Noritz NR501-OD User manual

1
NORITZ America Corporation
Gas Water Heater
NR501-OD
NR662-OD
NRC661 (-DV, -OD)
NRC711 (-DV,-OD)
Service Manual
•Refer to this manual whenever performing service or
maintenance on this appliance.
•This manual will be used for service technician training seminars.
•The specifications and descriptions in this manual may be
changed without prior notice.
•For further assistance, contact Noritz Technical Support at
1-866-766-7489.
Do not short circuit any safety device on
this appliance
Rev: Dec, 2013
Contents
Important Safety Information .................................................................................................... 2
1. Specifications/Performance Table....................................................................................... 3
2. Dimensions ......................................................................................................................... 9
3. Components ....................................................................................................................... 12
4. Operating Principle ............................................................................................................. 16
5. Operation Flow Chart.......................................................................................................... 19
6. Wiring Diagram ................................................................................................................... 25
7. Troubleshooting .................................................................................................................. 28
•Error Codes and Checkpoints ......................................................................................... 28
•Circuit board checkpoints................................................................................................ 29
• Error Code Diagnostic Flow Charts .............................................................................. 31
•Displaying Maintenance Monitors ................................................................................... 59
•Maintenance Monitor List ................................................................................................ 60
•Circuit Board Replacement ............................................................................................. 61
•When Changing the Fan Motor ....................................................................................... 63
•Gas Line Requirements................................................................................................... 64
• Manifold Gas Pressure Adjustment................................................................................. 67
• Water Treatment ............................................................................................................. 73
• Periodic lnspection ......................................................................................................... 68
• Periodic Maintenance ..................................................................................................... 69
•Changing Default Temperature Setting ........................................................................... 75
8. Installation Check .............................................................................................................. 79
KS-11-0004
•Preventing Freeze Damage .................................................................................................. 76

2
Important Safety Information
To prevent damage to property and injury to the user, the icons below warn of
varying levels of risk.
Caution
Warning Ignoring this indication will cause an immediate danger of death or
serious injury.
Ignoring this indication may result in death or serious injury.
Prohibited.
1. Safety Tips for Service
•Wear the appropriate clothing and protective gear:
In order to prevent injury or accident, wear a protective helmet, safety boots and a
lifting belt whenever necessary.
Caution
•Use only the appropriate tools and parts:
Warning Only use replacement parts manufactured by Noritz for this model as listed in the
Installation Manual Parts List for service on this unit. Use appropriate tools.
•Modification of the unit is prohibited:
Do not attempt to modify or alter the unit. This will cause a re hazard and a risk of
electrical shock.
•When servicing:
Warning Disconnect the power supply during maintenance and repairs to reduce the risk
of electric shock. If it is necessary to have the electricity connected during repairs,
use extreme caution not to touch parts that may cause a shock.
•Do not short circuit any safety device on this appliance:
If a safety device is not functioning properly, replace the part. Do not under any cir-
cumstances short circuit the part.
•Exhaust and gas leakage caution:
Warning Always check for leaks when installing or modifying the exhaust vent or gas piping.
2. Post-Service Checks
•Check parts for leaks:
Caution Confirm that there are no gas, water, or exhaust leaks regardless of whether the
service performed could have caused them.
If the unit is installed indoors, check that the flue collar and vent pipe are installed
correctly and that they are in good condition. Confirm that there are no gas, water
or exhaust leaks regardless of whether the service performed could have caused
them.
•Check for combustibles:
Caution After service or maintenance is completed, check that there are no combustibles in
the vicinity of the unit.
•Check insulation resistance:
Warning After service or maintenance is completed, measure the resistance between the
electrical wires and ground. If it is less than 10MΩ, there is a risk of electrical
shock.
•Properly reconnect the power supply:
Warning Confirm that the power supply has been reconnected properly after service or
maintenance is completed. Also confirm that there is no dust or other obstacles
that might cause an electric shock or a fire hazard.

