Evap vs Air Conditioning

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Re: Evap vs Air Conditioning

Postby BurnerBunny » Sat Feb 16, 2013 9:34 am

I'm doing the basic 4' high layout, then adding 2' on the bottom to make it taller (hopefully no crazy winds this year, I hear that modification isn't very well tested). It is 166 square feet.

I'd have the transfer switch installed, but crap I forgot some of the appliances I'm trying to power might be 240. The big two are the fridge and the furnace. The furnace is gas, but I think it needs electricity to operate the fans so I'm hoping it's not 240.

shit, now I need to consult with an electrician prior to dumping a grand into a genny. Might end up with a swamp cooler running off a marine battery after all. I hope I get the go ahead to buy the honda <crosses fingers!>

Captain Goddammit wrote:How big is your hexayurt? You may find an 8000 BTU A/C inadequate. I have a similar window A/C as a backup in my truck camper in case the roof A/C fails, and I've found it can't really cool the thing.

Another thing I noticed you're overlooking: A/C units need a lot more current to start up than the rated running power usage. A Honda EU2000 will most likely handle the small A/C you're looking at but might not start up the bigger unit I think you might need.

You mentioned setting up your house with a transfer switch to use the Honda at home... you can do that, you just need to make sure it gets set up right because most transfer switches are made for use with generators that produce two-phase 240VAC power and the Honda EU2000 only makes single-phase 120VAC.

Oh, and the cheap Champion generator... the decibel scale isn't linear; 5 dB is a lot louder, generally to a human its a perceived increase of about 50%, about one and a half times as loud. The difference between say 59 dB and 64 dB is a bunch more than the numbers would seem to indicate.
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Re: Evap vs Air Conditioning

Postby Rice » Sat Feb 16, 2013 10:15 am

BurnerBunny wrote:I'm doing the basic 4' high layout, then adding 2' on the bottom to make it taller (hopefully no crazy winds this year, I hear that modification isn't very well tested). It is 166 square feet.

I'd have the transfer switch installed, but crap I forgot some of the appliances I'm trying to power might be 240. The big two are the fridge and the furnace. The furnace is gas, but I think it needs electricity to operate the fans so I'm hoping it's not 240.

shit, now I need to consult with an electrician prior to dumping a grand into a genny. Might end up with a swamp cooler running off a marine battery after all. I hope I get the go ahead to buy the honda <crosses fingers!>

Captain Goddammit wrote:How big is your hexayurt? You may find an 8000 BTU A/C inadequate. I have a similar window A/C as a backup in my truck camper in case the roof A/C fails, and I've found it can't really cool the thing.

Another thing I noticed you're overlooking: A/C units need a lot more current to start up than the rated running power usage. A Honda EU2000 will most likely handle the small A/C you're looking at but might not start up the bigger unit I think you might need.

You mentioned setting up your house with a transfer switch to use the Honda at home... you can do that, you just need to make sure it gets set up right because most transfer switches are made for use with generators that produce two-phase 240VAC power and the Honda EU2000 only makes single-phase 120VAC.

Oh, and the cheap Champion generator... the decibel scale isn't linear; 5 dB is a lot louder, generally to a human its a perceived increase of about 50%, about one and a half times as loud. The difference between say 59 dB and 64 dB is a bunch more than the numbers would seem to indicate.

In the Burning Man scheme of things - a swamp cooler is easy and cheap...

For you house, a backup generator is always a good plan. My folks live in northern Canada and they have one for the twice a month power failures that seem to go with the summer storms they get. They have their house rigged so that they flick a couple breakers, plug their big generator in and fire it up... I am pretty sure it is only 110 power (I would have to check). It seems to run everything they need (there is a fire place if the power fails in the winter - forced air furnaces need power to work). Once you get your place rigged - a generator is awesome :)

Oh, to keep the volume down on your generator - just build a box for it. (ensuring a large vent hole near the exhaust and another one on the other side for air intake.) We found that our baffle box reduced the noise by 50% and you could hardly hear it from 15 feet away. . .
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Re: Evap vs Air Conditioning

Postby Captain Goddammit » Sat Feb 16, 2013 12:04 pm

Rice wrote: They have their house rigged so that they flick a couple breakers, plug their big generator in and fire it up... I am pretty sure it is only 110 power (I would have to check). It seems to run everything they need (there is a fire place if the power fails in the winter - forced air furnaces need power to work). Once you get your place rigged - a generator is awesome :)


The 110/120 volt power in a house is actually one side of 220/240 volt two-phase power, which has a neutral wire and two "hot" wires. From neutral to either hot measures 120 volts, and from one hot across to the other hot is 240 volts.
About half of the house will be wired to one phase of the incoming 240 volt supply, and about half will be wired to the other phase.

