Combi boiler/lack of hot water

I recently on advise had my boiler upgraded to a combi which worked well for constant hot water. However if the shower is being used and water is turned on anywhere else in the house the water runs cold and some times stops completely.I got a new shower fitted in main bathroom and it is an ornament as the pressure is so bad I was told this was due to the large showerhead.I have been advised to change back to cylinder and then a pump could be fitted.At the moment our large family are using ensuite shower which does not make sense after spending so much money on a bathroom refit.Please has anybody got any advise to give me as to what to do.

Ahaa, the Combi boiler in a large house one of their favorite subjects on this form : [broken link removed]

Basically you don’t have much choice, but to go back to a cylinder. It would be cheaper than the other option of a bigger Combi and but your problem sounds like not having enough mains water pressure to drive the current one.

Tnks Toger for reply. I was hoping to hear better news than that but at least I know which direction I need to go now. Isnt it a pity my plumber didnt forsee this problem