I am not a plumber and have not used these tanks before.
However, a qualified plumber did fit this tank using a couple of screws through a dry wall.
It has now fallen off, pulling away some of the plaster with it!!!
I shouldn't be surprised as they fell off in both my neighbours' houses too!
I have refitted it to the wall properly fixing it to wood so it will never fall off again.
My question is; does it matter if it is mounted upright or transversely?
The plumber fitted it transversely (on a hook mount) however it seems to make more sense fitted upright.
I can not find any information about this via google, so apologies for troubling you with this.