Rheem RTG74 User Manual

SVC 810 Tankless Troubleshooting Manual
33
Error Code 66 (RTG66 Only)
Explanation: Water By-Pass Control fault. At a minimum check the following:
1. Verify there is water flow thru the unit even if the unit does not fire.
2. Access maintenance information to determine flow rate.
3. Check all wiring connections to the water control and connector B on the Printed Circuit
Board.
Measure the voltage at connector B between the
Red#7 and Black#8 wires for: 8 to 16 VDC
Measure the voltage at connector B between the Red#7 and Black#8
wires for: 8 to 16 VDC
Is the voltage to
the water by-
pass control
OK?
Yes
No
Replace the Printed Circuit Board
Turn power off;
unplug unit and
then on again.
When motor
operates, is the
voltage to the
water control
OK?
No
Re
p
lace the Printed Circuit Board
Re
p
lace the Water Control Assembl
y

Rheem RTG74 Specifications

General

Brand	Rheem
Model	RTG74
Category	Water Heater
Language	English