The Fan Does Not Operate When The Hot Water Fixture Is Opened - Noritz NR501-OD Service Manual

1-2. The fan does not operate when the hot water fixture is opened.
Check whether the Water Flow Sensor is normal.
Normal
Check the Display Window ( 1).
Open the hot water xture fully.
Co n rm 0.5 gal/min. or more by
using maintenanc e monitor #14.
When not using the maintenance
monitor:
CN 63
Betwe en Red 10 – Blue 12
DC 14 – 16V
or
CN 63
Be tween Y ellow 9 (+) – Blu e 12 (-)
over 17 .8 Hz
Check the voltage between Red 10 and Blue12.
Check the pulses between Yellow 9 and Blue12.
Check whether the Thermistor-Cold Water Detection is too high.
(Check the Inlet Water temperature.)
Normal
Abnormal
*1 and *2 to the right *1 << How to check >>
do not apply in this
case.
*2
A
1 Check the Display Window.
When 1 minute passes after the water flow
is detected, the outside edge of the three
digit display will rotate in a circular pattern.
Abnormal
Circuit Board
14
13
12 BL
11 W
10 R
14
9 Y
8
13
7
6 BK
12 BL
5 BK
4 W
11 W 3 W
2 BK
10 R 1 W
<CN63>
1 2 3
9 Y
<CN135>
8
7
<CN78>
6
BK
2
1
5 BK
1 BL 2
3 BL
4 W 4 R
5 W
6
3 W O
7
GY
8 BK <CN10>
2 BK
9
10 W
1 W
11 BL
12
6 BK 13 W
5 R 14
<CN63>
15 BL
4
3
2 W
1 W
<CN42>
Abnormal
Normal
Abnormal
.
1
The Unit will not run to prevent scalding hot water temperature.
[001] : Water inlet temperature is too high
If possible decrease water inlet temperature
[002] : "Predicted water outlet temperature*
[004] : Inlet and Outlet temperature are reversed
Check the pipes and re-install it correctly
If "Predicted water outlet temperature" is too high, the Unit will not run to prevent scalding hot
water temperature.
Set Temperature (°F)
Less than 1 25°F
125°F or more
26.1
>
K
Total Flow Rate (gal/min)
K : Predicted outlet water temperature
26.1 : Coe c ient for NRC711-DV and NRC 711-OD
33
12 W
11 Y
10 O
9 R
8
7
Main
6 BK
5 V
Circuit
4 G
3 O
Board
2 Y
1 W
<CN59>
1
2
3 4 3 2 1
4 BL
4 R
3 BL BR Y BL R
5 O
2 BL
6 Y <CN27>
1 R
7 W
<CN142>
Power
<CN104>
Circuit
3 R
Board
2 BL
1 G
<CN101>
<CN89B>
3
2
1
<CN75>
3 2 1
BL/W R/R G
<CN89A> <CN102>
Check for improper connection of wiring.
Replace the W ater Flow Sensor.
" is too high
2
K ( Predicted water temperature)
136°F
Set Temperature + 18°F
+ Thermistor - Cold Water Detection Temperature (°F)
Check whether a solar water heater is directly coupled or
whether the hot w
Display Window
Fuse
Circuit Board
Data
Display
W 3 1 W
BK 4 2 BK
<CN92>
Dip Switch
1 2 3 4
R BL BL BL
<CN142>
Replace the Circuit Board
* It is not necessary to replace the
Display Window Circuit Board.
Replace the Circuit Board
* It is not necessary to replace the
Display Window Circuit Board.