Installed a Nest 3rd generation thermostat as part of a new heating system. (S plan) When first fired up there was a permanent live to the heating even if everything was turned off at the stat. Went through all possibilities and checked my wiring which was fine. Put cover back on receiver and was about to give up when it started working. Tested it a number of times, turning the heating on and off and it appeared fine. The hot water side was working fine from the beginning.
Next day the issue returned, again went through everything but couldn't find a fault so returned the whole unit to my suppliers who swapped it with a replacement. Installed the replacement connecting to the existing cables just as they were, now heating is fine but i have the same issue with the hot water! Permanent live on 6 regardless of what is turned off on the stat. Hot water is running constantly unless the cylinder stat is turned down.
Any ideas please? Could it be a second faulty receiver? Ive followed various help links including a full reset but nothing works.