The Honda only makes single-phase power but if you set up the wiring right it can run the house. I'm just mentioning that because almost all the available home generator transfer switches are designed to be fed two-phase 240 volt AC from the generator. You can probably just tie both "hot" sides together in the transfer switch but it has to be done so that ONLY happens when completely isolated from the normal power or there will be sparks.
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Re: Evap vs Air Conditioning

Postby BurnerBunny » Sat Feb 16, 2013 12:18 pm

I was thinking about buying the honda eu2000i companion too, sounds like if I have 2 then I can hook them both up?
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Re: Evap vs Air Conditioning

Postby Rice » Sat Feb 16, 2013 1:04 pm

Captain Goddammit wrote:
Rice wrote: They have their house rigged so that they flick a couple breakers, plug their big generator in and fire it up... I am pretty sure it is only 110 power (I would have to check). It seems to run everything they need (there is a fire place if the power fails in the winter - forced air furnaces need power to work). Once you get your place rigged - a generator is awesome :)


The 110/120 volt power in a house is actually one side of 220/240 volt two-phase power, which has a neutral wire and two "hot" wires. From neutral to either hot measures 120 volts, and from one hot across to the other hot is 240 volts.
About half of the house will be wired to one phase of the incoming 240 volt supply, and about half will be wired to the other phase.

The Honda only makes single-phase power but if you set up the wiring right it can run the house. I'm just mentioning that because almost all the available home generator transfer switches are designed to be fed two-phase 240 volt AC from the generator. You can probably just tie both "hot" sides together in the transfer switch but it has to be done so that ONLY happens when completely isolated from the normal power or there will be sparks.

My folks have to kill power from the Mains, before they hook up the generator... Easy peazy :shock:
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Re: Evap vs Air Conditioning

Postby gyre » Sat Feb 16, 2013 1:31 pm

Yes, 5 db is a honking difference, but db isn't the most important part.
The spectrum of noise is far more important, nvh = noise/vibration/harshness.

I've been in a village with lots of tents cooled by small ac units, and they seemed to work okay, but we had a power grid.
Evaporative seems a better approach to me.
I've poured water all over the tent to get temporary cooling out there.
Shade is critical.
With enough shade I was cool enough to noon.
Most shade is inadequate.

I like the hexayurts, but many don't seem to have a shade structure or attic.
Insulation will not replace blocking the heat in the first place.
The radiant reflection will make a big difference, but from comments, it isn't enough.
I've seen cardboard and plywood box houses out there with a four inch air gap attic that stay cool.
Perhaps a little shade and a small wet cooler is the better approach?
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Re: Evap vs Air Conditioning

Postby Captain Goddammit » Sun Feb 17, 2013 3:54 pm

BurnerBunny wrote:I was thinking about buying the honda eu2000i companion too, sounds like if I have 2 then I can hook them both up?


Yes, you can, that's one of the coolest things about them - but you don't need the so-called "companion" model, or Honda's overpriced "parallel operation cables".
I like to use two 12-guage cords sold as "power tool replacement cords" that already have the male plug molded on, and run them both into an outlet box (just a cheap, ordinary home outlet box like you'll find at Home Depot) and screw both cords onto whatever style outlets I need. For me that's a 30-amp standard "RV" outlet, but you could put regular household style outlets on your box too.

Or simply cut the female end off a short extension cord (use a nice heavy 12 gauge one) and put a male plug on, so it has a male at both ends. Plug this into each Honda and you're in business.

