Almost Free, Portable, Indoor, Home-made Evaporative (Swamp) Cooler




Introduction: Almost Free, Portable, Indoor, Home-made Evaporative (Swamp) Cooler

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It's easy to have a portable, indoor, evaporative cooler for your home -- just go to Home Depot and slap down $1,000. Heck, they'll even deliver it today! What's not to like about that?


But, FYI, you can make a portable, indoor, evaporative cooler for your home yourself for little or no cost depending on what you already have on hand. All it takes is your time -- first designing and then building it. I had most of the parts and tools that I needed so it cost me about $15. OK, if you add in the fact that I had paid, at some point in the past, for the many, other "left-over", on-hand, old parts that I had, it probably cost me $40. I won't include the cost of my tools, electricity, my time, etc. So excluding these last three items, you can built this for anywhere from $0-$100. That would be $0 if you already have everything (not too likely), $50 if you have most things on hand or buy them used, and $100 if you don't have any of the parts and buy all of them new.

At the bottom of each page, I'll provide three dollar amounts (to give you a running estimate of your costs), such as ($0, $0, $0). The first number, in bold, is what it cost me to buy things I needed for the project. If you have the items I didn't, then you are one step ahead. The second number, in italics, is what I estimate it cost me -- including the original costs for the parts and pieces I already had on hand. This estimate is just a "ballpark" figure -- how do you estimate the cost of one teaspoon of PVC glue or three cups of paint from a gallon can that was bought, probably on sale, 15 years ago? Still, you can use this as an estimate of the cost if you buy (or use) old, used parts. The third number, underlined, is what I estimate it will cost you if you buy all of the items new. And, of course, this will vary as well depending on what you buy, when, how, etc. If you buy a quart of paint and only use half of it, it's difficult to price it right!

To begin, let's start with the theory of the whole thing -- which is really pretty darn simple. Just look at the diagram above. All you need to do is create a way to pull hot, DRY air through a wet, permeable surface -- and you end up creating cooler air. Nothin's complicated 'bout that! In fact, during the 1930's, the Dust Bowl resulted in the largest migration in American history. Many Okie's had to pull up their stakes and move to California to find work. If they were lucky, they found work toiling all day tending crops under the blazing San Fernando sun. When the long, hot day was over, they would hang water-soaked blankets on clothes lines around their open-air campsites. During the evening, the dry Santa Ana winds would cool them off! (Hot Tip -- read Steinbeck's "Grapes of Wrath" or watch the movie with Henry Fonda).

Take a look at this US map to see if a swamp cooler will work in your area.

But enough of history. The diagram above only shows two elements in the cooler that I designed. It is best to think of this as FOUR, simple, interconnected "systems".

The first is on the left -- the "watering" system. This consists of water slowly dripping down (thanks to our free-for-all friend, Gravity) through some sort of porous material or membrane through which air can flow. Nothing more.

The second is on the right -- the "ventilation" system. This consists of a means of pulling (basically sucking) air through the wet, porous membrane just mentioned. In this diagram it is a fan (no applause please).

The third is not shown. It is the "power" system. This consists of a way to power the water system and the ventilation systems. This can be accomplished with standard, 110 volt AC household electrical current, solar power, or any other means (such as a husband or boyfriend on a treadmill).

The fourth is also not shown. We will call this the "cart" system. It is just a simple way to move the other three "systems" around together, at the same time, safely and securely indoors -- EVEN in the dead of night!

I think of my creation as the "Beverly Hill's evaporative cooler", but most will probably refer to it as the "Beverly Hillbillies's swamp cooler." Whatever -- I'll let you be the judge.

To start, let's take a look at the parts that you will need -- broken down by each system. Keep in mind that the parts that you will need will depend on what you already have on hand, what is available to you, as well as how you want to design your system. Your cooler won't look like mine because you will be using different parts to meet your particular needs, available parts and situation.

Step 1: ​#1 -- Ventilation System Parts:

The graphic shows my setup when looked at from above. It shows a fan sitting on a wood panel sucking air in through a wet, evaporative pad.

The three pictures show pretty much everything you need to complete this project. It's not much and as you can tell, most of this stuff is just left over junk!

Building one yourself basically starts with the fan because it's easier to adjust everything else to the size of the fan, rather than try to find a fan to fit all the other parts.

