We have a 4 year old vaillant boiler ecoTec plus 630 and a water tank upstairs. Beside the boiler are 2 silver honeywell boxes. I presume these are called motorised valves. We also have a Honeywell ST9400C Programmer to control HW and CH separately.
Our plumber came to service the boiler yesterday and asked why one of the silver boxes has been set to ‘open’ rather than ‘auto’. To our knowledge we have not changed any settings on this box ever! We agreed that he should set it back to auto.
When CH came on later the towel rails in the bathrooms were cold (usually hot). The HW was not on at this point. I spoke to our plumber. He suggested overriding HW and waiting 20 mins. I did override and towel rails did not come on.
We agreed that I would set the silver box back to ‘open’ if it didn’t work. Once this had been done the towel rails came on.
Please could you let me know if there is any harm in having the silver box set to ‘open’? My plumber said that they should not be in ‘open’ as it is not how they are designed to work, but without in this position the towel rails do not work.
Our plumber is not now available for a week. The same guy installed the boiler and has serviced it each year but has never mentioned the silver boxes before.
We need warm bathrooms - please advise what I should do!