I have just moved into a new flat and can't work out how to heat the water!?

ring up the landloard or estate agent who sold you the place! We've fiddled with our central heating the night we moved into our place and caused major flooding of hte kitchen as we didn't know how it worked and just left the tap on that 'bleeded' the system. I wouldn't mess with it especially if it's a new flat - ring them up straight away and get them back in to sort you out!