Ruud flashing 76 code

SOURCE: We have enjoyed a Rheem Thermostat and a Paloma

Before calling service technician, open following links for Rheem troubleshooting resources, including generic error codes and contact information for Rheem and recent manuals:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://www.fixya.com/tags/rtg_74pvn

Error codes are start place for troubleshoot, and multiple error codes can indicate bad PC board.
Same error code on one machine can be different cause and solution than another machine.

Error 76 is usually communication problem with remote control.
Disconnect wires from machine, and clean terminals is a start point.
Wire between machine and remote might be bad, or remote control is bad, or PC board or wiring connections are bad.

The problem might be solved by having technician catch the machine up on yearly maintenance.

Manual for same-similar product shows maintenance and troubleshooting and a few error codes, but not 76:
For the most part, the manual recommends calling service technician instead of offering DIY details.
http://waterheatertimer.org/pdf/DirectVentManualRTG-74PVN-1.pdf

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