replace shower on new unvented system

[amelia1]

Refitting bathroom in new (to us) house, new unvented ch system fitted and now need to replace shower.
Elderly Mira thermostatic shower leaky and not worth keeping in refitted bathroom.
Opinions on here seem to favour Mira showers but which one? The existing one has a concealed valve and we would like to keep the uncluttered look. Is there any advantage of exposed over concealed valves?
Is fitting on unvented systems a DIY job or strictly not? Partner has fitted our other showers but never on unvented system.

 

[leakydave]

Mira EV valves, such as Excel, Fino, Element, Silver, Discovery, very easy to fit. Pipes through wall at 153mm centres and go from there. Don't put pipes where your are going to mount the valves itself on the wall. BIV models harder to fit and maintenance more of a pain, but not impossible. Fit isolation valves.

Unvented hot water gives no additional problems, but you may need to use the flow restrictor on some models. Usually cold pipe on the right as you look at the shower, but flows can be reversed on most models.

 

[WDIK]

Is fitting on unvented systems a DIY job or strictly not? Partner has fitted our other showers but never on unvented system.

fraid not, unvented is governed by G3 building regulations, not a diy job.

 

[leakydave]

I took it that the unvented cylinder was already in place...

 

[amelia1]

Yes! Entirely new and complete unvented system (everything from condensing boiler etc etc to radiators & trv's) professionally fitted but while original shower still usable it looks tatty and leaks a bit. Bank balance even more leaky...............

As the present shower is still working I assumed that any necessary changes from old system to new would have already been accomodated by the fitters? They didn't say not to use it when they left.

Also as the existing aged shower is a Mira thermostatic with a BIV I rather hoped it would be possible to 'swap them over' once we decided which one to use?