Purpose:

1. Some pets, like Chinchillas, need to be kept cool, and the summer in Japan (and many other places) is too hot.

2. Using an air conditioner to cool a whole room continuously uses a lot of electricity. Cooling only a cage would draw far less energy, save money, and be much more green.

3. Some houses have electrical grids which can only handle 15 amps, and even most small conditioners have a power draw of around 1000 watts, which means if you leave the air conditioner on continuously, then you can't use a hair dryer, toaster, or anything else. It would be better to have an air conditioner that uses less than 500 watts.

Existing alternatives:

Zero Breeze II - $1399 ($949 without battery) https://www.zerobreeze.com/

Cooling Style - $550 https://greenfunding.jp/lab/projects/2693

Both of these are quite expensive (considerably more than a decent in-window unit). Also, both the Zero Breeze I and Cooling Style are single hose solutions, which means they are not very efficient. (The exhaust cold air from the room, which creates a negative pressure which pulls in more hot air from other rooms).

Supplies

You will need:

1. Some tubing. I used 1cm silicon tubing.

2. A PC Cooling radiator.

3. Several computer fans (Depends on the size of the radiator)

4. Computer fan grates (if desired).

5. A 12 volt power supply or USB power supply.

6. USB to PC fan voltage converter (if using USB power supply).

7.USB or 12v pump

8. Aquarium chiller

9. Miscellaneous attachment hardware (hose clamps, screws, washers, attachment for the radiator, etc.)

Step 1: Assemble Fans & Radiator

You can find the fans and radiator pre-assembled as a kit, or buy them separately. I bought them separately and screwed them together.

I used the screws that came with the radiator and attached the fans, making sure that the direction of air flow was out through the radiator.

Once I verified fit and air flow , I removed the fans, and added them back with the grating on the outside.

Since I decided to use USB for my power source for the fans and pump, I bought two USB to PC fan converter cables. These step up the voltage from 5v to 12v. This might be slightly less efficient, but it also means the system is flexible, because you can always decide to run the fans on 12v later if you like.

After screwing the fans to the radiator, you need to screw in the connectors for the tubing, and attach your tubing to the metal barbs.

Once this is done, you can connect one end into a pump, stick the pump into a bowl of water, and you will be ready to test out the water flow.

I used a cheap general purpose USB water pump from Amazon, which had the capability to push water 3 meters. (I originally bought this pump for hydroponics, but it works just as well for this purpose). You could use a mains powered aquarium pump or a 12v general purpose water pump instead.

I put some ice in the bowl, and was able to verify the cooling effect once I powered the fans on.

Step 2: Procure and Hook Up Your Aquarium Chiller

There are four ways to cool the water that I can thing of:

1. Just use an ice pack. You could put it in one of those styrofoam coolers that has your water pump, and just cut two holes in the lid for the water outlet and inlet. This will work, but then you have to keep swapping the ice pack with one in your freezer.

2. Hack a mini fridge. I have seen this suggested for cooling fish tanks, but to make it effective, you would need to put copper tubing or something else heat conductive inside, and it would take up a lot of space.

3. Use a Peltier heat block. These are cheap, can work and is easy to build - but these are not very energy efficient - so you will save money in the short term but spend more in the long term. (Plus, more importantly - it's bad for the environment). These are a good idea for heating, however.

4. Use an aquarium chiller. These are a bit expensive, but you can find them cheap used, and sometimes you can also find Chinesium ones which might or not might work on sides like wish.com. I decided to go with a used one from a well known brand. Most of these don't work in reverse, though, so you can't use them for heating.

Step 3: Test Your Setup With the Chiller

I hooked up the outlet of the pump to the inlet of the chiller, and the outlet of the chiller to the radiator. The outlet from the radiator goes back to the reservoir.

This particular model of chiller lets you set the temperature down to 18 degrees, but it takes 3 minutes until it will start cooling.

It was at this point that one of my Chinchillas noticed the device and took a liking to it, staying in front of it the whole time I was testing it.

I tested my setup with the Chiller using just a pet circle, as shown below, and the temperature about 2cm away from the fans was about 22 degrees (which is what I set the chiller to), while the ambient temperature in the room was 26 degrees.

Step 4: Final Set Up & Tweaks

You need to decide how you will mount the cooler to the cage.

Mounting on the outside means you will always be pulling in hot air, so it may not be the best if the temperature difference is large. Mounting on the inside means needing to make sure your friendly critters can't chew anything they shouldn't.

Another option would be to keep the radiator mounted on the outside, but have some U shaped ducts which bring air from the inside to the back of the fans, such that air from inside is repeatedly cooled, and then the efficiency should be better.

Obviously you can't completely seal a cage like a refrigerator, because animals need fresh air, but you can put fabric around the bottom half of the cage to help keep the cool air in for longer (remember cool air drops, while hot air rises).

If you want to keep the compressor from running often, you can use a small styrofoam cooler as a reservoir to hold cold water. Another thing which would improve the efficiency slightly, would be to insulate the water carrying hoses from the air by covering them with some sort of insulating foam.

Remember that running this unit will actually heat up the room it is in, so you might want to run it in combination with an air conditioner. This would work well if, for example, you want your room to be 25, while your pets prefer 22.

You can also put the chiller in a box, and vent this to the outside, so that it is dumping heat outside instead of into your room - though be aware that most chillers (and Peltier junction) can only handle a difference of about 10 degrees. If you need more than that, then you might need to use more than one in parallel. For example, you could have a nice soundproof box which houses the cooler, and has two hoses, one taking air from outside and another pushing the air back outside. Computer fans can easily be used for this purpose.

Another interesting option, would be that instead of cooling the air, simply cool the floor of the cage itself (if you have metal drawers like my cage), or one of those marble stones. I mention this partly because some sources indicate that drafts are not good for Chinchillas. I can say that my chinchillas like to sit in front of fans in my room, and I know of at least one Chinchilla pet shop which uses fans, so clearly they are not so bad. (On the other hand, given that they have thick fur and don't sweat, fans should not have much effect).