Two sort of obvious but worth mentioning cautions: An extension cord with live exposed prongs is potentially dangerous (hey this IS Burning Man) so don't leave it lying around plugged it at one end with the other end dangling into a baby carriage...
Second, plug both generators together FIRST, THEN start them up. You can start and stop either one or both as you please while they are connected. Just don't connect them while the motors are already running.

My experience/testing/screwing around has shown that even different size Honda EUs play well together, I've connected EU1000, EU2000, and EU3000 sets together and they all seem happy.
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Re: Evap vs Air Conditioning

Postby Token » Sun Feb 17, 2013 4:55 pm

Captain Goddammit wrote:
Rice wrote: They have their house rigged so that they flick a couple breakers, plug their big generator in and fire it up... I am pretty sure it is only 110 power (I would have to check). It seems to run everything they need (there is a fire place if the power fails in the winter - forced air furnaces need power to work). Once you get your place rigged - a generator is awesome :)


The 110/120 volt power in a house is actually one side of 220/240 volt two-phase power, which has a neutral wire and two "hot" wires. From neutral to either hot measures 120 volts, and from one hot across to the other hot is 240 volts.
About half of the house will be wired to one phase of the incoming 240 volt supply, and about half will be wired to the other phase.

The Honda only makes single-phase power but if you set up the wiring right it can run the house. I'm just mentioning that because almost all the available home generator transfer switches are designed to be fed two-phase 240 volt AC from the generator. You can probably just tie both "hot" sides together in the transfer switch but it has to be done so that ONLY happens when completely isolated from the normal power or there will be sparks.


And to add to all this phase crap, the Honda EU2000i dissent even produce 110V AC. It runs two 55V rails to both Line and Neutal. The net effect is 110V.

That's how they get away with the "no circuit braker" design. 55V is less than lethal.

The portable low-noise Honda's are a rather poor choice for home power.
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Re: Evap vs Air Conditioning

Postby BurnerBunny » Sun Feb 17, 2013 7:33 pm

hmmm, now I have a lot more to consider. This thread has been very enlightening, thanks again for everyone's input!

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Re: Evap vs Air Conditioning

Postby gyre » Sun Feb 17, 2013 9:00 pm

On the decibel scale, the numbers were transposed in one explanation.
Five decibels is 2.67 times the lower measure, but on a logarithmic measurement, has the perceived increase of five "notches" or decibels, all things being equal, which they usually aren't.

Consider the lowing of a large diesel generator at a steady 500 rpm, compared to an erratic sheet metal model with resonances and buzzes.
They could be similar in decibel levels, but not comfort.
Erratic sounds can be far harsher, often in measurable ways.
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Re: Evap vs Air Conditioning

Postby GreyCoyote » Mon Feb 18, 2013 6:14 pm

Token wrote:And to add to all this phase crap, the Honda EU2000i dissent even produce 110V AC. .


Yes, it does. The nominal rated output is 120 VAC. Measured values between no-load and full nameplate load are very closely clustered around this nominal value. You may be thinking about the old 650, which was known for undervoltage issues.

Token wrote:It runs two 55V rails to both Line and Neutal.


There is no "55 volt rail" anywhere in the inverter output section.

The inverter section is what Honda calls the "electronics module". It is about 2 inches thick and completely potted with hard plastic. It is powered by a 3-phase alternator (delta-wound) that produces about 250 volts peak/peak at no load, and 180 volts fully loaded (I measured). Using the "top" sticker as a reference, alternator output goes in via the large 6-pin connector underneath. Inverter output comes out by the inductor in the upper left of the module. No load voltage is about 128 to 130VAC, with full load being 117 to 120VAC. Frequency is fixed at 60.05 hz by an internal timing reference, apparently a PLL circuit, as the inverter, when paralleled, will automatically match phase and frequency with others in the chain within a narrow range.

BTW: Does that 180 volt value look familiar? That is 1.404 times the voltage of a 125 volt RMS sine wave, minus a couple of semiconductor junction drops.

You are possibly confusing your "55 volt rail" with the floating neutral design used by most portable generators. This design is common and complies with 2011 NFPA 70, Art. 250.34(A). If you have a generator sitting on the bench with a token load, and you tried to attach a meter to the output, you could (wrongly) come to the conclusion there were two 55 rails referenced to ground. An o-scope in capable hands would debunk those thoughts however.

