Unvented Santon Premier 120 litres v Open Vented 155 litres

[minimouse]

I am keen to make a decision and not sure which is the best option to go for either ;

an unvented Santon Premier plus system (120 litres) or an open vented cube thermal store.. (bespoke 155 litres)

The flat is 2 bedroom in a communal block on the third floor, mains water pipe 15mm... Will need to supply four outlets;

1 Bathroom (bath/sink/kitchen/toilet). Occupancy; 2 or 3...

Space is limited. Current system is an immersion system. My measurements 800 high x 600 (wide) x 600 depth..

Santon Disadvantages;

1) Discharge pipe -have to go into waste as on third floor
2) Unable to go for larger capacity due to space
3) May require yearly maintenance....
4) replacement expensive...

Adv

1) Modern/Efficient
2) Hot water on demand


Thermal Store

Disadv

1) elements fur up
2) outed...

Appreciate your thoughts.....