Please help. I have a problem with my Baxi Combi 105 HE.
There seems to be an intermittent fault which leads to the hot water (and central heating – the symptons are the same) only coming through luke warm. When hot water is turned on, the burner lights but then cuts out after around 8 seconds then restarts a few seconds later. The temperature does not go up above around 40 degrees (sometimes 30, sometimes 50).
I called a heating engineer out and he first of all replaced a split diaphragm and then the DHW temperature sensor (though in hindsight this couldn’t be the cause sine the fault is on the CH system also). He then tried a new PCB though this did not fix it.
As I say the fault is intermittent so sometimes the hot water and CH are fine and temperature goes up to around 80 degrees as I would expect.
This intermittent fault started some months ago but only occasionally did not work – now it has around a 10% success rate – so I am keen to get this sorted!
Not sure if this is a burner problem (gas valve? Gas pressure? But then why would the fault be intermittent) or a control issue (leading to burner cutting out at too low temperature – but, to me, this now seems unlikely given that PCB replacement did not fix and HW sensor has been replaced).
Really appreciate any advice?