Gas safety certificate is not a completion certificate
should have a gas installion and building compliance which is issued by CORGI on behalf of the installer
He is right the condensing water is acidic having the strength of lemon juice but within 18 months will eat through lead and copper with dire consequences
Usually the gas pipe is below the condensing pipe and if it is leaking
Death can occur
Could be wiring fault to test remove head and put water on and cylinder stat set to high does the valve port to water only turn stat off does the valve port to off Do the same with heating only testing room stat and clock to on then off Does the valve port to off if all ok the wirings ok? Most likel...
It is there for your personal comfort.
so set on lowest to give you a comfortable surroundings as this is the cheapest choice but as its in the hallway might not give comfort in living room or bedrooms so adjust to all areas
