What's this "lighter" Christian?

A heat bank can hold from 180 to 250 litres. A 50-50 combination unit of
125/125 is 250 too. If you go for an 80 litre cold section then even
lighter.

The standard Pandoras go from 130 litres to 415 litres. They also store more
energy than a same size conventional tank. They also don't have 80 litres+
cold water to weigh down the joists.

A 250 litre Pandora will run 2 baths (possibly 3) simultaneously no problem.
A 125/125 combination will run only one.

I never even get close to running out on a 180L model, but I oversized it as
I expect to install a second bathroom at some point.

Christian.