Token wrote:The net effect is 110V


The net effect is a nominal output of 120VAC, exactly as shown on the nameplate.

Token wrote:That's how they get away with the "no circuit braker" design.


A breaker has nothing to do with direct lethality or protection of humans from electrical shock. Most electrocutions at these voltage levels happen with less than 1 amp of current. Breakers are a requirement of the NEC/NFPA 70 and have to do only with fire protection issues under overload or short-circuit conditions. Not coincidently, NFPA = National Fire Protection Assn, are the guys who wrote the model codes adopted by most jurisdictions in the US.

In truth there is absolutely no NFPA or UL requirement for a circuit breaker on a portable generator as long as the output is "inherently self-limiting under all operating and short-circuit conditions". Older copper-wound/non-inverter generators could source considerably more current than the nameplate values during a short, so breakers were required. In contrast the inverter design used on the Honda EU2000i is electronic, classified as inherently self-limiting, and is UL tested as same. There is no possibility of this design sustaining a short-circuit current above the rated output for more than a brief second or two. Under fault conditions the waveform collapses, the inverter faults, and the output is disconnected. (The EU3000i design goes a step further and internally crowbars the output during the initiation of the disconnect event). Such designs do not require, and do not benefit from, a breaker.

Note that later units in the "I" series that have the paralleling option DO have a fuse in the output leg to the front-panel receptacle. See here: http://m.powerequipment.honda.com/pdf/m ... Z07610.pdf Again, the reason is overload current. The receptacle is rated for 20 amps, and in parallel operation it would be possible to draw about 32 amps from that single outlet. Hence the 20 amp fuse. But the paralleling leads provide full, un-fused output at all times.

As an aside, these units can be paralleled beyond just the advertised limit of two. We paralleled four of them just to prove it could be done. That is 64 amps of rated output, and it would be possible for an uninformed user to attempt to draw it all from one receptacle. Again, the 20 amp fuse becomes a requirement.

Token wrote:55V is less than lethal.


Less than 20 volts can be lethal under the right conditions. There is quite a body of literature on this subject.

You appear to consider 55V as "low voltage" and therefore the basis for a lack of a fuse/breaker. This is not true. As far as the code goes, the 2011 NFPA generally only recognizes circuits of 49 volts AC or less as a "low-voltage" circuit. 2011 NFPA 250.20(A)1-4. But see also 2011 NFPA 110.26(A)(1)(b) which defines "Low Voltage" as "...not greater than 30 volts RMS, 42 volts peak, or 60 volts DC..."

Token wrote:The portable low-noise Honda's are a rather poor choice for home power.


Perhaps, but every other generator sold as a local-stock item by Home Depot, Lowes, Cabellas, etc is subject to the same limitations. All are compromise solutions. None of them are rated for "home power" duty, including the "big" 20KW units with a "whole house" transfer switch. Even these are only standby-rated. In most US jurisdictions if you want to power a home routinely and comply with code, you will need a "prime-rated" generator. In the 80KW and lower ranks, these will generally be 1800 RPM diesels with a 4-pole head, with a few high-end prime-rated sets powered by natural gas completing the mix. The only question for a non-prime-rated genset owner is "just how much of a compromise am I willing to tolerate". For some, a little 2K Honda EU2000i will do well enough in an outage. Others will need more.

On the playa, these generators do very well. We have used them since 2007. If you can elevate them 2-3 feet, get them out of the direct line of dust-laden wind, give them an oil change every 50 hours, use synthetic oil, and give just basic care, they don't mind the playa at all. Neighbors will appreciate them for their almost undetectable (at BM) noise level.
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Re: Evap vs Air Conditioning

Postby BurnerBunny » Mon Feb 18, 2013 8:10 pm

fantastic info GreyCoyote, we all just got learned some :)
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Re: Evap vs Air Conditioning

Postby Elliot » Mon Feb 18, 2013 9:51 pm

:D
I second that notion.
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Re: Evap vs Air Conditioning

Postby Captain Goddammit » Tue Feb 19, 2013 11:27 pm

Just an extra note - I use two Honda EU2000s in parallel to power my home during power outages quite successfully.

