I just stopped getting hot water overnight, there was no problem with the central heating and also there were no fault LEDs showing.

When you turn the tap on a little plunger should come out of the diaphragm and push the micro switch to make the hot water LED come on and start heating the hot water. This stopped working, the fault was the circular rubber diaphragm, about 3inch diameter and ~£10, was perished.

It is really easy to change, just remove the small pipe going into the top of the diaphragm and then the 8 screws at the front. Make sure you fit the rubber thing in the correct way and reassemble everything in reverse order to dismantling it.

Hope this helps!


For reference the other problems I have had:

The 80degC LED was flashing, this turned out to be the central heating temperature sensor, ~£14 and you do not need to drain the system.

The 70degC LED was flashing, this turned out to be the hot water temperature sensor, ~£14 and just turn off the mains water tap.

Everything stopped, this was the main PCB, it was easy to change and cost £96.

All parts and drawings at www.partsarena.co.uk/baxi