How to fix your swamp cooler ("Overclock" it 50%)

Swamp coolers work ok until it reaches 94 degrees. At that point, they stop cooling as well, because the pump can not get enough water on the pads to keep them wet. So by increasing the amount of water going to the pads by 50% the unit cools the house down faster, and the pads don't dry out.
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Step 1: Replace the blue pads with good old aspen

The blue sponge pads do not really absorb the water very well and do not cool well at all. So pitch them and replace them with the low tech, sustainable aspen pads. the aspen wood actually absorbes water in additon to creating a curtain of water which makes the swamper cool better. It does get messy at the end of the year but it is worth it. These pads are also cheaper.

Step 2: Materials

Picture of Materials
you will need the following: (I purchased everything at Home Depot, but any decent hardware store should stock it) A pump, a supply tube, a distribution array ("spider") a pump basket, a basket filter bag, a grounded 3 prong splitter (not pictured) 7" and 14" zip ties... (10 of each should do) a pair of dykes, a utility knife, a radio or cell phone to have someone turn on and off the pump for you and about 2 gallons of water- to drink while you are cooking on top of the roof because you didn't get started until 1:00 pm in the afternoon.

Step 3: Shut down the power and lock out the power

ok. Go to the power switch and turn off the swamper. Then take some duct tape and tape it off. Then put a little sign that says not to turn on the power. (if someone turns on the fan motor while you are in there you will get hurt.) Also, you can unplug the fan motor up in the swamper for extra safety.
OK.. notice that there are 8 tubes on the distribution assembly, 2 on each side. We are going to add 1 tube to each side taking the total tubes to 12, our 50% overclock.
Dr.Bill3 years ago
(removed by author or community request)
Pwag Dr.Bill9 months ago
The heat from the roof aids in evaporation.

If you put it under ground it'd be cool, but it'd not be an evaporative set up. It'd be something closer to a geothermal exchange, which is ALSO VERY COOL.
turncoat Pwag6 months ago
My cooler is a side vent under a porch facing east, I use the aspen pads on the outside (inside facing out) and the blue sponge pads on the inside right up against the aspen pads. This combo seems to work best and it helps keep out the dust. I also drain and clean the bottom every week to prevent mold. I also installed a new tube overflow drain, the tube comes out easy for draining.
Next year I'm going to cut a round hole and use a bathtub drain plug for faster water draining and install the extra pump and spider for better pad saturation. Last year I installed a 5000 watt solar system and with the new swamp cooler I only use 10% of the electricity I used last year in August!
Pwag turncoat6 months ago
How cool does your place stay with this and how hot does it get where you're at?

turncoat Pwag5 months ago
So far with the two pads I'm good to the high 90s. Here is a chart that will help you more, it's all about humidity...
Just right click highlight, copy and paste in your address window...
Pwag turncoat5 months ago
So in July I read our humidity can drop below 23% and hit 92 degrees.

So...I could put out 74 degree air.

I might have to do this next year. I can't justify central air right now and this might work as well.
turncoat Pwag5 months ago
Yes, I get about a 20-25 degree drop in temp., and I have a big house with a 5000 cubic foot per hour unit. You will find out what you are comfortable with, and you will adjust. Oh and check out the up-duct...
Pwag turncoat5 months ago
Now I have to figure out what an upduct is. Thank you for your help.
Dr.Bill Pwag9 months ago
Never Mind
O-Budd-111 months ago
Living in the southwest US, what I do is use the aspen pads but single layered and then use the largest tubing the spider and pump will accept, but the caveat is you need to remove the smaller connector sections of the spider inlet and pump outlet or you might as well stick with the smaller tubing the manufacturer of the unit put in.

