I’m not an accountant so I would need to refer this to my colleague.
In general any nominal account between 1-2999 (assets and liabilities) will show as an asset if in debit and a liability if in credit. I’m not sure of any special rules that are applied to the depreciation codes?
If you don’t mind I will send you a PM to get some more info on your account.
EDIT:
My colleague referred me to the following posts:
http://community.quickfile.co.uk/t/is-accumulated-depreciation-a-liability/1681
http://community.quickfile.co.uk/t/presentation-of-depreciation-in-balance-sheet/767