Lots of folks talk about em, but have lived with them for nearly 40 years now.
Anyone have neat tricks to add, tack em on please.
The key to evaporative coolers, is evaporation. This means you have to raise water to the state where it goes to a gas. Sublimation from ice to air is most desirable, but not going to happen often it the south where we have these, and is even harder to spell. But if you want to:
The enthalpy of sublimation (also called heat of sublimation) can be calculated as the enthalpy of fusion plus the enthalpy of vaporization.
Lets just stick with water in the liquid phase then.
To really make a swamper work well, you want to try to get the cooler pads to be DRY at the bottom 1/4 inch on the outside. This means that all the water is evaporating before it gets to the bottom of the pad.
The point of that is that this is the most efficient tuning you can get, and keeps the water that is dripping off the pads from cooling the reservoir water, hence making it harder to evaporate once it goes back up to the distribution system, or the "spider". There is usually more than one, but we mean the black plastic thingy with arms, not the black chitinous one with the arms and hourglass on it.
In the old days, we just had a "once thru" system, with water going directly to the spider, from standard plumbing pressure, and you could adjust the flow to get it just where you wanted it, less water on humid days, more on dry days. This was way to simple and effective, so we have now added expensive and phiniky floats, pumps, flow reducers, extra hoses, and fittings to leak.
This makes it MUCH harder to get just the right amount of water up top, but makes it take zero time most days, and half a day a couple times a year to keep it functioning.
The key point here, is to buy the LOWEST flow pump you can find. They tend to take the least current draw too, so helps offset the insane price for a small, breakable, plastic housed, inefficient pump.
This is still way too much flow, so while you are at the hardware store, pick up a 1/2 flex armored wire stress reducing coupling for electrical box connection. I know, I know, just look for the box connector for armored cable that has the big nut on one side, and the 2 screws pushing down a clamp on the other. You want this style so you can put it around the pump to spider hose without having to touch that cheesy plastic pump outlet.
Put it on the hose where it wont be dripped on, and that you can get a screwdriver to adjust it easily. Crank it all the way down. This is still not going to be enough, you are prob going to still need to shim it a bit, but start there. What you want is the lowest amount of water, that still feeds all the spider arms nearly evenly.
If you consistently getting feed problems at one or two arms. get the teflon tape out , and unscrew the attachment nut. You noticed which way it was pointing from the hose up, right ?
Clean out the junction with an old tight wound spring, or old wound guitar string, bass or low E is best.
Now wrap the junction feed screw with enough teflon tape to get the hose feed to come in from the north facing pad side. You want the lowest pressure on the north side, because it doesn't get direct sun, and will be the least efficient at evaporation.
Ideally, they would make a three sided down draft, for the roof, but no such thinking has ever gone into swamp cooling, cuz there is beer to be consumed. (see the History of Swamp Coolers)
As such, don't put a side draft, or window cooler on the north side of the house, you always want the air intake to pull the hottest air you can find easily.
One of the old Arizona cooler manufacturers used to build an upgrade kit that consisted of a wedge shaped piece of sheet metal that would draw air off the roof surface, for the hottest air. It was painted dark brown too. They could never convince folks to try them , so finally quit making them, but everyone wants to make their coolers to work better, and nobody listens to non-intuitive approaches.
Ok, back to the roof.
You have the water flow nailed, but there is another factor lurking up there by the spiders, (plural , this time) and that is leveling.
Ideally, when whoever installed this cooler, wasn't drinking beer, and has had their own cooler for many years, and know how critical leveling is with low water flow.
Old time coolers actually had leveling screws built onto the distribution trays on the top, inside of the cooler pads. This is irrelevant now, because even if you have one of these old coolers, the screws are welded with rust from being around all that water vapor, not to mention galvanic response, and those dang spiders hiding under there.
Some of the newest plastic coolers have fairly adjustable leveling legs, and some of the older standoff metal coolers had them too. If so, go down the ladder, and get the Aerokroil , and another beer, cuz even if you spray em right now, they aren't going to loosen for another day anyway.
