Rheem RUUD AdvantagePlus - Water Temperature and Control Health; Water Temperature Probe Resistance; Control Board Self-Diagnosis

AdvantagePlus Fault Tree Troubleshooting
1706.doc
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WATER TEMPERATURE; problem with the water temperature probe or the water temperature
Explanation: This is the thermistor that monitors
the water temperature inside the tank. The LED is
ON when the water temperature drops below the
set point on the LED panel. If the water temp LED
is ON, then the unit should be in main burner or
attempting to fire off.
At a minimum check the following:
1. Temperature probe wiring is unplugged
2. Probe open internally
3. Probe wiring shorted
4. Probe shorted internally
5. Thermostat set point is OK. See
resistance chart at end of this document
6. If the display reads “255”, then the temperature probe is damaged and needs replacement
CONTROL HEALTH; problem with the control self diagnosis
If the unit is operating, but not holding temperature, verify the flow rate of water is within the GPM
performance for the temperature rise. If flow is not the problem, look at the ECO/Temperature
probe. There may be a hole in the probe allowing water into the electronics, thus causing a false signal.
Is there any
Ohms
resistance thru
the thermistor?
Yes
No
Replace temperature probe
Measure the OHM resistance between the two black wires at CN3.
Nominal reading is approx 12k (thousand) ohms at room
temperature (70
0
F); less resistance is cooler water; more resistance
is hotter water. An ‘open’ reading means the thermistor is
damaged.
See resistance chart on last page of this document.
Is the main
circuit board
OK?
No
Replace board
Press red reset button and recycle power. If error occurs repeatedly,
replace main control board.