My central heating is designed so that the hot water and central heating can be used independently of each other. My query is this. I am going away for three weeks next January which may coincide with a cold snap. If I turn the cold water stop cock off (as I usually do when I go away) can I still leave the central heating on timer so that it comes on twice a day at a low temperature? There is obviously already water in the radiators, so i don't think this will be a problem, unless you know otherwise Thank you.