Baxi Combi 105e

Had a job today at work on this boiler. Fault was no Hot water. When I got there, the water was going from cold to warm then coldish and warm again.

I thought it had to be dhw heat exchanger so I replaced it, and also replaced both thermistors whilst I was there. The problem is still the same though. The temperarure on the boiler goes upto about 50 and thats its. All I can think of thats left to change is the pcb.

My question though is this, how do you go about testing the thermistors, and pcb for this kind of fault?

Thanks

Did you check burner pressure gas rate flow rate combustion etc.thermister values vary with temperature so best to phone makers & they will tell you approximate values @ given temperatures

Make sure the DHW knob is correctly positioned onto the pcb so you are turning it up to max.

The knob spindle could of broke off or some one else could have been messing with it.