problem with vaillant 242e boiler

[the_dandan]

the central heating works fine on my boiler but the hot water takes ages to come on, if at all. a plumber reckons it may be the hot water heat exchanger.
i was just wondering if this sounds like the most likely solution and a rough idea of cost, materials and labour (i.e a big job?)
just tryin to work out if its better to get fixed or replace altogether?

any help is greatly appreciated, thanks

 

[Agile]

Its most likely to be a failing diverter.

Tony

 

[the_dandan]

thanks

 

[DP]

Does the burner fire within seconds of HW demand? If yes, the diverter is OK but problem elsewhere. If no, boiler is not seeing HW demand so diverter needs looked at as Tony suggests.