Error Code 24; Error Code 29; Error Code 31 - Rheem RTG2-42 Troubleshooting Manual

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.
Does the unit
operate by
pushing either the
Min or Max
button?
Yes
Unit appears to be OK. Reset unit and attempt to operate without pushing the Min/Max (SW1/SW2)
Buttons.

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.
Display maintenance information line [4y] Heat Exchanger Thermistor temperature.
Does the
maintenance
information
indicate the heat
exchanger temp?
Yes
The water heater appears to be
normal. Attempt to operate again.
No
Replace the Printed Circuit Board
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.
Is the resistance
No
to the heat
exchanger
thermistor OK?
Yes
Replace Printer Circuit Board
54
SVC 810 Tankless Troubleshooting Manual
No
Measure the resistance of connector R
between Black#3 and Yellow#5 wires:
4k - 10 k ohms
Replace Heat
Exchanger Thermistor