1. Specifications/Performance Table
Specifications
Specification
NR501-OD
Outdoor Wall Mounted
Direct Ignition
15-150 psi
0.5 GPM (2 L/min.)
32 lbs.
0.15 Gallon (0.5L)
3/4"
3/4”
1/2”
120 VAC (60Hz)
Zincified Steel Plate/Polyester Coating
Stainless Steel
Copper Sheeting, Copper Tubing
Stainless Steel Sheeting, Stainless Steel Tubing
Flame Rod, Thermal Fuse, Lightning Protection
Device (ZNR), Overheat Prevention Device, Freezing
Prevention Device, Fan Rotation Detector
Remote Controller, Remote Controller Cord,
Cross Recessed head screw
Item
Model Name
Type
Ignition
Operating Pressure
Minimum Flow Rate
Dimensions (Height) x (Width) x (Depth)
Weight
Water Holding Capacity
Accessories
Installation
Air Supply/Exhaust
Connection Sizes
Power Supply
Materials
Water Inlet
Hot Water Outlet
Gas Inlet
Condensate Drain
Safety Devices
Casing
Flue Collar
Primary Heat Exchanger
Secondary Heat Exchanger
Supply
Consumption
Power Vented
NG : 35W LP : 38W
Freeze Prevention 139W
20.5" (520mm) x 13.8"
(350mm) x 6.7" (170mm)
N/A
N/A
NR501-OD
NR662-OD
3
Specification
NR662-OD
Outdoor Wall Mounted
Direct Ignition
15-150 psi
0.5 GPM (2 L/min.)
35 lbs.
0.15 Gallon (0.5L)
3/4"
3/4”
3/4”
120 VAC (60Hz)
Zincified Steel Plate/Polyester Coating
Stainless Steel
Copper Sheeting, Copper Tubing
Stainless Steel Sheeting, Stainless Steel Tubing
Flame Rod, Thermal Fuse, Lightning Protection
Device (ZNR), Overheat Prevention Device, Freezing
Prevention Device, Fan Rotation Detector
Remote Controller, Remote Controller Cord,
Cross Recessed head screw
Item
Model Name
Type
Ignition
Operating Pressure
Minimum Flow Rate
Dimensions (Height) x (Width) x (Depth)
Weight
Water Holding Capacity
Accessories
Installation
Air Supply/Exhaust
Connection Sizes
Power Supply
Materials
Water Inlet
Hot Water Outlet
Gas Inlet
Condensate Drain
Safety Devices
Casing
Flue Collar
Primary Heat Exchanger
Secondary Heat Exchanger
Supply
Consumption
Power Vented
NG : 38W LP : 39W
Freeze Prevention 139W
20.5" (520mm) x 13.8"
(350mm) x 6.7" (170mm)

Specification
NRC661-DV NRC661-OD
Indoor Wall Mounted Outdoor Wall Mounted
Direct Ignition
15-150 psi
0.5 GPM (2 L/min.)
38 lbs. 36 lbs.
0.2 Gallon (0.8L)
3/4"
3/4”
1/2”
1/2” Threaded
120 VAC (60Hz)
NG : 54W LP : 56W
Freeze Prevention 138W
Zincified Steel Plate/Polyester Coating
PVC Stainless Steel
Copper Sheeting, Copper Tubing
Stainless Steel Sheeting, Stainless Steel Tubing
Flame Rod, Thermal Fuse, Lightning Protection
Device (ZNR), Overheat Prevention Device, Freezing
Prevention Device, Fan Rotation Detector
Remote Controller, Remote Controller Cord,
Anchoring Screws, SV Conversion Kit, Neutralizer
Item
Model Name
Type
Ignition
Operating Pressure
Minimum Flow Rate
Dimensions (Height) x (Width) x (Depth)
Weight
Water Holding Capacity
Accessories
Installation
Air Supply/Exhaust
Connection Sizes
Power Supply
Materials
Water Inlet
Hot Water Outlet
Gas Inlet
Condensate Drain
Safety Devices
Casing
Flue Collar
Primary Heat Exchanger
Secondary Heat Exchanger
Supply
Consumption
Power Vented
NG : 43W LP : 42W
Freeze Prevention 139W
23.6" (600mm) x 13.8"
(350mm) x 6.7" (170mm)
20.5" (520mm) x 13.8"
(350mm) x 6.7" (170mm)
NRC661(-DV/-OD)
Specification
NRC711-DV NRC711-OD
Indoor Wall Mounted Outdoor Wall Mounted
Direct Ignition
15-150 psi
0.5 GPM (2 L/min.)
41 lbs. 40 lbs.
0.2 Gallon (0.8L)
3/4"
3/4”
3/4”
1/2” Threaded
120 VAC (60Hz)
NG : 71W LP : 72W
Freeze Prevention 138W
Zincified Steel Plate/Polyester Coating
PVC Stainless Steel
Copper Sheeting, Copper Tubing
Stainless Steel Sheeting, Stainless Steel Tubing
Flame Rod, Thermal Fuse, Lightning Protection
Device (ZNR), Overheat Prevention Device, Freezing
Prevention Device, Fan Rotation Detector
Remote Controller, Remote Controller Cord,
Anchoring Screws, SV Conversion Kit, Neutralizer
Item
Model Name
Type
Ignition
Operating Pressure
Minimum Flow Rate
Dimensions (Height) x (Width) x (Depth)
Weight
Water Holding Capacity
Accessories
Installation
Air Supply/Exhaust
Connection Sizes
Power Supply
Materials
Water Inlet
Hot Water Outlet
Gas Inlet
Condensate Drain
Safety Devices
Casing
Flue Collar
Primary Heat Exchanger
Secondary Heat Exchanger
Supply
Consumption
Power Vented
NG : 52W LP : 53W
Freeze Prevention 139W
23.6" (600mm) x 13.8"
(350mm) x 6.7" (170mm)
20.5" (520mm) x 13.8"
(350mm) x 6.7" (170mm)
NRC711(-DV/-OD)
4