If no leveling options are available, you can try and switch locations for the pads from one side to another, and try and guess. Usually this consists of whipping the top of the pad open, and looking at the water level. Since you are trying to move the pad open quickly, this doesn't work that great. Better move is to remember that when you buy your own mini-level for pictures and shelves, is to get the one with magnets built into the side. Then you can reach in from the far side, attach it to the trough with the magnet side, and look at it from across the cooler. Don't bother with this step yet if you have to level the entire cooler.
The last problem with the troughs, is the drip openings. After changing pads, and especially after cleaning the spider , the little chunks will plug up the drip slots. I like to clean out the edge ones with a sharp knife, but tend to leave the ones right under the spider outlets loaded up at least halfway, so as to force the water to the perimeter. That is where the most shrinkage occurs on the pads, so keep an eye on it.
Leveling the entire cooler. Good luck with that. And you did borrow that 4 ft. masonry level from the neighbor you always return tools too, right ?
This is really tough without 3 people up there, and 3 guys, on the roof, with beer, is well, on the news at 5.
Ok, lets say you got it, and it is working fab. Now whip out that handy dandy Sharpie, and draw marks right over the junction between the top of the pad, and the main cooler body at top.
I like to use a triangle, circle, square, and an upside down triangle, because the halves look very different laying on the rooftop after changing pads, when you are drinking beer. But feel free to use numbers, lines, or pentagrams on all sides that you feel artistically inclined too. Remember you have to match up halves of the patterns tho...
Changing pads is the Zen of cooler repair. Simple, straightforward, and mind numbingly easy to forget the size. Write it on the outside where you can see it with binoculars from the ground. And on the on/off water valve, and inside the closet, and.... Silver sharpies work great for marking on plumbing parts by the way. Unless you use spray teflon on all your plumbing fittings, which you do anyway, right?
Pads should be changed every year, and if you live in monsoon country, change em when the monsoons come. You want maximum efficiency for the humid season especially. I have had the best luck with aspen pads, but also adding a 4" strip of the blue synthetic right at the top, touching the trough. Seems to spread out the water better than the aspen at the top, and seals off air leaks up there.
The opposite tack can also be used. I call this the Toyota Oil Change method, since i know many guys that only changed the oil in their 22r's every three years or so.
This method rely's on the growth of the salt crystals to use as surface area, rather than the wood or synthetic pad material. Works just ok, and leaves more time for drinking beer, especially if you don't want to use the water change method, (or oil change for that matter) we will get to next. The time interval here is when you actually push thru one of the pads on accident, or they simply start decomposing on the edges and bottom as a freak change of PH in the hard water dissolves the material. Or you have lots of birds.
If you want your pads to last, and be efficient as possible, then you are going to have to add another complex system to the inherently overly complex system that already exists.
Remember that old 'once thru" system we talked about up top? There we had the water entering at the top of the system, and flowing down the pads, and out. This flushed out extra salts, kept the water low in the pan, because you don't have to have a overflow tube, and cut down on cooler body rust, because of said low levels of water in the pan itself. And removed a whole magnitude of complexity too!
You do have to move the hose around everyday, but you can do that with one hand still on your beer coolie, and the grass needs watering anyway. And you might as well dilute the uric acid and beer a little more anyway....
Sadly, with water bills surpassing electric bills in homes with swampers in the summer, it kinda grates on the nerves to be paying for that water. So we will just reuse it !
The other major drawback with the recirculation system of swamp cooling, is the increase in alkalization not only affects the pads, the cooler body (just add another piece, the magnesium rod for sacrificial
duty), that rots away quicker under the assault of PH, and the cost and cantankerousness of the whole pump, float and overflow system. There are some bypass fittings available in the older hardware stores that bleed off a portion of the water getting pushed thru the pump, ( called bleed-off fittings for lack of a better term), but you still have to remember to move the hose every night when you go out to use YOUR beer bleed off fitting.