There are a LOT of fans out there. Many sizes and shapes -- and colors. You can design a system around any of these, but it will be easiest to design a system based on a square or rectangular fan -- which are available in many sizes. But check the corners -- some are very square and some more rounded. The more sharp and square the corners, the better. These can be purchased new for very little money, but they are usually available at thrift stores for only a couple of bucks. I got my 22" x 22" square fan at a thrift store a few years ago for about $3, I guess.

Most fans come with an adjustable speed control, like mine, but this might not be important to your project, as you will see.

Most fans have a metal case around the edge with plastic slats covering the fan blades on the front and rear. The AC electrical wire usually comes out the rear (intake) bottom of the fan.

These fans usually have a plastic handle on the top of the case with holes in the metal. You can leave it "as is", but it's best to remove the handle (it won't be needed) and cover the holes with packing tape to prevent air from circumventing the watering system.

You'll have to throw in four small nuts & bolts (and washers) to hold the fan down, but that's all there is to the ventilation "system". I already had a fan and the other stuff, so the

COST AT THIS POINT: $0, $3, $20

Step 2: #2 -- Watering System Parts:

This graphic shows my setup when looked at from the side. It shows a fan on top of a tub (which holds the water) sucking air in through an evaporative pad (while it is being soaked with water).

Unlike the ventilation system, the watering system consists of more than one part:

Evaporative pads -- these are soaked with water by means of a dripper pipe or tube (see below). There are many commercial types available, and which you choose will depend on your situation. I chose the Aspen Snow-Cool pads because they are easy to get, highly regarded, and most importantly, you can cut them to whatever size you need (see first photo). They are about 1" thick and come in a variety of sizes. I chose the 20" x 22" which was the closest match to my system and required the minimum amount of cutting. These can be cut with a heavy-duty pair of scissors. They are literally small, shredded strips of aspen wood held together with a very fine, plastic, hard-to-see mesh on both sides. I have no idea how long these, or other, pads will last before needing to be replaced due to rot, mold, fungus, odor, old age, etc. We will have to wait and see, but replacing them is really pretty easy if you design your system carefully from the start.

Holders for the pads -- You need something to hold the above pads on the back of the fan that will let a lot of air through it and the pads. I thought about it for a while. It was Spring and I was planting seeds in my greenhouse. I put the seeds in pots and put the pots in pot holders (AKA flats or grates). These tough, plastic grates are holders for pots and are perfect for the job -- if you get the right size for your fan. They come in a variety of sizes and styles and plastics (see photos #2 & #3). What is needed is one or two that fit your fan, are a durable, yet flexible plastic, and have a wide enough edge to put screw holes in (to hold it to the back of the fan). Some are open on just the bottom, and some are open on the bottom and sides.

These are used at nurseries, home improvement stores, super markets, gardening shops, hardware stores, grocery stores and even some pharmacies. What do they do with them at the end of the season? Probably most are thrown out. They can't recycle them because the type of plastic is not marked on them and they are covered with dirt. Some may get sent back to the distributor, but what do they do with them? Hint -- go back three sentences. In short, if you go to your local "shop", they will give you as many as you want -- for FREE! Take measurements before you go, or take a few samples home, or just go (with a tape measure) and see what they have.

I already had a BUNCH, so I selected two that perfectly fit on the back of my fan (see photo #4). They were open on the bottom, closed on the sides, but had two openings on the top and bottom sides -- which made it easier to drip water through them (see below).

Tub for the water -- You have a LOT of options here -- laundry baskets, storage bins, food coolers, trashcans, etc. First, is the size. You can get all of these from small to large, tall to stout, wide to narrow. Get one that is wider than your fan so that it will be able to catch all of the water as it drips through the pads (see diagram above). Don't get a tall one, like a kitchen trashcan, because these will be easier to knock over. Many have holes on the bottom or sides, sometimes small, or drain plugs. Avoid these. Others, like laundry baskets has slats on the side. Stay away. Look for cracks or signs of stress, especially in hard plastic. Don't try to make any repair. Check for the type of plastic on the bottom. The #5 PP is the best and strongest and will last the longest. Just make sure it is very rugged, thick and sturdy. Like fans, you can get these new or for a couple of bucks at a thrift store. Make sure it has a wide enough rim around the top that will allow you to drill a few holes to attach the tub cover (see last photo). My tub will hold 18 gallons, but I try to keep it about half to 2/3 full -- that's still about 100 pounds of water!

