Our friend Alan Graham wrote up this great project for venting cat litter box fumes out of his house. It's called the "Cat Jet", which implies much more hilarity than the actual project affords. As any cat owner knows, no matter how many cats you have or what type of litter you use, the cat box smell is something that you never quite get used to. My wife and I keep our litter box in the garage with access via a pet door. This summer the high heat made walking into the garage to do the laundry or even reach the car an exercise in chemical warfare. Once we made the mistake of leaving the car window open. I recently saw a post on Apartment Therapy showing a homemade "Cat Jet" ventilation solution (http://www.apartmenttherapy.com/ny/at-email/tools-for-pet-living-the-cat-jet-and-the-roomba-email-from-9108-062199) using a bathroom fan to vent the noxious fumes of a litter box from the inside of the house to the outside. As a home automation geek I immediately was inspired to take it up a notch by combining similar hardware to a series of timers. Behold: Alan's Automated Cat Jet! Total Cost? $80. Consisting of one bathroom fan, one bathroom vent kit, one Smarthome Appliance module, and my home automation system, Alan's Automated Cat Jet shows once again that with technology, anything is possible. Now you don't actually need to have as advanced a home automation system as I do to put this together, so I've given you an alternative solution using a special timer. Before you build my solution, I recommend checking out Chris' Cat Jet system first. It will give you an idea of how to mount a bathroom fan to an enclosed litter box and vent it out a window. For my solution, I just vented the litter box out the side of the house, as you would vent a dryer. Sorry neighbors! Parts list and more howto info after the jump.Parts Required: 1 TimerLinc Insteon Plug-in Timer from Smarthome http://www.smarthome.com/2456s3t.html 1 Bathroom Vent 1 Bathroom Vent kit 1 Extension Cord ----------- Total Cost $80 Most hardware stores will carry your average bathroom fans. You don't want anything too expensive. I bought a Broan 4" duct fan for $16 at Lowe's and a vent kit for $12. The bathroom fan should already come wired with a standard plug, so you can easily plug it directly into an outlet. I'd double check it before you purchase. Basically you are going to somehow mount the bathroom fan to a covered litter box. Since there are dozens of designs out there I'll leave that for you to figure out. However, once you've accomplished the fan mount and the vent, what you want to do is plug the fan into an extension cord and then into the Insteon timer which plugs into the wall. The timer will allow you to set a number of intervals for the fan to vent throughout the day and even has some randomizing features. If you so desired, you could combine this timer with a Smarthome motion detector as well. How Mine Works I already have a home automation system running off of a Mac Mini. This system allows me a little more control over how the fan works. In front of the litter box sits a motion detector. When the detector "sees" the cat, it tells the computer to start a timer. After 5 minutes (hopefully enough time for the cat, unless he's reading), the fan kicks on and vents the box for 15 minutes. That's just about enough time to take care of any major business that occurred. However, cat pee has that ammonia smell, so it doesn't take long for that to build up and overpower anything else. Because it releases over time during the day, it isn't enough to just vent when the cat uses the box. I wanted to keep the box venting. My system turns the cat fan on every hour for 5-10 minutes. This keeps the scent from building up, and since I run it only a short time, it really shouldn't affect the neighbors. However, as a safety precaution I placed a dryer sheet over the outside of the vent to perfume it up a bit. I do think a charcoal filter might work best in the near future. Thanks again Chris for the inspiration, I hope my take on it helps you as well! You can follow Alan's continued development of his Cat Jet over on the Treehugger forums.