Fortunately, someone in a semblance of temperance, realized that they could make a financial windfall, and save the lives of many of the discarded cooler carcasses littering the desert out here, by making a timer pump that bleeds/pumps all the water out of the pan on a daily basis. This is not just brazen capitalism at work here. By flushing the water out, you are also getting a little closer to the ph where water evaporates more efficiently, and saving the said carcasses at the same time. The drawback to this fabulous solution is the dang timer pump now costs 75 bucks ! This severely cuts into the beer procurement funding, so lets make it more complex, to SAVE money!
My favorite suds saving tactic is to go to the extension cord aisle, and pick up an outdoor timer, (that is not an Xmas light timer. Is dark in that cooler, thats why the spiders like it !) with a 3 prong outlet and sorta weather resistant. Also pick up a 3 way plug splitter. Then head on back over to the cooler department and pick up ANOTHER water pump. This still hurts in the coin department, but seems like a good tradeoff with not having to change the pads at monsoon time (20 bucks at the peak of beer hunting season, and that when you don't want to be anywhere near a roof in Arizona).
Crawl back up the ladder again, and take a self tapping metal screw or two with you this time, and the electric drill. Got an old piece of double backed foam from the xmas timer you opened before you took it back, take that up with you too. Helps hold the real timer in place.
Find a spot on the squirrel cage housing that is pretty high up, and pretty solid - stay away from the lower middle section, it vibrates a LOT. Sometimes the vibration is caused by a too long self tapping screw that is hitting the squirrel in the cage, but that is another long story...
Mark out the spacing for the timer mounts, and drill in a couple screws to fit the back. Lock it down with the double sided foam tape.
Now plug the 3 way splitter in at the main plug, hook the regular pump to one outlet, and the timer to another. Plug the second pump into the timer, and make sure the wire to the pump loops down LOWER than the top of the pump housing. You don't want to feed water to the pump down the plug wire. Water for pumps comes ups !
Set the timer to come on about dark, 8:30 or so out here, you still want to be able to find the hose when you hear it start to pump out the water, or how are you supposed to remember to move the dang hose around?
For serious bonus points, also set the timer for your coffee time period in the morning. This allows you to maybe remember to move the hose before your beer bleed off outlet fitting reminds you in the dark, and also keeps the water from getting so alkalai that it is not of much use except under the pines or on the crabgrass, which is the only thing that grows on these caliche wastelands.
This has been a public service announcement / warning from your local water company, the brewery, and the chiropractor listed inside the cover of the phone book, for all you idiots drinking on the roof.
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If your water flow is not strong enough, you can get dry holes in your pads and suck in hot air. I switched to an Adobe Air model with thick honeycombed paper pad. They are now out of business. It is a shame because their thick-pad coolers worked great. I think that there is a source for replacement pads, but I don't know if they are refreshing their inventory.
Insulate all metal surfaces, other than the grill panels, but including ductwork, as they can transfer a lot of hot air into the system. I believe there is, or was, a product called the Snow Cap, or something similar sounding, sold in New Mexico. It was the same material used with water heater blankets. It was designed to cover the top of a downdraft roof mounted cooler.
I bought an inexpensive siphon-based drainer several years ago, but have never installed it because the Adobe Air system uses a different distribution setup and the pump has a bleed hose. I have read that draining the pan daily is more effective than a bleed system, and uses far less water. The siphon system only requires that you turn off the pump for about fifteen minutes a day. Because water is so expensive now, I plan on finding a way to install the siphon drainer and plug the bleeder hose.
You need to "tune" your house correctly to get the most out of your cooler. You need to let out as much air as you blow in and it is best if you set it up so the cooler blower is pushing hot air out of the house. I have my cooler installed in a basement window and I keep the attic access door open to let the hot humid air out. I also keep all the windows in the house open a little bit to encourage the cool air to circulate into each room. All interior room doors should remain open at least 4"-6". Some of the kids choose stifling heat rather than marginal loss of privacy. If it starts to get "swampy" you need to open the windows wider.
I added another floor to the house a few years ago which doubled the floorspace, but the cooler will still cool the entire house, though I need to use some strategically placed fans to help move the air upstairs and down the hall.
When the humidity rises above 50%, we go to the dollar movies.
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