Cover for the tub -- You need something to cover most of the top of the tub and hold the fan assembly (see photo #8). I had a left-over piece of 3/8" plywood that just needed a little trimming. It should cover about two-thirds of the top of the tub. The part it doesn't cover is where the water drips down out of the cooler pads back into the tub (see diagram above). You will want to cut this to size (or a little over-sized) and, if it is wood, paint it with an epoxy, an oil-based or marine paint or polyurethane because it will be exposed to high humidity and is likely to get wet. Latex paint is water-based and will just lead to trouble. On the top of this cover you'll need to add a small door (see diagram on previous page) to access the pump, clean out the tub, etc. See photo # 7. All I did on mine was cut a rectangular piece out of the plywood panel with a jigsaw and put it back in place with a piece of piano hinge and a knob (see photo #6) -- both of which I had. You can also use this door to check the water level. You'll need to check the water level often, at first, to see how much water is being used in your set-up. Mine uses about 4-6 gallons a day -- if it is used all day -- so I add a couple of gallons every 4-6 hours of use. If the water level gets too low, the pump will dry out and then quickly burn out -- so don't forget the check! You can use the door to add water or you can drill a separate hole off to the side (see diagram on previous page) and add a funnel (or the top of a used, empty, plastic bottle) to add water.

Water circulation parts -- This consists of basically three parts -- water pump, tubing, and dripper pipe. The main part is the water pump. There are a lot of options here and it is easy to get confused. First, there are underwater pumps, called submersible pumps. There are also water pumps that are NOT underwater. You can use either, but life will be easier if you use a submersible type. All water pumps comes in different "strengths" -- basically how much water can they pump, how fast and how high. The "how fast" part is usually rated in gallons per hours or something similar. The needs here are very minimal so there is no need to deal with that aspect at all. The second is how high it will pump. This is often referred to as "height", "rise", "lift", "head", etc. However, the listed lift depends on the width of the tube or pipe it is pushing water through. The narrower the pipe, the higher it can go. The manufacturer lists the height based on the output diameter of the pump -- but they often don't mention what the output diameter of the pump happens to be. The pump I have came with an adapter to allow it to be used with either 1/4" or 3/8" tube/pipe. Plus, some pumps are adjustable so that you can control exactly how much water it pumps.

What's most important here is the lift, but again, the height needed is small. Measure from the bottom of the tub to the top of the fan. In my case it was about 3' 4". So all I needed was a pump with a 1 meter head. I got a new, submersible, adjustable model on EBAY for $5. It is only about 1.5" x 2" x 2". Your local aquarium shop (Petco, Petsmart, etc.) will have a lot of choices. You don't want a pump that is too powerful because you'll just be wasting electricity -- and will likely get water all over the place!

You'll also need a piece of pipe (or tubing) to lay across the top of the evaporative pads and drip water into them. I opted for a piece of rigid, 1/2" PVC pipe because that's what I had on hand. All you need is a piece that is the width of the fan -- in my case 22". Unfortunately, you can usually only buy PVC (or ABS) pipe in eight foot lengths. You could even use copper pipe, I suppose. But whatever you use, you need to drill 1/8" holes in a straight line, along the entire length, spaced about 1/2" apart. Make sure you don't drill holes where the water won't drip onto the pads. Close off one end of the pipe with a cap, and place an adapter(s) on the other end. I used two adapters. One is a 1/2" PVC pipe to standard 1/2" pipe thread, and second, a standard 1/2" pipe thread to 3/8" tube adapter. But there are many ways to skin this cat and adapters are easy to get.

And, of course, you will need to devise a way to attach the pipe to the grates. I attached the PVC pipe to the top of the pad frames by using three plastic cable/wire ties (see last photo), but twist ties or other clamps could be used just as well. I got a pack of 100 ties at Harbor Freight several months ago for free. I never knew what I would use them for, but they were free, so I took them. The regular price is probably in the neighborhood of $0.50. I still have to figure out what to do with the remaining 97!

