I have a wicks own brand aquatronic two ultra power shower that doesnt heat the water. my girlfriends dad installed it,but he says he can only install things, if they go wrong or dont work he cant fix them. theres hot water coming through all the taps, but not shower. I live in a ground floor flat with one flat above.
It's an electric shower - cold water goes in and electricity heats it up - nothing to do with having hot water at the taps. In the UK it may be an illegal installation if your girlfriend's dad is not a qualified electrician.