagram (1)
O & BL wire BK & BL
wire (2)

GY & BL wire

(3) (4)

22. 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 11

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure

Procedure

23. 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 the cable tie as right diagram

(3) Tie wires by the cable tie as right diagram

Thermistor – Hot Water Water Flow Sensor

(4) Put the all wires in the position as shown in diagram (4)

(3) (5) Secure the ground wire

Diagram Thermistor – Air
Thermistor Cold Water
Cable Tie

Cable Tie

(4)

(5)

Cable Tie (OD model only)

Page 12

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure

Procedure
(6) Replace the circuit board; secure 2 screws, one on the right-side and middle-upper of the circuit board. Secure the ground wire. DV model; 2 ground wires OD model; 1 ground wires

Diagram
(6) OD model has only a screw of the upperside

(7) Reconnect the connectors to the circuit board

(8) Plug the freeze prevention heater, thermal fuse (2) and the tie it by wire anchor to right side of the case as right diagram
(9) Plug Flame Rod and Ignition Plug

(10) *DV model only

Plug the freeze prevention heater, the thermistor –

exhaust. Secure the wire by clamps (2) as shown in

diagram (10)

Confirm that the blue

Left side

connector is disconnected.

Right side (DV model)

Take out all wires from the left side of the line

Right side (OD model)

Push the yellow connector.

(9)

(8)

(10) Wire clamp
Page 13

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure

Procedure

(11) Replace the cover – water level electrode to the

condensate container

(11)

(12) *DV model only

Reinstall power supply cord as right diagram

(13) Put all wires as the diagram

Diagram

(12)

OD model

DV model

Page 14

NRC661A, NRC711 Series Heat Exchanger Replacement Procedure Procedure
(14) Replace the cover – circuit board

Diagram

24. Check for gas leaks and doing trial operation
(1) Turn on gas
(2) Turn on the unit. Check for leaks around manifold plate and joining areas. For example – Between the burer and the CU
(3) If you get leaks shut off gas, water and re-secure leaking points
25. Replace the front cover
(1) Secure the front cover with 4 screws

Cover – Circuit Board

Page 15