Hi,
I unfortunately have a Baxi Combi 105e (not the direct version).
I replaced the diverter diaphragm about 12 months ago which sorted out my first problem with the hot water.
Recently however it has developed new symptoms:

When a HW tap is on, the boiler fires up no problems so it looks like the diaphragm is still ok, but with the CH OFF at the control/timer switch, the HW only gets luke warm and the CH radiators warm up.

If the CH is on at the timer/control switch, the water gets hot.

There are no fault lights lit.

Any suggestions??

Sounds like a diverter valve on a dirty system if you replaced it 12 months ago

Hi Mart,

It looks as though your water is diverting into the heating when the hot tap is turned on, which basically tells us that the diverter valve needs replacing. However, I should seek advice from a competent and Gas Safe Registered engineer.

Regards,
Alan T