AC Pre-Cool Mist System-Residential


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Old 06-10-09, 01:28 PM
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AC Pre-Cool Mist System-Residential

Has anyone used this system to cool the AC system?
Misting Systems from Mist Cooling Inc
 
  #2  
Old 06-10-09, 01:32 PM
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I'm sure they have or they would not sell them. I for one love them because they will eat the coil up on the unit and I will get to install a new unit.
 
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Old 06-10-09, 02:37 PM
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Why would the water eat up the coil if its filtered?
 
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Old 06-10-09, 04:00 PM
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Model MC 601 Poly-Phosphate Filter Attaches directly to your hose Bibb. 5 micron sediment filter with poly-phosphate element helps keep nozzles clean in areas with hard water. Inlet: ¾" FHT Outlet: ¾" MHT

Polyphosphate is a soluble mineral compound have been used as an alternative form of hard water treatment which acts as a sequestering agent when added to water. Sequestering is simply the ability or tendency to tie up and hold in solution other minerals such as scale causing calcium and magnesium. The polyphosphates form bonds with scale causing minerals which make them more water soluble. Therefore, the hard minerals act soft and remain in solution, as opposed to depositing scale. Polyphosphates also change the shape of the scale causing molecules which does not allow it to cling and prevents it building up on itself and minimize the cloging of nozzles.

The above is their take on the filter. I copied/pasted from the webite. Notice how the ployphosphates make the minerals more water soluble and the molecular shape of the minerals is changed to make them less clingy. The filter is there to cut down on nozzle clogging. What do you think happens to the minerals when the water hits the hot condensor coil on your a/c and the water evaporates? The minerals can't evaporate, they get left behind to scale up the coil. Notice also how the sales pitch only addresses minerals in the water. What about the other stuff in the water like chlorine? Chlorine is corrosive to metal. These things come and go every few years. It seems like they go off the market when people have to start replacing their units from using these so called energy savers and the sellers get sued. If this was such a great idea, the a/c unit manufacturers would not only endorse them they would put them on their units as standard equipment.
 
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Old 06-10-09, 04:41 PM
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Phosphates are sometimes used as water treatment for commercial ice machines but this form of water treatment doesn't work that well.
It will slow down the formation of scale but only slightly.

If you were to use phosphates on the mister airman would have to wait a year longer to sell a new unit.
 
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Old 06-11-09, 09:06 AM
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There goes GregHs cut of my job!
 
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Old 06-11-09, 06:06 PM
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Looks like a good way to slug a compressor or freeze up an evaporator. Would only use it in very hot conditions.
 
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Old 06-11-09, 07:10 PM
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Thanks guys, I am convinced its not a good idea.
 
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Old 07-16-09, 09:29 AM
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I'm not convinced.

I just registered for this site because I'm convinced pre-cooling an AC unit is a good idea...but that it needs to be done with purified water.

I also want to add outdoor misting to my patio area, but again, believe it must be done with purified water.

My question is, what is the best-value-system for purifying my water?

I have a soft water system. Is there an add-on that I can use to remove the salt?

Or I could use my non-soft water line and wonder if a separate RO system would provide better water for misting. Or maybe there's something altogether different that would work better.

Obviously, I'd like to keep costs as low as possible, including filter replacement costs, while ensuring the job is done properly.

Any suggestions?
 
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Old 07-16-09, 01:33 PM
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"Obviously, I'd like to keep costs as low as possible......."
This statement pretty much throws out using evaporated water as a cooling aid.
Reverse osmosis and economical water treatment is a contradiction in terms.
As good as water would be, if it were economically feasible, believe me, more would be doing it.
A practical alternative would be an oversize refrigerant condenser on a central a/c unit and better insulation and windows.
 
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Old 07-18-09, 11:23 AM
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Thanks for your reply, Super Moderator

My family is already pushing me toward an RO system, so cost isn't the only concern.

I could supply mist valves with soft-water from my already existing system at no additional cost. Would soft-water damage my AC unit? I'm afraid it will kill my vegetation? Can I filter out the salt?

My entire house is on soft-water, both hot and cold, except for one kitchen, drinking/cooking water faucet and the refrigerator. My family would like me to put a filter on this isolated kitchen faucet (the refrigerator already has one).

Costco has a reverse osmosis system on sale for $350, but that's not worth it to me if it were to be used only for the kitchen faucet. However, if the soft water isn't good for a misting system, or if the RO water would be much better, then I'd be willing to shell out the $350.

However, I'm concerned that the RO system might not provide enough pressure for misting my outdoor patio and AC unit. Does anyone know about the pressure of an RO system?

If I go ahead with an RO system, I'm still wondering if it would be bad to cool the air around the AC unit?

I don't know what the service life and replacement costs would be for the RO filters. If they were to add up to, say more than $100 a year, then I might not want to do this.
 
