Cat Litter BoxFan

(See the edit below)

We have just "inherited" a cat.
As she will be an inside cat, at least for a while, I needed to add a fan to her litter box.
Here is my attempt.
I was made a little easier as our inside gas hot water heater has been replaced with an external solar unit, so there is a ready built hole in the ceiling, and a chimney through the roof, but that is not connected as yet.
Having just junked a large photo copier that had 24V fans, a lager one was selected and it runs very well