NORITZ NRC711 Series Heat Exchanger Replacement Instruction Manual

NORITZ 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 the 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 the 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 the middleupper of the circuit board. Let the circuit board hang outside of the unit.

Step 2: Unplug All Wires

1. Unplug the Flame Rod and Ignition Plug.
2. Unplug all wires that attach to the wiring harness except for the water servo-main.
3. For the 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 the 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 the Exhaust Flue and Drain Hose

1. For the 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 Procedure

4.  Remove the manifold plate

(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 the manifold plate and unplug the connector from the gas solenoid valves (3)

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5.  Disconnect water pipes from the water flow sensor and the water servo – main

(1)   Remove “C” Clamp (3)

(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

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Procedure| Diagram
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6.  Remove the exhaust flue from top of the unit *DV model

(1)  Disconnect the venting from the unit

(2)  Remove 4 screws and pull the flue off of the unit and set aside

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7.  Remove the drain hose from Stainless Steel Heat Exchanger(SS HE)

(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)

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8.  Remove the cover and route wires – water level electrode

(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)

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Procedure| Diagram
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9.  Remove the heat exchanger from the case

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

(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

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10.  Separate the SS HE from the CU HE

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

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11.  Replacing the SS HE

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

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12.  Replacing the CU HE

(1)  Remove 10 screws holding the burner to the CU HE

(2)  Separate the burner from the CU HE

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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

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16.  Reattach Burner, CU HE, and SS HE

(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

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17.  Replace the assembly back inside the case

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

(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)

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Procedure| Diagram
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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

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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.|  |  |  |
 |  |

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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)

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Procedure| Diagram
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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

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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”

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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

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25.  Replace the front cover

(1)   Secure the front cover with 4 screws

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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.
Noritz America Corporation

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

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