Paloma PH2-20R OFN Engineering Handbook page 79

Turn Remote Control OFF; unplug unit
and then ON again. Check DC voltage
across red and black wires on Molex
connector "B":
8 – 16 DC VOLTS
SVC 820-Tankless Gas Trouble Shooting Manual
66 – Error Code Diagnostic Chart
Is the DC voltage
OK?
YES
While Water Bypass Valve is operating (water is
flowing), check DC voltage across red and black wires
at Water Bypass Valve wiring harness:
8 – 16 DC VOLTS
Is the DC voltage
OK?
YES
Attempt to operate unit again. If the unit
malfunctions due to an Error Code 66:
Replace Water Bypass Valve
Attempt to operate unit again.
If the unit malfunctions due to an Error
NO
Code 66:
Replace Control Board
Attempt to operate unit again.
If the unit malfunctions due to an Error
NO
Code 66:
Replace Control Board
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