Project advice - cat litter box with HRV exhaust fan and motion trigger

Projects General Guidance
1

I've seen other projects like this, but I'm totally 100% new to Arduino and still reading through everything, so please be patient with me. Please tell me if this would be a decent Arduino project to try, and maybe how I could program it.

I want to accomplish one of the following scenarios, with a built in cat litter box in a new house I'm building. The box will be inside of a base built-in cabinet, accessible by a door for cleaning, etc. I want to run an exhaust line from my HRV system to pull the cat box smell out of the area.

Scenario 1:
A. Cat enters box and triggers motion sensor (IR beam?)
B. Motion sensor does the following:

  1. Triggers light inside box for a set time to stay on (say 5 min.)
  2. Starts a timer delay for the HRV exhaust to turn on (say also 5 min.)
    C. Upon leaving the box, second beam break does nothing. First does it all in step B.

--OR--

Scenario 2:
A. Cat enters box and triggers motion sensor
B. Motion sensor turns the light on.
C. Upon leaving, second beam break:

  1. Turns the light off
  2. Triggers HRV exhaust fan

I'm not sure, but I think the exhaust fan switches are wired with 18/3 thermostat wire at 12V. I'd have to check on the voltage.

Is this doable? Thank you in advance for your time. Again, I'm totally new to this, but excited at the possibilities!

2

You might want to consider a methane sensor. Just turn the fan on when it's stinky; no matter if the cat is present or not.