This alone helped improve the cooling on a mobile home in Moab UT even though that summer was hotter than the year before ... even long time residents said it was much hotter (120 in the shade)!
mattlth1 year ago
What a great article! I live in Utah, USA, and it's already been over 100 degrees F on several days this summer. So I started surfing for ways to lower the indoor temperature. After looking at the troughs above my pads, I noticed that they were only filling about halfway. So I assumed I could install another pump and go for a 100% increase in water supply. (The holes in the troughs get progressively larger as the water level rises, too.) Plus, I pulled out the high-tech paper pads and replaced them with aspen pads. (Upon inspecting the paper pads, they were only about 66% wet during a 90 degrees F day and on low cool at the time!) After installing an additional pump and an 8-way spider, the result is a decrease of 7 degrees F. (From 82 to 75.) At 4:00 PM, I inspected the pads and they were totally wet. Mission accomplished! Thanks for taking the time to devise and share an affordable and effective way to increase cooler efficacy.
mbush52 years ago
i have a couple of mastercools oon the roof of my house, they are over sized for the area they are cooling but do a very nice job when needed. my issue is that one of them has stoped turning on. i have taken a look and the cooler in question shares a thermostat connection w/ the ac and there have been contact installed on the cooler. the contact are getting signal from the thermostat as they are engaging but the cooler sits quiet. i am a bot new at these although my dad was always tinkering with our as i grew up. anyone have suggestions on what the next step is??
vatosupreme (author)  mbush52 years ago
Sometimes the relays go bad.
So you could check that. Check to see if the motor is receiving current.
smokeynutz2 years ago
I live in Palm Springs and I have noticed the blue sponge pads work much better than any straw ones. They tend to keep moist longer while after about 2 months the others will just drip down into the reservoir.
solarmatrix4 years ago

Hi all,
I live in Melbourne Australia where we have extremely hot and dry summers and as a result I have done a heap of modification and testing of evaporative coolers or Swamp coolers as you call them. My greatest success came from the use of celdex which is the media commonly found in rooftop home /commercial coolers.
It is a specially treated corrugated cardboard which remains rigid, is highly water absorbent, has much greater surface area than aspen and it doesn’t rot and smell like a swamp. The design and angle of the corrugations/ channels forces the air to foil or roll up and down through the material rather than a straight horizontal flow though creating a much cooler and less restricted and more directed airflow.
 I recommend being careful about airflow restriction as the motor/fan relies on flow for cooling and not all portable coolers have a thermal cut-out. I would not recommend multiple layers of aspen for that reason. Celdex is easy to cut to fit and is somewhat self cleaning in operation.
Filtration of the water going through the pump and spider is recommended because evaps filter a lot of dust from the air which ends up in the water reservoir and blocking spreader/spider holes. Flywire or fairly fine mesh around the pump does ok.
Bigger or more pumps will help to a point but the main key is the surface area of the media. I get superb performance from my coolers after mods but the only downfall is they use at least twice as much water. But this goes to prove that I am getting at least twice the performance from them as the more you evaporate the more you are cooling. A friend was seriously fooled into thinking they were a refrigerated air conditioners! I think they need float valves connected to the garden hose as I got sick of trying to keeping them topped up. I also experimented with a solar powered evap cooler made by fitting a small cooler with an auto thermo fan and 12 volt bilge pump from a boat running from 80 watt solar panel. One final note is to the importance of both ventilating the moist air from the opposite side of the room from the cooler and providing the back of the cooler with fresh dry air from outside. This helps keep internal humidity down so your sweat can also evaporate. Hope this is a help for all to stay as cool as I and use little or no power to do so.

This is exactly what I tell My wife: "you have to open the windows for it to work dear"!! I just installed the Low Profile "DURANGO" cooler from BONAIRE.
I live here in Las Vegas Nevada, And this is the first time I've ever seen this type of media. The celdex is very efficient, wets completely, and allows for good air-flow even when salts are built-up. There was the added boon of cutting a 23x23" hole in the wall to install it, as I chose not to mount it in the windo!!!! RRRRRRR!!
Hi, I also live in Melbourne, and we also have a "Swamp cooler" Ours is a fairly recent model, with some handy features. The first, is if the cooler is left for 72 hours, it automatically drains the water, so it's never stagnant. The second is a float valve, so we never have to worry about the water levels. I believe it has paper pads, as we have never had to replace them.
Your friend is overlooking the savings you will achieve at lower temperatures by being able to run the cooler at a lower fan setting. Excellent 'Ible, as I wonder: Hmmm, May-be I can Boost mine!!
ramjet2 years ago
My previous house had a swamp cooler, and I was always looking for ways to improve performance. My best idea was to merely shade the unit. I used a piece of plywood larger than the surface area of the unit and placed it on standoffs on top of the unit. On my current house which we had built, I had the coolers installed on the ground (one at each end of the house) to allow for easier maintenance. They also were in the shade more.
colty772 years ago
You can build a very cheap primitive one of these. A medium large fan with a tub of water placed behind it. The tub is placed on something so that it's top is almost level with the top of the fan. Drape a wetted towel over the edge of the tub... one side of the towel is soaking in the water. The towel will wick the water over the edge of the tub as long as there is sufficient water in the tub.. have a tub also below the towel to collect the dripping water. The fan will draw air over the wet towel, cooling the air.
Cheiron2 years ago
Tinker234: A swamp cooler is a saturated mat of water that has air blown through it by a fan, a pump keeps the mat wet. In this case the mat is woven Aspen. The purpose is to be a cheaper and easier to maintain way to cool your house. I've read they work particularly well in arid climates.

