Vaillant Combi Boiler

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Vaillant Turbomax boiler fault code F20

Hi Guys,

My newly bought and installed Vaillant Turbomax boiler is displaying a F20 error code. I tried my best to fix at home after reading the Vaillant boiler’s user manual but unluckily no positive outcome. If someone has faced this issue then please help me.



Hi Tom, the F20 error code on the Vaillant Turbomax signifies an issue with a boiler overheating. I would like to share that the boiler has the device named as NTC thermistors. The purpose of these devices is to monitor the temperature of the water out & into the boiler. If the water temperature is very high, the boiler will go into lockout state because of overheating. The basic reason behind it is a low pressure of boiler due to lack of the water in your boiler.

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