Item
Gas
Consumption
Maximum Hot Water Capacity
Capacity Range
Temperature Settings
Default Temperature Options
NG
LP
45°F (25°C) Rise
Maximum Performance
120,000 btuh
120,000 btuh
Minimum Performance
15,000 btuh
15,000 btuh
4.2 GPM (16.0 L/min.)
0.5-5.0 GPM (2-19.0 L/min.)
115-140 °F (6 Options)
°F Mode:
°C Mode: 46-48°C (In 1°C intervals),
50,55,60°C (In 5°C intervals) (6 Options)
120°F (50°C), 130°F (54°C), 135°F (57°C),
140°F (60°C) (Original is 120°F (50°C))
Performance
Item
Gas
Consumption
Maximum Hot Water Capacity
Capacity Range
Temperature Settings
Default Temperature Options
NG
LP
45°F (25°C) Rise
Maximum Performance
140,000 btuh
140,000 btuh
Minimum Performance
15,000 btuh
15,000 btuh
4.2 GPM (16.0 L/min.)
0.5-6.6 GPM (2-25.0 L/min.)
115-140°F (In 5°F intervals) (6 Options)
°F Mode:
°C Mode: 46-48°C (In 1°C intervals),
50,55,60°C (In 5°C intervals) (6 Options)
120°F (50°C), 130°F (54°C), 135°F (57°C)
140°F (60°C) (Original is 120°F (50°C))
Item
Gas
Consumption
Maximum Hot Water Capacity
Capacity Range
Temperature Settings
Default Temperature Options
NG
LP
45°F (25°C) Rise
Maximum Performance
157,000 btuh
157,000 btuh
Minimum Performance
15,000 btuh
15,000 btuh
6.3 GPM (24.0 L/min.)
0.5-7.1 GPM (2-27.0 L/min.)
115-140°F (In 5°F intervals) (6 Options)
°F Mode:
°C Mode: 46-48°C (In 1°C intervals),
50,55,60°C (In 5°C intervals) (6 Options)
Item
Gas
Consumption
Maximum Hot Water Capacity
Capacity Range
Temperature Settings
Default Temperature Options
NG
LP
45°F (25°C) Rise
Maximum Performance
120,000 btuh
120,000 btuh
Minimum Performance
15,000 btuh
15,000 btuh
4.9 GPM (18.4 L/min.)
0.5-6.6 GPM (2-24.8 L/min.)
100-140°F (In 5°F intervals) (9 Options)
°F Mode:
°C Mode: 37-48°C (In 1°C intervals),
50,55,60°C (In 5°C intervals) (15 Options)
120°F (50°C), 135°F (57°C), 140°F (60°C)
(Original is 120°F (50°C))
120°F (50°C), 135°F (57°C), 140°F (60°C)
(Original is 120°F (50°C))
NR501-OD
5
NR662-OD
NRC661 (-DV/-OD)
NRC711 (-DV/-OD)

