strange behaviour with .zsh and su

[Louis-David Mitterrand <mito@xxxxxxxxxxx>]

I recently switched to defining a ZSHDOTDIR in /etc/zprofile to
unclutter my home directory. It works fine when I am logged as a normal
user but now when I 'su' to root from that account root's .zshrc isn't
sourced anymore even though I put root's .zshrc into its own ZDOTDIR...

When I 'su -l' the .zsh/.zshrc is sourced but I'd rather it worked with
plain 'su' so that I don't change directories. 

Am I doing something wrong?

config:

Linux, zsh_3.0.3

export ZSHDOTDIR=.zsh

TIA

-- 

     Louis-David Mitterrand
     http://www.aparima.com/F1/
     mito@xxxxxxxxxxx