Beating the heat without A/C... OR evap cooling on the cheap

***UPDATE*** A Word Of Caution***


We live in the inland northwest... beautiful country, mountains, lakes, mooses... you get the idea. As our climate is generally fairly mild, very few homes have central air or A/C of any kind. We can, however, get pretty hot in the summer months... gonna be around 90 degs for the next week or so... and the house can get pretty darned warm.

Fortunately, the humidity is pretty low... which is why this little trick works so well at cooling your living space with very little expense.

People living in the U.S. southwest are very familiar with this as many homes there are cooled in this manner...

It is called evaporative cooling... and it can be easily done on the cheap.

Mine uses a fan, an open window, a couple of old ratty towels and a water trough (actually a window planter box with the drain holes sealed)...

1. Find a suitable window: Only one prerequisite for this... it should open and even better if there is a screen installed.

2. Take your old ratty towels (I used two... old cotton ones big enough to cover the entire window opening) and pin them to the top of the exterior window frame so they hang down and completely cover the opening

3. Set your water trough at the base of your window (mine sits on an old wooden box) so the bottom of the towels sits inside

4. Cut vertical slits in the towels from the bottom of the window to near where the top of your fan will sit. The key to this is airflow, moisture wicking, and surface area... (one slit every 3" or so works pretty good)

5. Soak the hanging towels and fill your trough with water...

6. Set your fan in the interior window casing so it now pulls air through your soaking wet towels and crank that bad boy up

7. As the exterior warm air is pulled in, the water on the towels evaporates and cools the air... the towels will continue to wick water upwards from the trough (saves you from having go outside to soak them down every ten minutes).

8. Adjust your airflow. The trick to this is getting the air to go through at a rate which allows for rapid evaporation yet not so fast that the air doesn't have time to cool... the size and number of slits you cut also expose more wet surface area in addition to allowing airflow... (my fan on high was still pulling in warmer air... on medium, however, the air coming through is cooled by about 20 degs or so...)

9. Keep the towels wet... (I filled my trough twice yesterday and it was near 90 here)

10. Enjoy As I said, it was near 90 here yesterday... the warmest it got in our house was 73...

This represents the cooling potential of an evap cooler with temperature and humidity:



As you can see, the drier the air, the better this works... which is why they are so popular in desert climes. I apologize to you folks in the southeast... too darned humid for this to work very well...

We here in Britain are currently under the thrall of a very hot spell, and the temperature is frequently nudging past 30.c . The humidity here is... well it is high, I dont know precisely what the measurement is, because I do not think very well in these temperature and humidity ranges, meaning I am having trouble recalling where I usually get that information (it will come to me eventually).

The thing that is saving my (rapidly crisping) bacon at the moment, is that we actually have an evaporative air cooling device in our home at the moment. Its a unit which comes up to my thigh in height, about a foot deep at the thickest, and mounted on little castors at the bottom. Around back, is a detachable panel, behind which is a foam conveyor. This foam conveyor is dipped at one end into a tray full of water (we sometimes add ice, just to make the old nipples stand proud and remind us of winter). The foam conveyor allows the water to climb up to where the fan inside the unit is situated. It blows water cooled air into the room. Now, some might say "But TrueBrit, this method cannot possibly work in a humid climate!".

To those people I say "Nay! Forsooth! Tis perfectly wonderful in this humidity, for lo, though it cannot cool the entire bottom floor of our dwelling, verily does it chill the fellow who places himself directly in its flow!".

As you can tell, the heat has not made me any more sensible than usual. Also, some might say that its a bit of a cheat to have a pre-fab unit rather than modifying some old rags and garden equipment. To you I say, damned right it is, but we didnt buy the thing, it was a present from a friend of the family.

reply to post by TrueBrit


When I lived in southern Arizona, we had one house that only had the evap cooler... it blew really cold air even at outside temps of over 105... moreover, it costs less than half to run as compared to traditional A/C units, even when factoring in water usage...

