45
Water Heating
NO
Safety device triggered
Flow is adjusted
than setting
outlet water temp. less
(1μA or more)
abnormality
Flame rod circuit
Outlet thermistor
open or shorted
Inlet thermistor
YES
Fan speed
> 0.5 GPM
YES
NO
normal
Initial check
YES
Hot water demanded
( )
Igniter stops sparking
others:after 2 sec.
1st, 4th, 7th:after 5 sec.
detects > 1 μA
Flame rod
Igniter sparks
Priority lamp (yellow) lights
Connect power
On/O button turn ON
Inlet water high
*1
Abnormal combustion
Fan speed
61
14
16 32
open or shorted
31
Inlet thermistor
open or shorted
31
32
71
Fix problem
Fan motor stops
(Flame rod)
(Ignition failure)
11
12
61
72
Stop hot water demand
Turn power O
Priority lamp turns OFF
Disconnect power
Water ow sensor detects
(target 200 rpm)
(After 60 sec)
open or shorted
Burner On Lamp
Outlet thermistor
Error code stops ashing
90
YES
NO
14
Normal
NO
YES
10
99
Self-diagnosis
Normal combustion
(High-limit switch)
20
99
to more than 10 years
Using terms is equivalent
Main ow control valve
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
YES
The unit will continue to operature with
the code blinking.
Warning indication
Warning indication
(Fan abnormality)
1
4
5
9
11
12
14
15
16
17
8
1
6
5
016
10
5
6
8
temperature check
Igniter stops sparking
At max BTU, is
goes o
closes
Gas solenoid Valve 3
Gas solenoid valve 2
opens
Primary gas solenoid
valve opens
Gas proportioning valve
opens
Fan motor ON
Burner on lamp
lights
Gas solenoid valve
opens or closes
Primary gas solenoid
valve closes
Gas solenoid valve 1
closes
Gas proportioning valve
closes
Burner On lamp
goes o
closes
Gas solenoid valve 2
closes
Primary gas solenoid
valve closes
Gas solenoid valve 1
closes
(0.5 μA or less)
not detect a ame
Flame rod does
is too high
Outlet water temp.
Abnormal gas solenoid
valve drive circuit
18
High limit switch
is normal
YES
NO (3rd)
Bypass ow control valve
and main ow control valve
move to initial position setting
device normal
Current leakage safety
NO
YES
of use
YES
5 years or more
NO
Maximum output limited
90
NO
YES
90
possible
Self-diagnosis
Normal combustion
possible
Self-diagnosis
Normal combustion
possible
Overheat prevention
device (Thermal fuse) normal
(Less than 363°F)
control valve operating
Main ow
YES
normal
NO
65
YES
Bypass ow
control valve operating
normal
NO
66
Setting 145 ° F or higher
YES
NO
Bypass ow control
valve closes
open or shorted
Heat exchanger thermistor
7
33
abnormality
Circuit board
70
(5 times or less)
YES
Extinction
NO
Re-ignition
(8 times or less)
Gas solenoid valve 1
13
Gas solenoid valve 2
closes
closes
Gas proportioning valve
Gas solenoid valve 3
opens
activates
33
Heat exchanger
open or shorted
7
thermistor
*3 When the present fan speed is 500rpm more or less than target speed.
abnormality
*3
(as necessary) *2
2
3
Overheat prevention
device (Thermal fuse)
triggered (363°F or more)
2
3
Warning indication
Warning indication
Warning indication
NR98 (-SV,-OD,-DVC) / NC199 (-OD,-DVC) / N-0751M (-OD,-DV,-DVC)
*4
Heat exchanger thermistor
YES
normal
NO
Freeze Prevention Control
exchanger thermistor
YES
41°F or higher
NO
Air inlet thermistor
YES
normal
NO
Air inlet thermistor
Less than 37 ° F
YES
NO
Heaters turn on
Heat
YES
Has 20(or 50)
NO
*5
min passed
Heaters turn o
*5
YES
NO
Has 15(or 5)
min passed
41°F or higher
Air inlet thermistor
NO
YES
Anti-Frost Heater Operation Flow
YES
YES
Fan motor stop
YES
Fan motor on
NO
NO
Less than 45 ° F
YES
34°F or higher
Air inlet thermistor
Air inlet thermistor
YES
YES
Heat exchanger thermistor
exchanger thermistor
YES
NO
normal
Heat
NO
normal
NO
*6
Fan Motor Operation Flow (NR98-SV/N-0751M Only)
NO
Higher than 30 ° F
Air inlet thermistor
Has 50 min
passed
30
30
19
19
indication
Warning
Warning
indication
Primary gas solenoid
valve closes
closes
closes
closes
Burner On lamp
Gas proportioning valve
Gas solenoid valve 2
Gas solenoid valve 3
goes o
Gas solenoid valve 1
closes
Shutdown procedure
On/O button turn ON
YES
NO
Fan motor post purge
Main ow control
valve opens fully
Fan motor stops
since hot water xture
Has 6min. passed
closed
YES
NO
Heat
exchanger thermistor
< 104 °F
NO
Water ow sensor detects
< 0.4 GPM
valve closes
Bypass ow control
Total water ow (GPM)
Approx. 18
K >
+ water inlet temperature ( °F)
Set temperature
K
If the inlet temp is less than 122
°
F
136
°
F
Set temp +9 °F
Less than 127
°
F
127 °F or more
or if the following statements
about K are true , the inlet temprature
will be normal (YES).
*1
BTU
110,000
Over
57,000
BTU
ON
Over
35,000
BTU
18,000
BTU
Over
8,000
BTU
Over
Gas solenoid
valve 1
Gas solenoid
valve 2
Gas solenoid
valve 3
ONON
ON
ON
ON ON
ONON
When less than 60 minutes after combustion, it is 50 °F or higher.
Diers depending on set temperature.
When less than 60 minutes after combustion, it is less than 54 °F.
*2
*4
*5
*6
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