Hot Water Supply Capability
[Spring / Fall]Inlet water temp. 64F
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [F]
[Summer] Inlet water temp. 82F
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [F]
80
90
100
110
120
130
140
150
160
0 1 2 3 4 5 6 7 8
Flow Rate [GPM]
Set Tempearture [F]
[Winter]Inlet water temp. 48F
[Winter] Inlet water temp. 46 ℉
Flow Rate [GPM]
Set temperature [ ℉]
80
90
100
110
120
130
140
150
160
012345678
[Spring / Fall] Inlet water temp. 64 ℉
Flow Rate [GPM]
Set temperature [ ℉]
80
90
100
110
120
130
140
150
160
012345678
[Summer] Inlet water temp. 82 ℉
Flow Rate [GPM]
Set temperature [ ℉]
80
90
100
110
120
130
140
150
160
012345678
<NR501-OD>
<NRC661-DV / NRC661-OD>
[Spring / Fall] Inlet water temp. 64 ℉
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
[Summer] Inlet water temp. 82 ℉
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
[Winter] Inlet water temp. 46 ℉
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
<NR662-OD>
<NRC711-DV / NRC711-OD>
[Winter] Inlet water temp. 46 ℉
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
[Summer] Inlet water temp. 82 ℉
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
80
90
100
110
120
130
140
150
160
012345678
Flow Rate [GPM]
Set temperature [ ℉]
[Spring / Fall] Inlet water temp. 64℉
6

Pressure Loss Characteristics
7
<NR501-OD>
<NR662-OD>
0
5
10
15
20
25
30
0.01.0 2.0 3.04.05.06.0 7.0 8.0
Flow rate [GPM]
Pressure loss [psi]
0
10
20
30
40
50
60
Pressure loss [Ft. of head]
0
5
10
15
20
25
30
0.01.0 2.0 3.04.05.06.0 7.0 8.0
Flow rate [GPM]
Pressure loss [psi]
0
10
20
30
40
50
60
Pressure loss [Ft. of head]

0
5
10
15
20
25
30
35
40
0.01.0 2.0 3.04.05.06.0 7.0 8.0
Flow rate [GPM]
Pressure loss [psi]
0
10
20
30
40
50
60
70
80
90
Pressure loss [Ft. of head]
0
5
10
15
20
25
30
35
40
45
50
0.01.02.03.04.05.06.0 7.0 8.0
Flowrate [GPM]
Pressure loss [psi]
0
10
20
30
40
50
60
70
80
90
100
110
Pressure loss [Ft. of head]
8
<NRC661-DV, NRC661-OD>
<NRC711-DV, NRC711-OD>

13.1" (334mm)
13.8" (350mm)
1.7" (42mm) 2.2" (57mm)
20.5" (520mm)
7.0" (178mm)
2.9" (73mm)
AIR INLET
DISPLAY WINDOW
13.3" (338mm)
COLD WATER INLET
HOT WATER OUTLET
WATER DRAIN VALVE
WIRING THROUGHWAY
GAS INLET
(AC120V)
WIRING THROUGHWAY
(WATER FILTER)
WATER DRAIN VALVE
6.7" (170mm)
0.4" (11mm)
0.4" (10mm)
0.4" (10mm) 5.2" (133mm)
1.1" (27mm)
1.6" (40mm)
AIR INLET
2.0" (50mm)
3.3" (85mm)
4.7" (120mm)
0.4" (10mm)
0.4" (10mm)
21.3" (542mm) 19.2" (487mm) 1.2" (31mm)
0.3"×0.6" (3-6.5 16.5mm) OBLONG HOLE
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
< inch (mm) >
4- φ0.5" (φ13mm)
2.4" (60mm)
3.5" (90mm)
4.7" (120mm)
4- φ0.5" (φ13mm)
1.6" (40mm) 3.2" (80mm)
1.8" (45mm) 3.8" (97mm) 1.6" (40mm)
1.4" (36mm)
5.5" (139mm)
8.2" (208mm)
9.9" (252mm)
11.7" (296mm)
WIRING THROUGHWAY
(AC120V)
WIRING THROUGHWAY
GAS INLET (1/2")
COLD WATER INLET (3/4")
(VIEW FROM TOP)
HOT WATER OUTLET (3/4")
HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
(NR501-OD)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 1.9" (49mm)
GAS INLET 2.0" (50mm)
2. Dimensions
<NR501-OD>
1.5" (37mm)
AIR INLET
DISPLAY WINDOW
COLD WATER INLET
HOT WATER OUTLET
WATER DRAIN VALVE
WIRING THROUGHWAY
GAS INLET
(AC120V)
WIRING THROUGHWAY
(WATER FILTER)
WATER DRAIN VALVE
AIR INLET
13.1" (334mm)
13.8" (350mm)
1.7" (42mm) 2.2" (57mm)
20.5" (520mm)
8.4" (214mm)
13.3" (338mm)
6.7" (170mm)
0.4" (11mm)
0.4" (10mm)
0.4" (10mm) 5.2" (133mm)
1.1" (27mm)
1.6" (40mm)
2.0" (50mm)
3.3" (85mm)
4.7" (120mm)
0.4" (10mm)
0.4" (10mm)
21.3" (542mm)
19.2" (487mm) 1.2" (31mm)
3-0.3"×0.6" (6.5 16.5mm) OBLONG HOLE
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
< mm (inch) >
4- φ0.5" (φ13mm)
2.4" (60mm)
3.5" (90mm)
4.7" (120mm)
4- φ0.5" (φ13mm)
HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
(NR662-OD)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 1.9" (49mm)
GAS INLET 2.0" (50mm)
1.6" (40mm) 3.2" (80mm)
1.8" (45mm) 3.8" (97mm) 1.6" (40mm)
1.4" (36mm)
5.5" (139mm)
8.2" (208mm)
9.9" (252mm)
11.7" (296mm)
WIRING THROUGHWAY
(AC120V)
WIRING THROUGHWAY
GAS INLET (3/4")
COLD WATER INLET (3/4")
(VIEW FROM TOP)
HOT WATER OUTLET (3/4")
<NR662-OD>
9

