Baxi 105e instant diverter valve

Subby · Dec 16, 2016

Hi gang. Is anyone familiar with these boilers?

I have attended a job where there is no HOT water.

The micro switch that is attached to the top part of the diverter valve is working, but the pin is not coming forward when a hot tap is opened.

I changed the diaphragm but the old one was fine and it made no difference.

Baxi Technical support are now closed. Any pointers as I have to go back in the morning thanks

ShaunCorbs · Dec 16, 2016

does the pin move freely in and out of the bush

Subby · Dec 16, 2016

Yes I can pull it out with grips but the spring pulls it back in when I let go

Leo21 · Dec 16, 2016

Does the pin move when you run the hot tap? If it does it's your switch. You can buy the little pressure differential valve on its own. Just make sure you buy the little fibre washers with it.

Subby · Dec 16, 2016

No the pin doesn't move, and the switch is working, I poked a thin screwdriver down the hole and the boiler fired.

Last Plumber · Dec 17, 2016

You're best to change the whole thing, it comes in two parts but you can buy it as one item.
I would do that with those and change the lot

jtsplumbing · Dec 17, 2016

These are quite old boilers now and things where out, sometimes the service kits are a waste of time due to other factors inside the unit, so change the complete valve, also consider that the pump may need replacement if running weak.

Subby · Dec 17, 2016

Update: changed pneumatic venturi (no change) took both 4mm copper pipes off the diverter to check if blocked (were not) then took the diverter off the plate heat exchanger manifold, and the pin had stuck down in the manifold! I freed it with grips and silicone grease. This was causing the problem.
In the process I got water on the DHW thermistor which I then had to change and I got water on the PCB and clock (which I had to dry out with the mrs' hairdryer)
After all this the boiler fired with hot water tap on, only to send heat down the flow and return pipes and not the hw pipe (probably blocked plate heat exchanger) . To remedy this I had to turn the flow and return isolators almost closed and told customer to think of buying a new boiler.