Very nice instructable.
tinker2342 years ago
what is a swamp cooleer more importenly can it cool you down for cheap
use an outdoor thermostat(placed on the afternoon shady side of the cooleraway from any hot metal or asphalt shingles for greater accuracy) set to 95 degrees so that the power to the first pump would be on when switched and the 2nd pump would be on ONLY when main pump is switched AND the outside temp is 95+degrees. and to my previous comment of using mister sprayers you can build a PVC setup(a PVC cube that uses the cooler to hold it up?) to have 2+ levels of sprayers and to point the sprayers directly at the pads for more compete coverage of water on the pads(my cooler uses "green" pads so the water absorbsion is not as good but i have ALOT LESS chance of getting that musty/moldy/mildew smell. maybee i could do some drawings to better express my idea. shoot me a message if your intrested in taking this further
i am wanting to do this mod to my cooler(im a renter so it may not be feasible) but using the ecopump(shaft driven pump) as the secondary pump. the idea i had was to add a water mister system to the outside of the cooler. have 1-2 on top(spraying down) and the same on bottom (spraying up) on each side to pre-cool the air entering the cooler. this may only be usable on days with low wind or when the cooler is on high setting to have more pull for getting the air into the cooler thus pulling in the chilled misted water .my only worry would be the calcium clogging the system so i would highly recommend getting the in-line carbon filter available for these water mister systems. i have nearly no knowledge of swamp coolers as i am from the east coast but would alot of ice(or dry ice) placed in the cooler do any good by chilling the water to be pumped onto the pads?
Jawatech6 years ago
These things don't work very well. We put one in our shop to try it out and all it did was make everything smell like the Pirates of the Caribbean ride at Disney. A Large Shop Fan works way better.
If it smells, then you probably have algae or something growing in the cooler. And not having somewhere for the air to go also doesn't help. Unlike AC, a swamp cooler needs a few doors and windows open for it to be effective. Also, some climates aren't suitable for swamp coolers due to high humidity.
yeah these are designed for and work wonders in dry areas.
Omg I love that smell! I went as far as bottling some while on the ride! But now I can make my own Pirate of the Caribbean ride smell!
It is Extremely Humid here in Texas, Usually like 90-100% humidity. so that was probably the reason.
there is ALOT of good ideas here like swapping to a 12 tube spider(or even using 2 spiders..24 tube spider hmmm =:-P ). i didn't know about the ecopump and want to try it out for the 2nd spider. my thought train may sound like overkill but i thought about swapping to the 12 tube spider with a 95 degree thermo switch (to save power via cutting the electrical pump at higher temps) and then adding another 8 or 12 tube spider with the ecopump. but I'm surprised no one has mentioned a new technology called Coolerado uses 90% less energy than an A/C unit. the smallest one for a 1500sqft house can not only be powered by only 450watt of solar cells, it cools any other solar cells you might have to make them make efficient and cools the indoor air without adding or removing humidity to he inside of your house. would have a decent payback time of under 10 years for those of us in the dry desert climate(longer for more humid areas but works well in somewhat humid areas as well
jpatramirez3 years ago
I assumed others had great ideas...glad I checked this. I'm not as "handy" and not sure if I'll try this, but I'd throw these 2 ideas out: **what about painting the entire outside of the unit/box white? Mine is a cream color and I can only assume that by retracting light, I may also retract some heat. **years ago, I remember a commercial on local TV about a "cover" for the cooler...which was essentially a fitted styrofoam box (like those coolers at convenience stores). The idea was to keep the box cooler. There were holes on the sides of this to allow air flow. I have the blue pads and will probably replace them. I got up on the roof just now (Its 103 on the ground!) and was washing off the bird poop. My wife and I noticed that when I came down it was cooler. I wonder if just cooling the box like you mentioned with some water sprinkler could work. Great ideas. Thanks!