All that is left at this point is to connect the PVC dripper pipe to the pump. I had four feet of 3/8" tubing in my left-over aquarium supplies so that is what I used. You should be able to get the right tubing for your pump at an aquarium shop for next to nothing, or if you know someone who works at a hospital or medical clinic, have them pilfer an about-to-be-trashed, left-over length of surgical tube. There are various tube adapters, if you need to use one, to switch from one size tube to another.

You'll have to throw in about six thin, small nuts & bolts (and washers) to secure the cover to the tub, as well as a few dabs of PVC/ABS glue (assuming you use PVC/ABS pipe). I had all of the above parts/materials on hand, except for the Aspen Snow-Cool pads (I only needed one but I got the best deal on a three pack) and the water pump -- so the total cost at this point hasn't gone up that much.

COST AT THIS POINT: $15, $30, $60

Step 3: #3 -- Power System Parts:

Mine is a very simple set-up and yours will probably be different than mine because you have different needs, access to different parts, etc. In any event, if you are new to electrical wiring, it's best to take a trip to your local library and check out a basic home-wiring book. The 15 minutes it will take you to learn the basics will be well worth it.

Your design can be even simpler than the simple set-up I devised. Take a look at this diagram of my design (in this diagram, the black wires are HOT and the red wires are NEUTRAL).

Switch for the fan -- This switch is optional. You can always just plug the fan directly into the wall and control the fan speed with the fan controller -- assuming it has one. That will make your life as easy as possible. Most fans have an ON/OFF switch so you can just leave it plugged in all the time. I opted to use a rheostat (dimmer) switch to control the fan. This provides greater adjustment to the air flow and I can leave it plugged in all the time. My approach was to put the ON/OFF switches for both the fan and the pump on a single panel in the front, but that is only one way to approach it (see second photo).

Switch for the pump -- This switch is also optional. You can always just plug the pump directly into the wall and control the pump volume with the pump controller -- assuming it has one. That will make your life as easy as possible. Most pumps don't have ON/OFF switches so you need to plug it in each time you use it. I opted to connect the pump to a switch so that I can leave it plugged in all the time. My approach was to put the ON/OFF switches for both the fan and the pump on a single panel in the front, but that is only one way to approach it (see second photo).

Electrical box & cover for switches -- If you decide to use one or more switches, you will need an electrical box and a cover of the appropriate size. These come in various sizes and shapes, in metal or plastic.

Wiring, caps & screws -- Depending on your set-up you will probably need about 6-12 inches of electrical wire, two or three wire caps and a couple of screws to attach the electrical box to the tub cover -- as well as a wire cutter/stripper. If you go the route with a switch box, you will need a length of wire with a plug on the end. That's not a problem because you'll be cutting off the wire to the fan and you can use that!

I had all of these parts -- saved left-overs from other projects -- but even if you don't have any of them and you buy them new, it won't cost too much:

COST AT THIS POINT: $15, $40, $75

Step 4: #4 -- Cart System Parts:

Cart for the tub -- this is just a "vehicle" to keep everything together and move everything around at once. It consists of a little bit of wood and four wheels (see photo #3). The cart is really OPTIONAL. Your don't need it to operate the cooler, it just makes it easier to move it around. The entire cooler, when put together, can easily weigh more than 100 pounds, but if you are absolutely certain that you won't need to move it, just skip this step.

Wood -- First, it is a piece of plywood or chipboard for the bottom of the cart. It just needs to be a little bigger than the bottom of the tub -- to include the edges (see photos #1 & #2). Second, the edges can be any appropriate width -- 2" to 6" -- with a thickness from 3/8" to 1". I had some 1/2" chipboard and an eight foot section of 1" x 4" -- which is actually 3/4" x 3.5" -- so I went with that.

Wheels -- You'll need four -- one for each corner of the cart.Never attempt a tripod system to save cost. You can use wheels of any size, but they have to be able to support the weight of the entire system -- WITH WATER. The water is the heaviest past, so we can be talking about 100 pounds -- that's 25 pounds per wheel.

The wheels also need to revolve -- besides rotate. If they don't revolve, all you can do is move the unit forward and back. But the problem with revolving wheels is that the system has a fan which is basically a propeller. If all four wheels revolve, when the fan is turned on, the whole contraption can, and will, move around the house. Not a good idea unless you happen to want gallons of water going down your staircase.

