Firstly you cannot work on an unvented cylinder even if you own it unless you are qualified. If you make a mistake you can potentially make a bomb.
An unvented cylinder such as a megaflo is ideal for a conventional thermostatic mixer shower. Only problem is you will need a 'balanced supply' for the cold water for your shower to work properly. This must be taken from just after the inlet combination valve and before the expansion valve core unit.
Balanced supply instructions are in the manual or you could have a look at the website HERE
An unvented cylinder such as a megaflo is ideal for a conventional thermostatic mixer shower. Only problem is you will need a 'balanced supply' for the cold water for your shower to work properly. This must be taken from just after the inlet combination valve and before the expansion valve core unit.
Balanced supply instructions are in the manual or you could have a look at the website HERE