George Kong

Ollie Puddlemaker wrote:

George - Some other ways, and this just might lower the temp even more, nothing wrong with having multiple methods, this first would be to use a shelving unit PVC, plastic, wire, whatever you have available and drape burlap/loose-weave material over it, top to bottom. You would have your fragile items placed apart from each other on the shelves keeping good air flow, on the top most shelf you would have a water reservoir that would re-hydrate the burlap as it wicked downward and dried and evaporated the moisture, cooling the interior. It works best if there is some kind of a breeze to blow thru. Drawback is that it can use a lot of water and you can't let it run dry...

Last idea to try, make up a solar funnel cooker, but use it at night pointed toward deep space and cool thru radiant cooling. When the night sky is clear and cloudless this will freeze water in jugs inside an insulated cooler. Good coolers here in the States can hold ice for 5-7 days, given you have an open, clear sky, properly aimed and un-disturbed. then easily you have an excellent passive method.

Thanks, Ollie! Your first method sounds a lot like the air-coolers they have here in India -
http://en.wikipedia.org/wiki/Evaporative_cooler

I had one when I lived here some years ago and it works very well, but rooms become very damp from the moisture.

Your second idea sounds like sci-fi but is worth a try.

I cemented my inner pot to my Zeer fridge so it doesn't float and filled the sand with water. It still doesn't drop below 25 C, or about 10 degrees below air temps. One unexpected benefit I got when I moved it inside, is that the evaporated moisture now blows out through the nearby fan, cooling my room, perhaps like the evaporative cooler you described.

An average of 10 C would be great! Surprisingly, nobody here has ever heard of these pots which could make life so much easier for the villagers. The town people think I'm backward because they all have electrical fridges and scoff at the Zeer pot. Moreso because my prototype isn't the spectacular success I promised. But I imagine the villagers would be happy to be able to keep their tomatoes, milk and even insulin at cool temps even without a fridge. They could also make cold water while working in the fields, etc. I don't suppose this will work in winter though. I'm interested in keeping veggies (and beer!) fresh longer in case of global collapse. I'm one lazy doomhead.

Thanks, Ollie. My pots are new and still quite porous but I'll keep it in mind. I'll also have a look at Hypertuffa as I hope to use the same Zeer pot principle to cool the air in my house in the Caribbean. I have in mind a long tube in a wet trough (made from Hypertuffa perhaps?) running around the house for perhaps 180 ft. rather like the buried air tubes but above ground for evaporation. Buried air tubes won't work in the Caribbean as we have no cold seasons and very little temperature variances. I'll be happy if the incoming air could be around 23 C as it's a/c for free. I realise the Caribbean is very humid, but we have year-round sun and water evaporates off the roads like magic, so it might work. So far though, my Zeer pot hasn't been very promising. Does anyone have any idea what temperatures they cool to?

Thanks Kathy, but the pots here are unglazed like these -
http://blogs.gonomad.com/traveltalesfromindia/files/2012/01/Clay-Pots-or-Ghara.jpg

This morning I decided to put more water in the sand so I wired the inner pot in place and filled the outer pot with water. The inner pot floated up and defeated my attempts so I've now cemented the inner pot in place and will try again when the cement has set. Reading about your adapted cooling system, I now wonder why I need to put sand in between the two pots. If evaporation is all that's required, why can't I simply pour water in between the two pots, just as you do to cool your drinks?

I'm currently in Udaipur, Rajasthan, (on the edge of the Thar Desert) and thought I would try the Zeer pot fridge. I had to adapt two Rajasthani round-belly Ghara clay pots (which they use to cool drinking water by evaporation) because that's all they have, but the principle is the same. The larger pot had to be broken to allow the smaller one inside but the heights match perfectly. The climate here is perfect (hot and dry) and my pot is just outside the house under the eave for maximum evaporation. But it ain't working! Outside temperatures are between 30 and 36 Celsius, pot interior remains at 25 C and that's when I had a bottle of water inside to regulate the temps. Without the bottled water, the interior temperature remains at 29 C. I believe it should cool to 10 C when working properly. I pour between 500ml - 1 liter of water per day in the sand; too much water and the inside pot will float up. It's such a simple fridge what could possibly go wrong? Comments and suggestions, please?