What you need will be at least two wheels that lock -- so that they cannot rotate. That will keep everything from moving away from where you put it.

The wheels don't all need to be the same size. Mine weren't. I had two large wheels and two small wheels. That's no big deal but you will need to create a spacer for each smaller wheel to make sure it will be at the EXACT same level as the larger wheel -- see photo #1. Otherwise you will be in deep "water".

Some wheels are screwed on, some bolted on. Mine were both. It's not important, but make sure the screws don't stick through the bottom of the Cart. That could puncture the Tub and you will be in deep DOO -- as well as water!

Extras -- You'll also need some paint for the cart and some nuts and/or screws depending on your wheels. There are a few places you might want to check out for any parts you might need. First, there are always thrift stores -- even in out of the way places, like Thermopolis, Wyoming and Tombstone, Arizona. Habitat for Humanity also runs outlets which sell mostly building materials that are left over from their many house-building projects. On-line, there are websites, such as, where people in your area offer stuff they don't need -- free of charge! And many cities have organized "chemical reuse" programs where anyone in the area can drop of their left-over paint, pesticides, herbicides, solvents, cleaners, acids, bases, etc. and anyone can drop by and pick them up for free! Many colleges and universities offer their (safe) unneeded chemicals to the public at the end of the school year for little or no money. It's cheaper for them, rather than paying to have them "disposed of". I picked up two pounds of unopened silver nitrate (reagent grade) from the University of Colorado a few years ago for FREE -- it's street value is about $2,000!

I had all of the parts I needed for a cart -- saved left-overs from other projects -- but even if you don't have any of them and you buy them new, it won't cost too much:

TOTAL ESTIMATED COST: $15, $60, $100

Step 5: Putting It All Together -- Cart System

To a certain extent, you can work on each system separately, but you have to make sure as you go along that the parts from one system will correctly, physically mesh at the connection points to the other systems. Which system you start on first is really up to you. I built the cart first so I'll describe that first. You could probably get the entire thing done all in one day -- assuming you have all of the parts on hand and don't need to stop to eat -- but perhaps a better approach is to plan your system ahead of time, buy any parts you need during the week, and then spend just a few hours on consecutive weekends putting each system together.

First, I found an appropriate fan and a tub that was slightly wider than the fan. I had a good selection of both on hand to choose from. Next, I took measurements of the bottom of the tub and selected the wood that I would need and had on hand -- one piece of 1/2" chipboard and a piece of 1" x 4" lumber (actually, it was a piece of Weyerhauser, factory-painted, "pressed sawdust" -- as far as I could tell -- but it was unused and found it in a dumpster several years ago). I was happy to press (yuk, yuk) it into service.

I cut the chipboard to the correct size. Be careful here because most tubs are tapered and this needs to be taken into account. Next, I drilled several screw holes around the perimeter, 3/8" from the edge. I then cut four pieces out of the Weyerhauser board to the correct lengths, and screwed then in place. A few more screw holes on the edges gave me a good sturdy tray. I then painted the top and sides with a good oil-based primer.

All I needed to do, after it was dry, was add the wheels. I had a bunch of wheels but not all of them were good for this job. Some were too small, some too big, some too flimsy. Some didn't revolve, so I would only be able to move the cart forward and back. Some of the ones that did rotate would not lock in place. That's important because the fan could move the cart if the wheels aren't locked.

I had two larger, revolving, bolt-on, locking wheels and two smaller, revolving, screw-on, non-locking wheels that could handle the job. I created two 1" spacers for each of the smaller wheels to make sure that all of the wheels would be at the EXACT same level (see photo #1 of the bottom).

All it took was some careful, thoughtful measuring (measure twice, cut once), and everything fell into place. Cart system done!

Step 6: Putting It All Together -- Ventilation System

Next, I decided to tackle the ventilation system. Remember that it is basically just the fan, but it needs to be attached to the tub somehow. Along the way, it will later be attached to the cart, watering, and power systems, but we don't need to think much about that immediately.

I found a piece of 3/8" plywood that needed just a little bit of trimming to fit over two-thirds of the tub (see Photos #1 & #2). The other third needs to be left open so excess water will drip back into the tub (see diagram). Cut the wood slightly wider than the tub because you'll bolt the panel to the rim of the tub with nuts and bolts -- see photo #3.

