Litter Box Vent Fan - Eliminate Cat Litter Stink

Picture of Litter Box Vent Fan - Eliminate Cat Litter Stink
CAUTION: Following these simple instructions may lead you to forget that you own a litter box, and therefore neglect to clean it. Please proceed with care.

I despise the smell of litter boxes. Even when cleaned well, the smell of cat litter can be overwhelming. It's ok if you live in a large house where you can dedicate a utility room, garage, or basement to the litter box. In an apartment, it is often impossible to keep a litter box out of smells reach.

For that reason, I made this simple litter box exhaust, which draws a small amount of air out of a covered litter box, and blows it outside. The computer fan draws just enough air to keep odors from escaping the box. The hot/cold air loss to the exterior seemed to be pretty minimal, because there is no noticeable change in heating/cooling costs. It works so well that people would be surprised that there were cats in the apartment.

The computer fan is rated at 0.13A, so it could easily be run off batteries being charged from a small solar panel outside. This instructable shows how to do just that:

Cats are generally freaked out by noise and weird stuff in the litter box. The fan is so quite, and far enough away from the litter box, that the cats did not care in the least bit. They were actually a little curious as to the dryer hose sticking in the box.

I built this system years ago, but was prompted to put it up after seeing this:
The bathroom fan seems like overkill, especially considering the fact that they cannot leave it on all the time.

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Step 1: Materials

Picture of Materials
1. Computer Fan
2. Plastic dryer hose
3. Sheet of Lexan
4. 2 Plastic cups that fit about 3/4 of the way into the dryer hose
5. Outdoor electrical junction box (which computer fan fits inside of)
6. Screws
7. Glue
8. 12 Volt wall power adapter
Lehmeier9 months ago

That's the patent my dad filed

moshbox6 years ago
I've got three cats. To say litter/odour control has been an issue is an understatement. I've gone through all sorts of contraptions from automatic rake systems to macerating cat toilets. This is a clever idea, but may not be suited well to multi-cat households where several boxes are required. I solved my problem with a simple change in litter formulation. I found a wheat-based litter that claims the natural enzymes break down the stank, and it does a great job. It doesn't clump well and one of the three won't use an all-wheat box, so I've found a mix of 1 part clay litter to 2 parts wheat litter is the perfect medium between happy cats, easy cleanup, and odour control. The only time I smell anything is if they don't bury it, which usually means I've missed a cleaning so I take that as a feline post-it note to clean the box.
katerlyn moshbox9 months ago

Wood pellets were suggested by and in the country you can burn it afterwards!

TXTCLA556 years ago
what if you were to attach the hose to a dyrer, so when the fan is on the air from the litter would escape through the dryer hose and ergo outside. however you would have to create a device that would allow air to leave the dryer but not allow cat litter air to stink up your clothes that are just sitting in the dryer.....hmmmm...
Just put a sort of a check valve on the dryer end of the "T" and I t would work...

There is a youtube with a T in the dryer vent.

Lehmeier4 years ago
My dad has a patent on the similar thing he made years ago.  hasn't made any money on it yet though.
katerlyn Lehmeier9 months ago

Can you send us a link?

AllVetMed1 year ago

Thanks for sharing these valuable information.

We know litter box is an indoor feces and urine disposal box for cats. And it is really helpful for cleaning my house form the bad smell of my pets. It is really useful and wroth of money.