Theres a lot of good ideas here thanks. Ive researched a non electric pump called the eco pump it uses the spindle of the fan drum to power the pump its actually is a really good idea to double the flow of water i think the link is or check it on you tube. But iam really thinking of getting a 8 spider instead of the 6 that i have running on my window swamp cooler so i have 3 outs on two sides and the normal 2 on one but experimenting with doubling two sides on 3 outs and 2 outs on one or maybe reversing so there is not too much restricted air on the doubled pads
coldbear4 years ago
Aspen is not necessarily the best choice. Lived in Barstow CA for over a decade (think Death Valley). Aspen is better at the absorption than the blue but degrades more quickly and if you have a hard water supply it will cause it to clog really fast. The overall best choice for pads is paper, but that is becoming hard to find. Doesn't have the margin of the blue, nor the traditional appeal of Aspen. Aspen is also right out for those (like me) with tree allergies. Whatever pads you use, change that at least once a season. If in a desert area probably when you first use it around mid April and again around the Fourth of July. Shade for the cooler itself is also a big help.
Ed Jones4 years ago
There is a hotel in 29 Palms that uses Evaporative cooler only. This makes them very environmentally friendly. Check them out at
robhybrid4 years ago
You want to switch the second pump based on outside air temperature. The swamp cooler is already outside. Just wire the second pump through a thermostat switch on the outside of the housing that will close when the outside air temp rises above 95º F. Problem solved.
bgraham1117 years ago
Swamp coolers cool by absorbing heat energy. How do they do that? Phase change! Energy is required to turn liquid water into gas (evaporation) and that energy comes from the hot air. Way more energy efficient than AC. However, if the air is already full of water gas (high humidity), it doesn't work so well. You're body uses swamp cooling - it's called sweat. It's also why sweat doesn't work in high humidity but works great in a dry heat. Living in Michigan, I had never heard of these until I took a hot weather test trip in Yuma Arizona in July.... really cool units. (Of course, there is the issue of getting lots on water in the middle of Arizona..., a problem we don't have in Michigan.)
Someone earlier suggested that putting ice in the unit would help. Would it help?
Good explanation. Georgia generally has high humidity and I've still seen them around here. I think even with high humidity, they will still work with high airflow (a big fan). Probably venturi effect reducing air pressure and causing a lower evaporation point. Probably not quite as efficient/effective, but it does still work.
desertguy4 years ago
Hello. What a wonderful ideal about the "overclock"! Instead of adding another spider/lines and adding another water pump, there are spiders available with 4, 8 and 12 holes/tubes. When replacing my spider this year I accidentally came home with a 12 hole spider and returned to Home Depot to replace it with my original 8 hole. Now, after reading your great idea I wish I had kept the 12 hole. I wonder if I can continue to use the same water pump if I go back and get the 12 hole. Would I need a stonger water pump? Also, I'm not happy with the cooling of my evaporative cooler and I've been using the blue plastic pads. They're easier to clean the cooler and cooler screens but if using the aspen pads would work better, the little work of cleaning would be worth it. Can I double up the aspen pads? Please advise and thanks, DesertGuy
vatosupreme (author)  desertguy4 years ago
I'm not sure.. I think more holes would be much easier however... I think this is all based on the flow rate of the pump.... So if you could get a bigger pump, then I think this would be an easy upgrade. However, after using it for a while I would definately like the temp switch, because I noticed the house got a little too humid and a couple of my doors swelled up and I had to sand them a bit... As to the Pads, Aspen is way way better... I think to double the pads you may have to modify the pad holders but I'm not sure. I would do a test to see if your pads remain wet for 2 hours in hot weather. If they stay wet, then I would say that you would not need to dble up. On the divider, I just tried to center it as best as I could

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