BurnerBunny, I highly recommend these fantastic sets. You can buy one now and add another later if you want more power.
I choose to own two EU2000s instead of an EU3000; the total cost is about the same, but the pair of 2000s make more power and still weigh less. You only have to handle one 50-pound set at a time instead of a 140 pound unit.

The best thing ever for playa use of a Honda EU2000 is the external fuel tank trick. Three crummy things happen regarding fuel; you can get playa dust in your fuel when the cap is off, you pretty much ALWAYS spill fuel all over your generator when filling it up (because you can't see the tank and you don't know when to stop pouring) and running time can be short... an external fuel tank solves all three.

Go to a marine supply place like West Marine and buy a three or five gallon outboard boat motor tank. They're red plastic and match your Honda nicely, and they have a nice threaded fuel line connection.

Then go to an auto parts store, where you can buy some rubber fuel hose, hose clamps, and brass fittings that screw into the boat motor tank and attach the fuel hose. You can even buy a generic inline fuel filter to splice into your fuel hose.

Remove the little vent from the Honda's gas cap and screw the same type fitting you used at the external gas tank end of the hose into your generator's gas cap. You'll have to drill the hole in the gas cap to fit. Keep the hole as small as possible for an airtight fit. I screw a female-thread fitting on the inside of my gas cap just to tighten it down.

The way it works is - as the generator uses fuel, it creates vacuum in the tank, which causes it to suck fuel in from the external tank. I find it's helpful to elevate the external tank a bit higher than the generator.

Now you just fill up the external tank; you don't spill fuel all over your Honda, your fuel goes through a filter, and you have all the running time you want.
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Re: Evap vs Air Conditioning

Postby Elliot » Wed Feb 20, 2013 11:13 am

And for those with more non-mechanical talents, I believe you can now buy a ready modified cap, and even a complete kit, on eBay. :D
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Re: Evap vs Air Conditioning

Postby Colonel Monk » Sun Apr 28, 2013 10:08 am

Bunny,

Just have to thrown in my two cents here....

First off, don't be too intimidated by the evap cooler plans, they aren't that difficult... I did my own design last year, and I suppose the biggest challenge was finding the right parts because I didn't copy an established design..

I usually bring an RV, but as I'm currently living in it (burning man 24/7) I decided to rough it last year in my Honda element. I too, have a need to sleep until at least 2 or 3 pm so cooling was a must. I build a bucket cooler based on the usual designs and using a larger bucket for more water storage. I used a 4" hydro duct fan which worked way way better than any computer/silly little 12V fans will...

My camp has 120V AC, but this would have easily run off a battery or two and an inverter...

One thing you might be missing though in your plans, is that your 12V batteries are going to need DAILY charging. You can't just go with one battery and expect it to last the week, depending of course on your load. Car battery and a little computer fan? Sure, could just last the week with no charging. But a trash can swamp cooler running a radiator fan drawing 5-10amps power? Well, you might get one day out of a battery, but more likely you'd need two for a sleep session, and then you'll need to recharge it.

Solar is an excellent option in the desert, doesn't get any greener than that! You can expect a single 125-130W panel (think, 2 feet by 5 feet) under perfect conditions (no dust blocking the sun) to give you say, 7-10 amps of charging. Yeah, that might just run your fan! But for buffer sake, you're better off charging a battery with it for consistency thru the day. A new panel that size costs about $500 dollars and could cost an additional amount for the controller, depending.

You can probably charge your batteries with your vehicle..... But to do it right, I believe you have to use an isolator to charge it fast, otherwise the fresh battery in your car will fool the charging system into thinking it's charged..... Others may jump in and explain....

The other option, is to use a small gennie to charge your battery bank! So lets say, that you have a two battery bank to run your fans, and that you've planned your capacity to get you thru an entire day of cooling before needing to recharge. Once you get up, you can fire up your little honda gennie (the old 650W are still available used for a few hundred dollars) and run it for an hour or two to charge the batteries. You would want a relatively high power charger, like a 40A charger for an RV. You could run for a few hours and probably less than 1/2 gal of gas and you'd be ready for the following day.