But first things first. You can't simply bolt the panel to the tub because the fan also needs to be bolted to the panel and if the panel is bolted to the tub, you can't get underneath the panel to attach the fan. So first, you need to temporarily attach the panel to the tub. Find six or seven bolts that are thin enough to fit in the rim of the tub and long enough to cover the depth of the rim and the panel. Then carefully determine where to drill holes (a tiny bit larger than the bolts) in the wood and the rim underneath. Placing a bolt in each hole as you go along will help keep the panel in place. No need to put the nuts on just yet.

When that is done, remove (at least) the rear screen from the fan and position the fan on top of the panel. The rear of the fan should be just over the edge of the panel (see last photo). Then mark four spots on the bottom of the fan for drill holes (see photo #4 with the fan blades). Find four nuts (and bolts & washers) that are long enough to reach through the bottom of the fan and the panel. The width is not too important.

Mark on the panel where the fan is, then remove the fan and place it on a spare piece of wood. Drill holes slightly wider than the bolts. Put the fan back in place on the panel and make a mark on the panel through the holes. Then remove both the fan and panel, and drill through the panel where it is marked.

Don't bolt the fan to the panel or the panel to the tub at this time. It will be easier to work on them and attach the other systems if they are kept separated, but at this point, the ventilation system is pretty much done.

Step 7: Putting It All Together -- Watering System

Next is the watering system. There is a lot of possibility for variation here but you can take what I did and change it as needed.

I found two grates that fit my fan perfectly. See photo #1. No modification was needed, but I needed to use two grates. I expected that I would need to drill extra holes in the rear rim of the fan, but I didn't. The rims of the grates on the top, bottom and side matched up perfectly with the screws already in the fan. All I needed to do was remove the rear grating on the fan, line up the two gratings and drill small holes (slightly thinner than the screws) in the rim of the gratings -- one on each top, one on each bottom, and one on each side. The gratings are stiff enough to stay snuggly in place (see photo #2). You can add additional screw holes if you want or if your rims don't match up perfectly with your fan.

But before I attached the two gratings, I needed to do a few things.

While I had the rear grating removed, I opted to clean the motor. It is old and was dusty (see photo #6) -- nothing a good vacuuming could not solve. Also, I moved the electrical wire from the rear of the fan to the front, since that is where the switch will be (maybe not, in your case). If you do move the wire to the front, make sure that it is placed well out of the way of the fan blades!

I then temporarily placed the rear fan panel back on the fan and placed the grates on the back of the panel. I lined up the rim of the gratings with the screw holes on the fan. I chose a drill bit slightly smaller than the screw holes on the fan (see photo #7) and drilled through the grating rims.

I also needed to make some minor modifications to the grates (top and bottom). As seen in photos #1 and #3, my grates had two rectangular holes in the top and bottom. Yours may or may not. In either case, there needs to a an open strip along the top, a little wider than the dripper pipe, so water can drip onto the top of the pads (see photos #8 & #9). Likewise, you need to have the bottoms open enough to allow the water to drip into the tub, but at the same time, keep the pads from falling out the bottom! So cut the top(s) and bottom(s) of your grates in a way that keeps them structurally sound and will still let the water circulate where it should.

Next I measured the interior of the gratings and cut the Aspen pads to fit (see photo #4). Make sure you don't cut them too small. They are compress easily and you press them into the grates -- they do not swell when they eventually are wet. At first I tried using two pads in each grate thinking it would increase water circulation. I learned that it did, but it decreased the air flow far too much. One layer of Aspen pad is all you need.

Then, I placed the Aspen pads in the gratings and screwed the rear fan panel and gratings back onto the fan.

Actually, the grates did not perfectly match in the middle. There was some slight bowing and separation (see photo #3). I solved this by simply adding a couple of twist ties to keep them nice and snug.

I placed the end cap on the PVC pipe and my pipe-to-tube adapters on the other. I placed it on top of the gratings and marked where I wanted to drills holes -- and not. Then I drilled 1/8" holes about every half inch and cleaned them of debris with a small file. I did not attach it to the gratings just yet.

Finally, I bolted the fan to the tub cover and then bolted the tub cover to the tub and placed it all in the cart.

