I'm changing an existing electric shower for a thermostatic one running of an unvented cylinder.
I'm going to have the plumber (who's fitting the cylinder) run new hot and cold feeds through the wall into the shower, but do I need him to fit the controller also or is it pretty simple from that point on?
Make sure the pipe spacings are correct. Usually 150 I think but it does vary. Fwiw if I'd got a plumber to do that I'd get him to do the shower then it all his responsibility if there's any "issues"
It's going to add very little to the bill to get him to fit the controls while he is there.
Most of the work is in getting the pipe work to the right place and spaced correctly/ cut to the right length (and cut properly)
Fitting the controls won't take home long, as he knows exactly what he is doing.
We fitted/plumbed in our own shower and it was a real pain in the bum.
I'd pay someone to do it next time.