Rheem RTG74 User Manual

SVC 810 Tankless Troubleshooting Manual
54
Error Code 24
Explanation: Malfunction of Operational Switch. At a minimum check the following:
1. Disconnect remote control and retry.
2. Verify unit is electrically grounded. Do not use a 2 prong electrical adapter on the power
cord.
3. Press MAX (SW2) button on PCB to reset.
4. Press MIN (SW1) button on PCB to reset.
5. Check for presence of return circulation pump in the system.
Any water flowing thru the unit prior to turning unit ON may
cause error code 24.
Caution: This is a diagnostic test. Do not operate the water
heater for any length of time by pushing the SW1 or SW2 Button
on PC Board. Do not open a hot water tap.
Error Code 29
Explanation: Heat Exchanger outlet temperature is too low. At a minimum check the following:
1. Clean air inlet filter.
2. Check for buildup on the heat exchanger fins.
3. Set thermostat to 120 degrees. Verify heat exchanger temperature with water at hot
outlet.
Unit appears to be OK. Reset unit and attempt to operate without pushing the Min/Max (SW1/SW2)
Buttons.
Does the unit
operate by
p
ushing either the
Min or Max
b
utton?
Yes
No
Re
p
lace the Printed Circuit Board
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 - 10 k ohms
Dis
p
la
y
maintenance information line
[
4
y]
Heat Exchan
g
er Thermistor tem
p
erature.
N
o
Replace Heat
Exchanger Thermistor
Re
p
lace Printer Circuit Boar
d
Does the
maintenance
information
indicate the heat
exchanger temp?
N
o

Rheem RTG74 Specifications

General

Brand	Rheem
Model	RTG74
Category	Water Heater
Language	English