Step 8: Putting It All Together -- Power System

The only thing left is to power this puppy up. Your wiring will undoubtedly vary from my set-up.

First, I attached the electrical box to the tub covering panel. Position far enough away from the fan so as not to block the removal of the screws on the front panel or the panel itself. The box only needed just two screws to keep it in place, and I drilled a hole through the panel underneath the box -- to run the wire to the water pump.

I cut the cord from the fan and used it to run from the wall outlet to the electrical box. I also cut the plug off of the water pump wire and stripped the wire to attach inside the electrical box. You just need to cut and strip these wires to the correct distance in your set up.

Depending on your fan and/or pump you may need to check for polarity. In other words, you want to make sure the fan and pump are turning in the correct direction when turned on. If not, just switch the wires!

Next, attach your tube to the pump. Put the pump and the tube inside the tub. My pump has four little suction cups on the bottom so it will stay in place on the bottom of the tub. Run the wire into the electrical box through the hole you drilled and run the water tube out the back and up to the side to the top of the gratings.

Next, connect all of the wires in the electrical box, as shown.

Finally, connect the tube to the PVC pipe. Position the pipe so that the dripper holes are on the bottom and tie it in place with cable ties or whatever you have. You might need to drill a few small holes in the grates to get a good placement. I only used three ties, but you can use as many as you feel are needed.

Well, that's all folks! Fill 'er up with water and turn it on. Watch for any water missing the pads or dripping out of the tub. It should be easy to make any necessary adjustments / fixes. If too much (or too little) water is dripping out, turn down (or up) the pump (if it is adjustable), use a stronger or weaker pump (as needed), or use a pipe with smaller or larger holes (as needed). You don't need much water dripping out, and it should NOT be a stream or spraying out! What you want is a good steady drip. If the drips are stronger or weaker at one end of the pipe, you can redrill the holes on the weak end with a slightly larger drill bit.

Changing pads just means unscrewing the gratings from the back (in my case just six screws) and putting in new pads cut to size, of course. This is best done with the water removed and the fan laying flat. To empty and store the cooler for the winter, unbolt the tub cover and remove the fan (still attached to the tub cover). Then roll the tub into the bathroom and bail out the water into the bathroom tub.

I have always had both an indoor and outdoor thermometer. You might want to make that small investment if you have not already. It will help you determine when to use your cooler. In hot weather, I normally keep one or two windows open at night to help cool down the house (I live in a safe neighborhood). When I wake up it is usually about 60 degrees outside and 70 degrees inside. I then open more windows and doors and turn on the cooler and even an extra fan or two to help get the cooler outside air in.

I added a cheap aquarium thermometer to the front grid of the cooler fan to check the temperature of the air. I found it pumps out 50-something degree air early in the morning. The cooler, the Westerly wind, and the extra fans help get the house down into the 60's.

When the temperature outside becomes hotter than the temperature inside, or when the temperature inside starts to go up, I close the doors and most of the windows. I'm cooling a 1,000 square foot area of the house -- not the entire place. I keep a small window open at each end of the house and the cooler is located a few feet inside the western window (the windward side is where the hot air normally comes in during the day). It seems to keep the inside of the house 10-15 degrees cooler than the outdoor air, so when it is 90 outside it is about 75 inside. Not bad for only $15!!! You'll need to play around with where to best position the cooler and how wide to open the windows -- too much hot air and the cooler can't keep up. Too little hot air and the cooler doesn't have enough to work with. But then, I've had pretty much the same sort of problem for most of my life!!!

And, of course, if no one is at home during the day, you'll need to consider how to deal with two issues. First, security; can you safely leave two windows open -- even a crack -- all day long? Second, is your tub large enough to hold enough water to last all day long?.

Finally, I've discovered two things you will probably have to deal with. First, miscellaneous stuff, like bits or shreds of the evaporative pads, will tend drop into the tub and accumulate. This can be a problem, especially if it gets into the pump. It could block water flow and or get stuck in the pump blades. Not good. One way to deal with this is to open the trap door and looks for "stuff" with a flash light. I use a fish net -- from my fish tank -- to grab the "stuff". These are cheap at the aquarium store or you can devise another approach. MAKE SURE YOU UNPLUG THE UNIT BEFORE YOU PUT YOUR HAND IN THE WATER!!!!

