Hot Water Shower Problem

Hi all,

I have a Worchester 24CDI Boiler, and a Aqualisa Thermostatic shower (Aquarian). I have had problems when using the shower, it doesnt seem to demand hot water from the boiler. To kick start the boiler I have to run the hot water tap, sometimes after I turn it off the hot water tap the hot water from the shower does start to come through
sometimes...

This can take upto 30 mins to get the shower to run hot, and sometimes the hot water tap doesnt run hot with the shower either.

Having the CH on doesnt seem to make any difference.

Mainly I need to know do I need to change the shower unit or fix something with my boiler?

Thank you in advance

Could be the wrong cartridge in the shower, or various problems with the boiler.
New problem?

Hi sorry for being thick, but what do you mean by a 'wrong cartridge in the shower'?

Thank you...

Is the diverter valve working check that the hot water demand light comes on, on the boiler.