Medium
E783 on Navien LCB700

Your boiler has lost communication with its smart thermostat or remote control unit, preventing it from receiving instructions on when to turn on the heating or hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Abnormal operation: OpenTherm remote control

DIY fix possible

Switch off the power supply to the boiler at the fused spur or circuit breaker.Locate the thermostat or remote controller and check that the wiring connections are secure.Wait 5 minutes for the system to reset, then turn the power back on to see if communication is restored.

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