Second, at some point, you will discover some slippery slime/algae growing on the sides of the INSIDE of the tub and on the pump tube and wire. This won't happen overnight, but you might need to deal with it in some way before the summer is over. There might be products out there to deal with slime, but I'm not knowledgeable about them. Any suggestions would be appreciated. I thought of bleach -- which should work, just like in swimming pools -- but that would smell up the house! Maybe there is an odor-free bleach. I'll drop in to the local swimming pool store when I get a chance.

Feel free to add any suggestions, ideas for improvement, or other related issues!

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    9 Discussions


    3 years ago

    I bought a large barn fan (a big expensive right there) but I am going to use these instructions to add the evaporative cooler element to it. Thanks.


    Reply 3 years ago

    My fan is a typical, 2x2 foot, window fan -- and is square, making it easy to work with. All the BIG BERTHA fans I've seen are round, and although a round fan can work, you will need to cut an appropriate-sized circle in a sheet of plywood (or whatever) to fit with your dripper system. I see no reason that it would not work well for a LARGE open area, such as a barn, but you need to be in an area with low humidity. A smaller extra fan -- at the other end of the room(s)/area -- really helps, I've discovered. Also, those large fans can be as strong as a tornado. You don't want it sucking the complete dripper system through its blades -- let alone wasting electricity, if you don't need to! So you may need to reinforce the dripper system mattes, and/or add a rheostat to the fan. Much of the time, I run my fan on LOW, and that's all I need. It's getting to be the end of Summer, so I'll be putting mine away again -- after TWO YEARS of great, ALMOST FREE, cooling. GOOD LUCK.


    Reply 3 years ago

    Thanks for your thoughtful comments. It is a round fan. And I didn't think about it's strength. Well I have a lot to think about.
    I am in a hot area of California so it is very dry and the evaporative cooling works well. They sell giant barn swamp coolers but they are expensive.


    Reply 3 years ago

    You're right. If I bought a comparable cooler -- to the one I made -- it would be $500-$800. Mine cost me, maybe, $50.


    4 years ago

    Today, when I was walking home from my early morning jog, I saw a Portable, Indoor, Factory-made Evaporative (Swamp) Cooler put out by someone's Denver City trash cans. The
    City didn't pick it up because it wasn't inside a trash can, but it was
    obvious that the owner was throwing it out. So I took it home. I
    figured it must be broken, but maybe I could fix it given my knowledge
    of evaporative coolers. A quick examination shows that, while it can
    stand a good cleaning, inside and out, the only operational problem is a disconnected electrical
    wire inside the case.

    So now I'll have to suffer through the summer with TWO evaporative coolers!


    4 years ago

    It got up to 98 degrees here today (outside in the shade). Inside, it never got out of the 70's. Not bad for $15 -- and five gallons of water!


    4 years ago

    Bruce is correct. That's why DRY are is stressed in the first diagram and on the first page. As mentioned on the last page, I have a small window open on each end of my house. Dry air is sucked in at one end by the fan, and the humid air is blown out the other end by the same fan. It works exactly the same way whether your cooler is inside a window, outside a window, or on the roof. You need to move the air through the house both to get dry air in and get humid air out.


    4 years ago

    The problem is that in dry air these work great, and you can generally get a 20 degree (or more even) drop in temperature on the air in vs. air out AS LONG AS the humidity of the input air is low (preferably less than 30% - the lower the better). But, guess what?... The air coming out of your unit (which just evaporated the water to cool down) is high humidity air. It doesn't take too long to raise the humidity in a room to 50% or 60%, and if you live in the muggy south or east coast, just forget about it. It won't work at all, since your air starts at 60% or more.

    I live in New Mexico (our humidity measured 3% a few days ago!) where they work great!, but we don't use them 'inside' the house. They sit on the roof, drawing in dry air, which is cooled and humidified as it flows through the cooler pads. You open windows all over the house 2 or 3 inches to let the warmer air in the house escape as the (cool, humid) air enters. Since they only cool outside air, they can only get a house maybe 20 degrees cooler than the outside air temperature (perhaps a bit more). It seldom breaks 100 degrees here in Albuquerqe (at 5000+ ft.) so they work quite well. They are much cheaper to operate than refrigerated air.

    They are great units, but you need to understand how an why they work and apply them correctly.