which would you choose - one tank or two on brand new instalation

[FCLAUSON]

Guidence please

If you where building a system from scratch (as we are in our new build) would you

a) use a two tank system - solar heats smaller tank from which h/w comes and then any excess solar into larger buffer tank for use by the UFH (the cold water which is to be turned into hot water also gets preheated via the large tank prior to going to the smaller tank for full heat)
or
b) use a stratified tank e.g. Akvterm

confused about the most energy efficent option

[guydewdney]

b. I tried a - ok with a wood burner instead - useless. Wish I went with thermal store.

[wookey]

b. In principle this should have lower heat loses, but the choice is a complicated area with various tradeoffs. You can design an inefficient setup either way without much difficulty.