Potterton heatmax combi - dodgy hot water output.

[pizzadude66]

I have the Potterton Heatmax Combi boiler, and the HW is very iffy.
Turn on a hot tap, and nothing happens
Turn on heating, and then turn on a hot tap, and it has a bit of hot then cold then warm then cold constantly like that with each bit of HW lasting less than 2 seconds each time.
The CH is working perfectly.
I have attached a zip fiile with a video in it showing what the boiler is doing.
I have a likely suspect in my head, but don't want to prejudice people's ideas, so does anyone know how to diagnose this properly.
Best wishes
Jim

 

[gas112]

Take front case off and have a look to bottom left hand side behind pump when you turn hot water tap on can you see a red light

 

[pizzadude66]

Hi,
There is a red light but it is flickering on and off rapidly. Video attached in zip file

 

[gas112]

Hi,
There is a red light but it is flickering on and off rapidly. Video attached in zip file

in that case the turbine/bobbin that its attached to needs replaced its not sending correct signal to pcb it should be a solid light

 

[pizzadude66]

Ok thanks for that, i am going away onto a job for 4 weeks, will let you know how this progresses when I get back.