I have a 10 year old combi boiler, I have had no issues with hot water until I changed my kitchen tap. The water flow rate seems the same as before but the combi boiler does not switch on, unless I open another hot water tap in house, and if this tap is then closed while the kitchen tap remains open the boiler stays on and supplies hot water. ![Confused :confused: :confused:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)