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What is the Vaillant boiler F.20 fault / error code?

2 Answers

Answered by BoilerOne

25th May 2019

BoilerOne answered the question "What is the Vaillant boiler F.20 fault / error code?"

A vaillant boiler with an error code F.20 relates to an over heat to the thermistor on the heating flow or return, we would test the thermistor itself and test the cables from the pcb also looking for any damaged cables or loose connections. BoilerOne recommend you consult a gas safe registered engineer to diagnose the problem.

Answered by Landlord & Homeowner Gas Services

9th February 2019

Landlord & Homeowner Gas Services answered the question "What is the Vaillant boiler F.20 fault / error code?"

Hi I’m Greg from Landlord & Homeowner Gas Services. The F.20 fault code on a Vaillant boiler is likely due to a fault on the temperature limiter safety switch off. The likely causes are the following: - Incorrect earth connection between cable harness and boiler - Flow or return NTC defective Please ensure all work is carried out by a gas safe registered engineer. Thanks Greg Landlord & Homeowner Gas Services

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