Got called to a flat today , just been done up , tennants moved in last week , saying no hot water coming thru tap in kitchen only. bathroom fine, there is a worceser combi in the flat in the bathroom . Hight pressure coming out of hot & cold in bathroom and cold tap in kitchen , but water is dribbling out of hot tap in kitchen, isolator under tap is open fully, and there is nothing wrong with the tap. pipes are running under concerete floor, any ideas what it could be? never seen a blockage on a pipe supplied with mains pressure before. there is so little water coming out of tap in kitchen that it wont hit the combi on.any ideas much appreciated