Vaillant 828E not heating water

[WeymouthGuy]

Hi Guys/Ladies,

First off, i'm not a plumber, just here for some advice please.

I have a 5 year old Vaillant 828E wall mounted combi boiler.

When its heating water it shows a yellow light.
when hot water is being used, it also shows a flashing green light.

over the last 2-3 months it has become slower and slower to heat tap water,
but it doesnt happen all the time, sometimes hot water is almost instant, and other times it can run for 20 mins before the yellow boiler light comes on.

Today, its now failing to heat water at all, the green light flashes when the hot tap is running and you can hear a click from the boiler soon after turning the tap on, but the yellow light is now permanently off.

any idea what may be wrong, how i'd fix it and if its gonna cost me a lot?

thanks a lot.

 

[wnjswozo]

get a gas safe reg engineer out ,you wont be able to fix if not got any plumbing skills,and could end up doing more damage than good

 

[WeymouthGuy]

Thanks, I wasn't planning to tackle it myself, just wanted some clues what it may be before my plumber baffled me with science, so that I'm not ripped off. I've read up and think its either the air pressure switch or the diverter valve. Does that sound likely?

 

[wnjswozo]

divertor valve most likely

 

[weeman]

i agree probably diverter sticking