i have a potterton 810e puma fitted it is 6-7 years old. it is under homecare aggrement with bg. recently we have had problems with the hot water being very hot..so hot you can't keep your hand under it. bg came out and looked at the problem and changed the dhw and ch sensors and said that was the probelm. since then the problem has still been there. the knob on the front to change the temp doesn't appear to work despite it stating in the manual that it is able to change this between 43-65 degrees. the problem is more noticable now due to us having a thermostatic shower fitted as it now makes the shower go hot and cold...i presume because the valve is shutting off because the water is to hot. the flame light remains on when used with any tap but comes on and off when being used with the shower...because of the valve i presume. i have been told the boiler is hunting? can any one help. flow and pressure appear fine.