Central Heating OK but temperamental Hot water

Hello, I have a Vaillant Turbo Max VUW242/1E; 240 KW; 80,000BTUs

The central heating works ok but hot water is only available when central heating is ON. Even then, after 5-6 open-and-shut of hot water tap, there is no hot water. I have to reset boiler, only then hot water is available, again only for 5-6 open/shut of hot water tap.

Is this a problem with the valve? Which valve? Is this something that I requires a qualified Plumber?
Also how much will a plumber normally charge for this. I am happy to get a good plumber in who knows his stuff. And does he have to be Corgi regd?

Or could this be an issue with the timer? I have obtained a Honeywell timer STC600 but not sure if this will go with Vaillant boiler

Pls advice
regards
Amod

HI

it sounds like the diverter valve is faulty

Most likely to be hw diaphragm.

On lower rhs behind pump you should be able to see a small switch on side of diverter valve.
When hot tap opened, can you see a white paddle move down to this switch?

, can you see a white paddle move down to this switch?

Click to expand...

not if its snapped

kevplumb said:

, can you see a white paddle move down to this switch?

Click to expand...

not if its snapped

Click to expand...

And the likely hood of this over the diaphragm being perished?

If the OP gets a service kit for this diverter valve then both scenario's are covered

true ive come across approx equal amounts of both when they first came out and always changed both as well as the plastic water section