Baxi 80e problem.

[sads3110]

I had issues with DHW last week so I replaced the split diaphragm yesterday in my lunch break. The boiler fired up lovely, ch & hw was fab.
When I returned home from work, the boiler would not fire up for central heating, so on turning on the hot tap the boiler fired up but the water maintained a lukewarm temperature despite the plate heat exchanger being hot. The pump appears to be running and i'm buggered if I can put my finger on the problem

 

[Agile]

I would say that its impossible for the DHW to not be hot if the plate is hot.

But perhaps the inlet is hot but the rest cold. This can happen if the diverter valve rear section is sticking!

The CH should still function as normal though.

Is the pump starting on a CH demand?

Tony

 

[sads3110]

no, it just does not fire up at all on CH mode

 

[Agile]

It could be that the system flow switch is not working.

Tony

 

[sads3110]

There has been a development, when turning on the hot tap with very little flow, the water becomes hot, however when putting it on normal flow the water goes back to being luke warm but the rads also start to get luke warm.
Then when I attempted to trick the system by keeping the microswitch down whist the boiler was fired up, and turning the hot tap off which heated the radiators brilliantly until they reached temperature and the stat kicked in.
So whilst I'm thinking the diverter needs replacing, the fact that the CH side is dead without tricking the diverter makes me think the PCB is also suspect. Any thoughts??

 

[Agile]

The diverter valve is sticking as I pointed out before.

The boiler seems to have no call for heat. You need to check that the clock/roomstat is producing a call for heat on the boiler terminal.

Tony

 

[sads3110]

cheers mate, really appreciate your advice, i'll hopefully get it sorted over the weekend.