Rheem RTG74 User Manual

SVC 810 Tankless Troubleshooting Manual
55
Error Code 31
Explanation: Water Inlet Thermistor has malfunctioned. At a minimum check the following if
you get Error Codes 31, 32, 33, & 34:
1. Check for scale build up on the inlet filter screen. This scale build up could also happen
inside the machine. Scale build up on all thermistors will cause them to be inaccurate.
2. IF maintenance mode shows 32 degrees as the temperature, then the thermistor is not
making connection. (Possibly unplugged, possibly broken wire).
3. IF maintenance mode shows 199 degrees the thermistor has a direct short.
See Thermistor Resistance Chart for precise readings.
Error Code 32
Explanation: Heat Exchanger Thermistor has malfunctioned. At a minimum check the following:
Yes
The water heater appears to be
normal. Attempt to operate again.
Yes
Is the resistance
to the water
inlet thermistor
OK?
Measure the resistance of connector R
between Black#3 and White#6 wires:
7k (79
0
F) - 19 k (38
0
F) ohms
Dis
p
la
y
maintenance information line
[
3
y]
Water Inlet Thermistor tem
p
erature.
No
Replace Water Inlet
Thermistor
Re
p
lace Printer Circuit Boar
d
Does the
maintenance
information
indicate the cold
water inlet temp?
Yes
The water heater appears to be
normal. Attempt to operate again.
Yes
Is the resistance
to the heat
exchanger
thermistor OK?
Measure the resistance of connector R
between Black#3 and Yellow#5 wires:
4k - 19 k ohms
Dis
p
la
y
maintenance info
r
mation line
[
4
y]
Heat Exchan
g
er Thermistor tem
p
erature.
No
Replace Heat
Exchanger Thermistor
Re
p
lace Printer Circuit Boar
d
Does the
maintenance
information
indicate the heat
exchanger temp?

Rheem RTG74 Specifications

General

Brand	Rheem
Model	RTG74
Category	Water Heater
Language	English