Hi all, newbie here. Less than a year ago I had a new Vaillant Ecotec boiler installed with a VFT350F controller. It connects via a VR65 control box to my existing honeywell gravity fed cylinder. It works well when programmed to come on, but I have never been able to get the 'cylinder boost' function to work when I want an extra hour of hot water, which I now realise is because there was no VR10 NTC installed.
I installed one of these today on the return pipe and wired it to NTC connector in the the VR65, initially leaving the cylinder thermostat in place set at 70C as a back-up. The VRT350 now shows the cylinder temperature and will let me activate cylinder boost mode but unfortunately it won't let me change the desired cylinder temperature (just flashes). This means when cylinder boost is activated it reads 'desired temp 5.0 C' (and therefore doesn't actually turn the boiler on as the temp is about 30). I have also tried moving the VR10 to the space where the old honeywell thermostat was (in a space in the foam) and also disconnecting the thermostat from the VR65 but this makes no difference. Any ideas would be gratefully received - it's driving me mad!
Thanks,
I installed one of these today on the return pipe and wired it to NTC connector in the the VR65, initially leaving the cylinder thermostat in place set at 70C as a back-up. The VRT350 now shows the cylinder temperature and will let me activate cylinder boost mode but unfortunately it won't let me change the desired cylinder temperature (just flashes). This means when cylinder boost is activated it reads 'desired temp 5.0 C' (and therefore doesn't actually turn the boiler on as the temp is about 30). I have also tried moving the VR10 to the space where the old honeywell thermostat was (in a space in the foam) and also disconnecting the thermostat from the VR65 but this makes no difference. Any ideas would be gratefully received - it's driving me mad!
Thanks,
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