Vaillant VRT 350F wireless thermostat showing Zero

10 Dec 2020
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United Kingdom

I've recently had this installed and it started showing a lower temperature earlier today. I checked the batteries and now it shows Zero.

It's currently in Automatic mode but the heating will not come on.

I assume the Thermostat is broken, but my immediate issue is how do I disconnect the VRT 350F remote controller so I can go to manually control the boiler so we don't freeze...
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It looks like there is no temperature set, have you tried setting a time and temp in the auto settings or failing that go to manual mode ?
That large 0.0 C should be showing the actual temperature of the room it is in - obviously the room is not at freezing point. The room temperature sensor is inside the unit in your photo.

As a first step, I would try - going into the menu and try a 'factory reset'. You might need the installer code, which by default is '0000'.
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Your right chris, it might be the system switched off , to the op have you pressed any buttons on the main menu ?
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I know sensors when they fail often show 0°C, we use to program our machines so if the heater showed zero it would switch off, it was a safety feature, which caught me out, as I thought if showing zero heater should be on. As to if the domestic thermostat manufacturers also include that in their software I don't know, since you could actually get zero it seems unlikely.

Any other temperature I would say manual reset etc, but zero likely need a new thermostat, that is the temperature shown when the sensor fails.

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