Thanks for your design it's really helpful.
I built one out of plywood and used a range hood with fan and light,
the cats had a light for night use and the fan runs constantly on low venting outside through a separate vent in the wall.
total cost under $50 including new wood and vent tube and used range hood.
mikimouse113 years ago
I had a friend that made something similar years ago. He used a regular dome-lidded litter box and popped the hole in the top. But everything else was the same as this and it worked great. The cat smell used to be terrible before he made it. After that, when I'd go to their house, I couldn't tell they had a cat.
But, the cautions here are appeared to be easy to forget to clean it. When I looked in the box to inspect his new contraption, it was pretty nasty in there.
rhardy-14 years ago
I did something similar but went a different route. Check it out here.
susyrip5 years ago
Hi, My friends who have 10 cats (they use to own a cattery) have actually made a product called "LItter Vent" that absolutely works. You would never know that they have 7 cat litter boxes in their house. I'm not just saying this to promote them. It really does work. The only time you'd ever notice any cat box odor is when one of the fans stop working. It's available online, if anyone is interested. They sell it as a kit. Hope this helps anyone who's feeling desperate and can't take the smell any more.
Thank you for this information, since putting together this instructable solution would require me to be more handy than I am. I found the website and plan on ordering one to try it out.
yoshhash5 years ago
On the whole need for running a fan 24/7: Nice instructable, but there must be a way to do this passively. First idea that pops to mind is integrating it with a solar chimney- I know, I know, why don't I post my own instructable on how to do that? Well, now that I have said it, I will.
see-saw6 years ago
If you want it to be more efficient, you could rig up a motion detector to strike up the fan or a switch on the tray door or at a push even a pressure pad under the tray
dammat see-saw5 years ago
Maybe a timer would be better.
engineerable (author)  see-saw6 years ago
Nice suggestion, and it would probably work if the litter box was well sealed, but the problem is that cat crap doesn't stop smelling until it's dried up and fossilized. So turning the fan on during and for a period of time after the cat has done its business only removes some of the smell... granted it's better then nothing. It will continue to permeate into the surroundings. So ideally, the fan should run all the time, but move just enough air to keep the smell from escaping into the room.
Exactly. I like this idea. I've been thinking about the same thing for awhile, but all the ideas didn't coalesce as efficiently as yours.
evldrac766 years ago
I was wondering where the "optimal" placement of the fan would be.... on the litter box or by the window.... to blow out the undesirable odors. Would there be a difference?
Justdoofus6 years ago
So won't the cat suffocate to death if it's "sealed" and air is being Sucked out of the cat box?
oh my gosh, didn't realize how old this post was! 0.o
amyers576 years ago
This sounds great. With 6 cats I need to give it a try. Question, where did you get that litter box? Did you make it? I use one of those big plastic clear tubs as one of litter boxes and this would work great with that since it has a removable lid, but I like the corner unit you have.
engineerable (author)  amyers576 years ago
The cat litter box came from PetSmart.
I've never quite understood that, is it the Pets Mart, or is it implying that the store it self is very pet smart? i think i found a conspiracy here
Didn't you ever see the commercial that has all the animals going to petsmart? Then at the end of the commercial they say petsmart is pet smart?
sensemilla6 years ago
Where did you find the large encloser? Is it available online? I can only find ones with large holes as doorways.
ax896 years ago
Great idea. Do you have sharp ends of the screws sticking out on the outside of the lexan? Is this window large enough that this is a security concern? For others considering this but have a longer distance hose, I suggest using the solid duct pipe, 4" or whatever, because it will have less friction to the air and therefore will be more effective.
engineerable (author)  ax896 years ago
Thanks! This was on the 3rd story, so I just left the screws sticking out, and safety was not a concern. However, the window is small enough that I wouldn't be concerned about security. The sliding window was screwed into place to keep it from opening any more.
mpmayer6 years ago
dude great idea!! mont the fan on the litter box and add a carbon and hepa filter you got a gadget that`ll make ron popiel jealous!!
webman38026 years ago
Add a small solar panel to the system and you won't need to worry about the power bill. How does this system affect your heating and cooling costs in winter and summer? It seems like a fan continuously blowing air from the house to outside would cause some heat/cool air loss.
Calorie6 years ago
Great idea. I lived in a very small apartment. When my cat pooped it was disgusting beyond all belief. It got to the point where I would shoot up out of bed if I heard her in the litter box. I would clean it immediately because there was no way to ignore that stench. I would like to point out that I meticulously clean the box several times a day. That is, I scoop out clumped litter and feces as soon as I hear my cat in the utility room. I'm always surprised that people allow their boxed to fill up. My cat actually comes and retrieves me if I somehow miss the noise of her in the box.
good job
coffekid6 years ago
Grate job!!!! ppprrrrrrrrrrrrrrrrrrrrrrr!!
martysdad6 years ago
Hi, I had our litter box set up with a computer fan, specifically the processor fan which runs much leaner than the larger power adapter fan. Going 24 hours a day, for well over 6 months, our electricity bill in the bay area was no more than $9 a month. And that's including all of our own power usage in a one bedroom apartment. Worked really well, but yes you do have to be careful to remember that it is still there and needs changing! Poor kitty.
Guy.Fawkes6 years ago
An AC-powered exhaust fan will draw around 30 watts (or more, depending on design). The computer fan pulls about 1.6 watts. You can run the computer fan for 2 1/2 weeks for the same amount of current used for the bathroom exhaust fan in just 1 day.
shooby6 years ago
How is it energy efficient to run a fan 24/7, no matter what the size?
engineerable (author)  shooby6 years ago
I meant to say, energy efficient in comparison to a bathroom vent fan, which the link at the bottom uses, in which case they only run the fan intermittently.