Rheem RTG74 User Manual

SVC 810 Tankless Troubleshooting Manual
52
Error Code 15
Explanation: Boiling Safety Device. The heat exchanger is too hot. At a minimum check the
following:
1. Check for restrictions in airflow around unit and vent terminal.
2. Check for a foreign materials in exhaust venting.
3. Back flush the unit to remote any sediment of buildup in the heat exchanger.
See section on how to display maintenance information.
No
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
Display maintenance information line [4y] Heat Exchanger Thermistor temperature.
If 4Y displays 199°F – then physically check heat exchanger (Remote cannot display over
199°F.)
If actual temperature reaches 207°F for 15 seconds, Error code 15 displays. Unit will re-start
at 194°F.
If actual temperature reaches 210°F for 1 second, unit shuts down. Unit will re-start at 194°F.
If actual temperature reaches 230°F, Error code 15 displays. Unit will not automatically
restart.
No
Replace Heat Exchanger
Thermistor.
Replace Printer Circuit
Board.
Yes
Does the
maintenance
information
indicate the heat
exchanger temp?

Rheem RTG74 Specifications

General

Brand	Rheem
Model	RTG74
Category	Water Heater
Language	English