hi this is my first post ive joined to see if i can get some help my friend has an halstead ace high combi boiler and its started to leak so im a bit ok with diy so i isolated the mains and removed cover and found the leak wihich is coming out of a small clear plastic tube top left hand side connected to boiler casing i pulled it away and drained the water from it then i reconnected it to the brass fitting,after starting up boiler and running water and heating the tube started to fill up agin with water after about 10min it started to drip down side of boiler again can any members please help thanx