Air gap under copper cylinders

[Johnyc86]

Hi all
Thanks for the secondary return in plastic pipe replies....Nice one
Just have another question i can't find an answer to
How does the bottom of a hot water copper cylinder rot if there's no circulation of air passing through it.
I know it rots but actually why it rots is my question???

 

[Ric2013]

Bottom of cylinder is cold. With little movement of air, condensation could form and not, later, be able to dry out. My mother's Primatic cylinder only lasted 40 years, probably for this reason.

Ift he floor is oak, the timber contains tannic acid.

 

[Johnyc86]

Bottom of cylinder is cold. With little movement of air, condensation could form and not, later, be able to dry out. My mother's Primatic cylinder only lasted 40 years, probably for this reason.

Ift he floor is oak, the timber contains tannic acid.

Thanks