Rinnai REU-2018W Service Manual page 45

Examination
Nature of Fault
D. Can not adjust water 1. Check water temper-
temperature. ature thermistor.
2. Check changeover
solenoid valve (SV
3. Check modulating
valve.
D. Can not adjust water 4. Check water flow
temperature. servo.
E. Anti-frost heater 1. Check anti-frost
does not work. heater.
2. Check frost sensing
switch.
Infinity REU-2425W
Diagnostic Point
Point
Disconnect connector C
measure resistance between
white-white.
See page 29, for temp. at vari-
ous resistance.
i) * Disconnect sld connector I
) from PCB; measure resistance
3
between blue-black.
ii) Measure voltage between
blue-black wire of change over
(SV ) at connector I
3
i) * Disconnect modulating
valve festoon terminal; meas-
ure resistance solenoid termi-
nals.
ii) Measure the voltage
between the two harness ter-
minals (still disconnected)
iii) Check whether the second-
ary gas pressure alters when
remote control temperature
°
alters 37~75 C.
i) Measure resistance between
red-blue water flow servo con-
nector I .
1
ii) Measure voltage between
orange (+) - grey (-) water flow
servo connector I
iii) Measure voltage between
brown-grey water flow servo
connector I (don't turn water
1
ON).
iv) Measure voltage between
yellow-grey water flow servo
connector I (don't turn water
1
ON).
i) * Disconnect connector J
measure resistance between
blue-blue (water valve)
ii) * Disconnect connectors J
measure resistance between
blue-blue. (heat exchanger).
Disconnect connector f
measure the resistance
between blue-blue. Atmos-
pheric temperature less than
± °
3
4 C.
Values
Resistance values
2;
match table on
page 29?
Ω
1.3~1.9k .
DC80~100V
.
3
Ω
60 ~ 100
DC0.5~25V
Does secondary volt-
age change?
Ω
10 ~ 30
DC11~13V
.
1
DC4 ~ 6V
Is voltage < DC 0.5V Yes
Ω
;
3
950~1050
Ω
;
3
135~170
Ω
;
3
Is resistance < 1
- 42 -
Y/N Action
Yes Go to D - 2.
No Replace water tempera-
ture thermistor.
Yes Go to D - 2 - ii).
No Replace (SV ).
3
Yes Go to D - 3.
No Replace PCB.
Yes Go to D - 3 - ii).
No Replace modulating
valve
Yes Go to D - 3 - iii).
No Replace PCB.
Yes Go to D - 4.
No Replace modulating
valve.
Yes Go to D - 4 - ii).
No Replace water flow
servo with sensor.
Yes Go to D - 4 - iii).
No Replace PCB.
Yes Go to D - 4 - iv).
No Replace water flow
servo with sensor.
Normal
No Replace water flow
servo with sensor.
Yes Go to E - 1 - ii).
No Replace anti-frost
heater (assy).
Yes Go to E - 2.
No Replace anti-frost B
(assy).
Yes Check wiring.
No Replace frost sensing
switch.
Issue 2 - 5/07/04 ©Rinnai
Repair
o
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