My baxi combi boiler fires up and then goes out. can you please tell me what the problem is.?

Question

My Baxi combi instant 105 HE will not stay alight with the heating and water. It fires up and then goes out, it will not stay on. I have replaced the flame sensing electrode

Answer 1

make sure the pressure is ok & recharge the system if in doubt.. otherwise leave it to a technician

Answer 2

Possibly the pump is not starting up. so as son as the heat exchanger is hot, the water can't circulate and the boiler shuts down.

Answer 3

The fault is most probably the PCB if you've already changed the flame sensor. The flame sensor relays the message to the PCB that it's safe to allow the main gas through, & the PCB does the rest.  I assume you've checked things like the burner pressure (if the pressure is too low, the flame sensor won't be satisfied) and that the flame is actually touching the sensor. There are other things that could cause this problem, like a fan/air pressure switch fault or temp sensor. Good luck!  

Answer 4

British Gas Services do a one off call out deal. You could waste more time and money on replacing the wrong bits. They do know the job and have access to a diagnostic database plus more spares than any other company.

Answer 5

check also the thermistors .also try a help site which features  specific  issues with boilers as a qualified installer may help out with advise.