10
13.1" (334mm)
13.8" (350mm)
φ3.5" (φ89mm) φ3.5" (φ89mm)
5.9" (150mm) 4.9" (125mm)
23.6" (600mm)
AIR INLET FLUE COLLAR
DISPLAY WINDOW
COLD WATER INLET
WATER DRAIN VALVE
HOT WATER OUTLET
CONDENSATE DRAIN
WIRING THROUGHWAY
GAS INLET
(AC120V)
WATER DRAIN VALVE WATER DRAIN VALVE
(WATER FILTER)
0.4" (10mm)
0.4" (10mm)
6.7" (170mm)
1.1" (28mm)
22.3" (567mm)
0.8" (21mm)
3.5" (90mm)
1.2" (31mm)
13.3" (338mm)
2.4" (60mm)
4.7" (120mm)
24.5" (622mm)
0.4" (10mm)0.4" (10mm)
2.0" (50mm)
4.7" (120mm)
3.5" (90mm)
3.3" (85mm)
3-0.3"×0.6" (6.5×16.5mm) OBLONG HOLE
4-φ0.5" (φ13mm)
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
4-φ0.5" (φ13mm)
< inch (mm) >
HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
NRC661-DV
CONDENSATE DRAIN 0.8" (20mm)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 2.3" (58mm)
GAS INLET 2.0" (50mm)
0.8" (21mm)
1.8" (45mm) 3.4" (87mm)
3.8" (97mm)
1.2" (31mm)
3.8" (96mm)
4.1" (103mm)
10.0" (253mm)
1.6" (40mm)
11.7" (297mm)
(VIEW FROM TOP)
GAS INLET(1/2")
WIRING THROUGHWAY
COLD WATER INLET(3/4")
HOT WATER OUTLET(3/4")
CONDENSATE DRAIN(1/2")
0.4" (10mm)0.4" (10mm)
2.0" (50mm)
4.7" (120mm)
3.3" (85mm)
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
4-φ0.5" (φ13mm)
21.3" (542mm)
0.4" (10mm)
0.4" (10mm)
19.2" (487mm)
1.2" (31mm)
6.7" (170mm)
1.6" (40mm)
1.1" (27mm)
0.4" (11mm)
5.2" (133mm)
AIR INLET
2.4" (60mm)
4.7" (120mm)
3.5" (90mm)
3-0.3"×0.6" (6.5×16.5mm) OBLONG HOLE
4-φ0.5" (φ13mm)
WATER DRAIN VALVE
HOT WATER OUTLET
CONDENSATE DRAIN
WATER DRAIN VALVE
COLD WATER INLET
WIRING THROUGHWAY
GAS INLET
(AC120V)
WATER DRAIN VALVE
(WATER FILTER)
WIRING THROUGHWAY
DISPLAY WINDOW
AIR INLET
13.8" (350mm)
13.1" (334mm)
8.5" (217mm)
2.2" (56mm)1.1" (28mm)
20.5" (520mm)
1.1" (28mm)
13.3" (338mm) < inch (mm) > HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
NRC661-OD
CONDENSATE DRAIN 0.8" (20mm)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 2.3" (58mm)
GAS INLET 2.0" (50mm)
COLD WATER INLET(3/4")
HOT WATER OUTLET(3/4")
0.8" (21mm) 1.8" (45mm) 3.4" (87mm)
3.8" (97mm)
1.2" (31mm)
3.8" (96mm)
4.1" (103mm)
10.0" (253mm)
8.2" (209mm)
1.9" (47mm) 1.6" (40mm)
11.7" (297mm)
(VIEW FROM TOP)
GAS INLET(1/2")
WIRING THROUGHWAY
CONDENSATE DRAIN(1/2")
WIRING THROUGHWAY
(AC120V)
<NRC661-DV>
<NRC661-OD>