OK, so just remember, even if you need batteries you still have to charge them. You need to know the power draw of your fan in amps, versus the capacity of your batteries in amp-hours. Once you know how much battery you need to run the cooler, you'll need to figure out how to recharge.

It sounds harder than it is. I'm sure, that if you posted your plans here someone can help you figure it out.

Good luck. And like others have said, please do NOT bring a generator that must run at 3600 rpm to generate power. There is no way for this to be quiet. The Honda EUs and copies are "inverter generators" and that's why the motor can run slower.

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Re: Evap vs Air Conditioning

Postby gyre » Sun Apr 28, 2013 10:25 am

The EUs are also variable speed, even more important.

I recently bought the cheap generator I mentioned somewhere.
Cost relative to a used smaller EU? 25% of the cost of a honda of about half capacity.
I still want a honda, but we can't all afford one.
It's a northern tool brand, has one speed and drinks fuel like crazy compared to a honda.
Reliable though, and reasonable loudness considering.
Far from the worst.

On the ac front, this is a little advanced, but in case anyone cares, I looked into traditional water cooled air conditioners in humid areas, like where I live (90% typically).
If the hvac advice I got is accurate, they are still effective in aiding standard cooling systems, even with humidity.
I was told I can expect 20-35% improvement with a large water cooling tower helping a traditional system.
Spraying water across the fins on even a window unit may be helpful, as the fins and blower aid evaporation.
Obviously, in a dry area this should work far better.
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Re: Evap vs Air Conditioning

Postby BurnerBunny » Mon Apr 29, 2013 12:13 pm

Let me make sure I'm understanding what you're saying: If I get a small AC unit, it might work better if I sprayed the back of it with water? Or also had an evaporative cooler running at the same time?

gyre wrote:The EUs are also variable speed, even more important.

I recently bought the cheap generator I mentioned somewhere.
Cost relative to a used smaller EU? 25% of the cost of a honda of about half capacity.
I still want a honda, but we can't all afford one.
It's a northern tool brand, has one speed and drinks fuel like crazy compared to a honda.
Reliable though, and reasonable loudness considering.
Far from the worst.

On the ac front, this is a little advanced, but in case anyone cares, I looked into traditional water cooled air conditioners in humid areas, like where I live (90% typically).
If the hvac advice I got is accurate, they are still effective in aiding standard cooling systems, even with humidity.
I was told I can expect 20-35% improvement with a large water cooling tower helping a traditional system.
Spraying water across the fins on even a window unit may be helpful, as the fins and blower aid evaporation.
Obviously, in a dry area this should work far better.
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Re: Evap vs Air Conditioning

Postby BBadger » Mon Apr 29, 2013 12:55 pm

Don't spray water on your AC unit fins. If your AC unit is working properly, the water will simply remain on the fins, or even freeze, and cause the unit to waste energy cooling water that does not need to be cooled. Worse, the water may cause additional corrosion and/or reduce the ability of your AC unit to remove heat from the air in the room due to an insulating effect. If you simply must cool yourself with some water, spray yourself with a spray bottle, so that whatever evaporates takes the heat from your body -- but don't put it on the AC unit itself.

You'd also be defeating one of the advantages of using an air conditioner over an evaporative cooler: the AC unit removes humidity. Humidity is the enemy. Even those evaporative coolers rely on the fact that you can remove the humidity through some other process like airflow. Spraying the humidity-removing device (the AC unit) is like pouring water on a drain in a bathtub to make it drain the rest of the water faster.
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Re: Evap vs Air Conditioning

Postby gyre » Mon Apr 29, 2013 6:01 pm

No, his advice was about the outside section which he said is sometimes designed to do this with water from the inside.
Not really practical for portable use.
It may be useful for someone with a marginal capacity unit, needing an edge.

I'm not so sure an evaporative unit wouldn't work at the same time as an ac unit (in extreme low humidity like the playa), though I agree you wouldn't want it anywhere near the ac blower.

Our discussion was primarily about 'built in place' cooling towers.
He actually did this recently for a grocery store.
It's practical for a home central unit too, if you're inclined.
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