Here in the inland northwest, it just doesn't make sense to buy a pre-fabbed unit. Only a few weeks of this weather per year, and usually only for a few days at a time.

reply to post by madmac5150


Well the friend who gave it to us lives about a mile down the road, and had just gotten himself a HUGE AC unit. The funny thing about it is, he only gave us the evaporative air cooler we have now, because the massive AC he has now takes up nearly a quater of his tiny living room. He purchases things he doesnt really need all the time though. I went over to his place once for the evening, just to play some video games and shoot the breeze, and at three in the morning he pipes up to me " Here "_____", do you fancy coming with me to Tesco? I think I am going to buy an electric bicycle !".

And so it was that four in the morning that morning, we were trying to get this bloody over complicated bicycle into the back of his car, ten miles from his place, for twenty mins before realising there was no way in the freaking world we were going to get the bike and the spare batteries into the motor. He ended up returning it, just becaues he couldnt get it into his car. Most random individual I have ever had the plesure of meeting actually.

I have to say though... I would be absolutley buggered without this evaporative air cooler, and I do mean, actually boned. Its been murderous hot here. I had to wring my shirt out, and it isnt as if my level of activity today was in any way stellar.

Someone sent me this picture a few days ago as a joke.
I wonder if this would actually work .. I am assuming the cooler is filled
with dry ice? Pretty funny!

I have seen it done, and they will blow cold air... until the ice melts anyway. I wouldn't recommend dry ice, especially if you have all of your windows closed... you could end up cold in a bad way...

I hate being too hot! I can deal with cold but not the heat. Best way to cool down is to sit in cool water. Take a cool bath or get a kiddy pool. People may think you look silly sitting in a kiddy pool but you will be cool.

Cold packs on the back of the head and neck. I have filled a stocking cap with ice and put it on my head while outdoors working in the heat. I was wet but boy did it feel good!

Just a few of my suggestions. Hope your day gets cooler!

reply to post by restlessinMT


Many years ago, while stomping around the VERY hot flight line at Luke AFB I picked up another trick... if you have to work outside in that heat, keep a wet wash cloth on the back of your neck. You would not believe how well it actually works... the water doesn't even need to be cold, it cools it self.

The stocking cap thing is a great idea as well! Probably could have saved me a lot of sunburns on my scalp...

I've been trying to find an alternative to compressor air conditioning and the need for high wattage motors.
I'm studying up on off grid electric but it's too hot and humid where I live. The solar power to run an air conditioner would cost more than a new car.

Gas or propane compressors exist but the ones available are too large for a small, efficient house.

Swampers are not effective with high humidity.

There are some good split units with variable frequency drives but they still draw too much power for solar.

A grid tie system is expensive and redundant because even if you make enough power to sell back to the grid it won't even cover fuel surcharges.

Not sure what to do with it.

**WORDS OF CAUTION**

I had a little incident with my evap cooling contraption this morning. When I first wet my towels down, I close my window and use the garden hose to spray the entire thing down from outside. The window is a modern one, triple paned glass and sealed casing... so, I went back inside, cranked up my coffee pot, opened ATS (gotta have priorities ya know)... then opened the window and plugged in my fan.

What happened next?

A not so subtle bzzzhhzzzhhzt noise from the fan, followed by a very bright orange spark from the fan motor housing and a wisp of ozone smelling smoke... oops.

I unplugged the offending S.O.B. just as quickly as possible, then opened up with a string of expletives that would make a sailor wince... I think I even heard a gasp from my guardian angel for this little outburst...

Now, my years of expertise with troubleshooting electrical and electronic systems took over and I began to scrutinize what had happened... didn't have to look all that far. The motor windings were scorched and wet...

I re-closed the window and noticed a tiny drip of water inside the window... hmmmm.

In best "Mythbusters" form I tried to re-create what had happened... I had Mrs. Madmac watch the inside of the closed window while I hosed it down from outside... nothing... no leaks... until...

I tried spraying the top of the casing from an angle below horizontal... and it happened. One tiny little stream of water made its way inside... and the rest, along with my fan is now history...

In summary... this little trick does work, but if you attempt it... exercise caution and keep your fan dry