<NRC711-DV>
<NRC711-OD>
11
13.1" (334mm)
13.8" (350mm)
φ3.5" (φ89mm) φ3.5" (φ89mm)
5.9" (150mm) 4.9" (125mm)
23.6" (600mm)
AIR INLET FLUE COLLAR
DISPLAY WINDOW
COLD WATER INLET
WATER DRAIN VALVE
HOT WATER OUTLET
CONDENSATE DRAIN
WIRING THROUGHWAY
GAS INLET
(AC120V)
WATER DRAIN VALVE WATER DRAIN VALVE
(WATER FILTER)
0.4" (10mm)
0.4" (10mm)
6.7" (170mm)
1.1" (28mm)
22.3" (567mm)
0.8" (21mm)
3.5" (90mm)
1.2" (31mm)
13.3" (338mm)
2.4" (60mm)
4.7" (120mm)
24.5" (622mm)
0.4" (10mm)0.4" (10mm)
2.0" (50mm)
4.7" (120mm)
3.5" (90mm)
3.3" (85mm)
3-0.3"×0.6" (6.5×16.5mm) OBLONG HOLE
4-φ0.5" (φ13mm)
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
4-φ0.5" (φ13mm)
< inch (mm) >
HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
NRC711-DV
CONDENSATE DRAIN 0.8" (20mm)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 2.3" (58mm)
GAS INLET 2.0" (50mm)
0.8" (21mm) 1.8" (45mm) 3.4" (87mm)
3.8" (97mm)
1.2" (31mm)
3.8" (96mm)
4.1" (103mm)
10.0" (253mm)
1.6" (40mm)
11.7" (297mm)
(VIEW FROM TOP)
GAS INLET(3/4")
WIRING THROUGHWAY
COLD WATER INLET(3/4")
HOT WATER OUTLET(3/4")
CONDENSATE DRAIN(1/2")
0.4" (10mm)0.4" (10mm)
2.0" (50mm)
4.7" (120mm)
3.3" (85mm)
2-0.3"×0.5" (6.5×13mm) OBLONG HOLE
4-φ0.5" (φ13mm)
21.3" (542mm)
0.4" (10mm)
0.4" (10mm)
19.2" (487mm)
1.2" (31mm)
6.7" (170mm)
1.6" (40mm)
1.1" (27mm)
0.4" (11mm)
5.2" (133mm)
AIR INLET
2.4" (60mm)
4.7" (120mm)
3.5" (90mm)
3-0.3"×0.6" (6.5×16.5mm) OBLONG HOLE
4-φ0.5" (φ13mm)
WATER DRAIN VALVE
HOT WATER OUTLET
CONDENSATE DRAIN
WATER DRAIN VALVE
COLD WATER INLET
WIRING THROUGHWAY
GAS INLET
(AC120V)
WATER DRAIN VALVE
(WATER FILTER)
WIRING THROUGHWAY
DISPLAY WINDOW
AIR INLET
13.8" (350mm)
13.1" (334mm)
8.5" (217mm)
2.2" (56mm)1.1" (28mm)
20.5" (520mm)
1.1" (28mm)
13.3" (338mm) < inch (mm) >
HEIGHT OF EACH FITTING
FROM BOTTOM OF CASE
NRC711-OD
CONDENSATE DRAIN 0.8" (20mm)
HOT WATER OUTLET 1.8" (45mm)
COLD WATER INLET 2.3" (58mm)
GAS INLET 2.0" (50mm)
COLD WATER INLET(3/4")
HOT WATER OUTLET(3/4")
0.8" (21mm) 1.8" (45mm) 3.4" (87mm)
3.8" (97mm)
1.2" (31mm)
3.8" (96mm)
4.1" (103mm)
10.0" (253mm)
8.2" (209mm)
1.9" (47mm) 1.6" (40mm)
11.7" (297mm)
(VIEW FROM TOP)
GAS INLET(3/4")
WIRING THROUGHWAY
CONDENSATE DRAIN(1/2")
WIRING THROUGHWAY

12
<NR501-OD>
Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure Tap
Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure Tap
3. Components
<NR662-OD>

Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure Tap
Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure Tap
<NRC661-DV>
<NRC661-OD>
13

<NRC711-DV>
14
<NRC711-OD>
Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure TapManifold Pressure Tap
Thermistor-Cold Water
Thermistor-Hot Water
Manifold Pressure Tap

The display window allows you to view the status
of unit or error codes.
Display Window
When other indication will appear, please refer to troubleshooting(Owner's guide).
(Ex.NRC661-DV)
(Display Window)
When the gas burner is on.
When the gas burner is on, set
temperature is
displayed for one minute.
When hot water flows.
If there is a problem with the unit, a numerical
error code will flash.
When unit is initially plugged into power,
set temperature is displayed for approx. three minutes.
(When the gas burner is off, and cold water flows.)
After one minute elapses from initial call for hot water, the outside edge of
the three digit display will rotate in a circular pattern.
On
(Ex.: error code 11)
15

Thermistor-Cold Water
Thermistor-
Hot Water
Gas Proportioning Valve
4. Operating Principle
16
<NRC661 (-DV, -OD), NRC711 (-DV, -OD)>

<NR501-OD, NR662-OD>
Thermistor-Cold Water
Thermistor-
Hot Water
Gas Proportioning Valve
17

< How to Use >
1.Normal Operation
(Hot Water Production)
1. Turn the unit on.
- If an optional remote controller is not installed with the unit, the unit will be on as soon as
electricity is connected to it.
*When electrical power is connected to the unit, the Set Temperature is displayed for
approx. 3 minutes on the Display Window.
- If a remote controller is installed, the "POWER" button will need to be pushed to turn
the unit on.
2. Whenever a hot water fixture is opened, or an appliance that requires hot water is turned
on, as soon as the flow sensor detects at least the minimum flow rate required combustion,
the fan will iniate and pre-purge any residual combustibles in the combustion chamber.
The igniter will then create a spark and the gas valves will open allowing fuel into
the combustion chamber where it be ignited by the spark.
3. When the flame rod detects a flame, the igniter will stop sparking.
4. The computer will then control the gas and water control valves to maintain the water at
the temperature setting. The temperature can be adjusted by DIP switches on the Display
Window circuit board, or by changing the remote controller setting if one is installed.
5. When the demand for hot water ceases, the unit will stop heating.
When the flow sensor detects that the rate has dropped below the minimum rate for
continued burning, the gas valves will close and the burner flame will go out. After the post
purge removes residual gas from combustion chamber, the unit stops.
If necessary, turn off the power by either disconnecting the power supply, or pressing
the "POWER" button on the remote controller if one is installed.
2. Error Codes
If the flame rod does not detect a flame, or if the high limit switch has been triggered,
the gas valves will close, the flame will go out, and an error code will flash on
the Display Window or the Optional Remote Controller if one installed.
In order to reset the unit and remove the error code, turn the power off by either
disconnecting the power supply or by pressing the "POWER" on the Optional Remote
Controller, and then press it again to turn the unit back on.
If the problem requires service (the thermal fuse is triggered,etc) the gas valve will stay
closed and resetting the unit will not eliminate the error code. If this is the case, the unit
must be serviced before it will work again.
3. Miscellaneous
If the unit will not be used for a long period of time, turn off the power, drain the unit
of water, and close the manual gas valve on the supply line.
18

19
5. Operation Flow Chart
Water heating
Shutdown procedure
Ignition operation
<NR501-OD>

Water heating
Shutdown procedure
Ignition operation
20
<NR662-OD>