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Old 07-18-09, 12:17 PM
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You are welcome, Member

To use any kind of water cooling on your air-conditioner you will use a considerable amount of water.
A home RO system is very inefficient in that you could have anywhere from five to ten gallons of waste water for every gallon of water produced.
Also, unless you have a reservoir and pump the pressure off the RO filter would be too low.

To use soft water and not worry about your lawn you could switch to Potassium Chloride as a regenerant.
Potassium chloride acts as a fertilizer so the downside is more grass cutting and higher costs as it is more expensive than Sodium Chloride..
Unfortunately the aluminum fins on your a/c wouldn't care what form the salt is and would corrode just as quickly.

The idea to cool an a/c with water is a good one but unfortunately the laws of budget, physics and science are not on your side.
 
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Old 07-19-09, 05:34 PM
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Thanks So Much

I didn't know about the waste water produced by using an RO system. They don't put that kind of information on the RO product descriptions.

And now I understand why all the mist system descriptions only talked about filtration to remove contaminants.
 
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Old 08-30-09, 01:47 PM
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Wink This can work if done right

After moving from the Midwest to California and having a huge increase in energy costs, I have done completed several tasks at my new home which have decreased my energy consumption by about 60%. The AC misting system I built is a bit more complex then some but works very well. I'll explain how it works. First, I tapped into an existing 1/2 cold copper line. I installed a ball valve for ease of control. This then feeds a portable water softener purchased through an RV supply house for about 75 bucks. The unit does an excellent job of removing minerals from the water and can be recharged with table salt of potassium, your choice. Lasts about 1000 gallons between charges which is about a full summers worth of use. Post the water softener my water line enters a 3/4 irrigation valve (I used Orbit but any 24VAC solenoid will do). Post the irrigation valve, I drop the water line down to 1/4" tubing and run the water through a polishing filter (5 micron). Post the polishing filter I run the 1/4 supply line into a booster pump which increases the water pressure to 125PSI. Post the booster pump I run the lines to my AC unit and mount four misting nozzles around the front of the air intake / condenser coil, no closer than six inches from the coils and pointing away from the AC unit. I control all of this my way of a 24VAC SPDT relay which uses the 24VAC cooling call from the AC unit to energize the relay coil. I then switch power to the booster pump and irrigation valve on/off using this relay. So the water used is clean, soft water...no mineral buildup at all. Second, the booster pump creates a cloud of 50micron or smaller water droplets which nearly of 'flash evaporate' in front of the AC unit, cooling the air itself by sucking the heat of of it...much the same way the refrigerant in the cooling system boils and sucks the heat of your houses air. So very small amounts of water actually make it to the AC unit and what does is cleaner than rain which all of these units are designed to run in....ever heard of a summer thunderstorm? Anyway, the whole kit cost me about $160. The unit when running consumes 28 watts and uses less than 2 gallons of water per hour. I have tested before and after and have the system reduces power consumption by approximately 25%, which on my unit is just over 500 watts in savings....so the 28 watts it takes to run this system is energy well spent. The water is a nit and won't even be seen on my bill as my AC now only runs (real run time) about two hours per day on the hottest days. That's like flushing the toilet three extra times a day or something....not big enough to consider. I wouldn't buy one those hokey AC cooling systems you see packaged on the Internet for sale but I know a well designed system does work.
 
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Old 08-30-09, 06:29 PM
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Run time of only two hours! So why even have AC?
 
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Old 08-30-09, 06:48 PM
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I believe he means a total of 2 hours, if each cycle only needs 10 minutes to reach the set target temperature, because the system is so efficient, then a total of 2 hours run time (12 cycles) is all he needs.
 
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Old 08-30-09, 08:49 PM
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Because it gets hot

That's two hours of actual run time. The AC cooler I developed is just one component of the overall solution I installed at our home. When we first moved here, on a hot day, our AC would start cycling on/off beginning around 10am. Now it does not begin running until about 4PM and when it does run it runs much more efficiently. I track our daily (overall household) KWH usage and graph that against daily temps. With our household enviornment held constant (e.g., thermostat setting, washing, cooking, etc..) I have been able to track the effectiveness of the changes I have implemented. Our PG&E bill has decreased over 60% since finishing these projects. So by itself, the AC cooling system isn't the answer but rather it the totality of all that I have done which has made such a signifiant difference. I just wanted to add my two cents to the thread about AC misting as many people have said how bad of an idea it is....in fact, it does work and does reduce your energy consumption and if done correctly will not adversely impact your AC unit.
 
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Old 08-31-09, 05:01 AM
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We are talking specifically about misting and not overall energy savings.

Your energy saving project sounds admirable but it appears as if your figures inaccurately credit misting with these savings.

Now it does not begin running until about 4PM
Your savings are from reducing your overall cooling load and not spraying water at your condensing unit.
 
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Old 08-31-09, 07:20 AM
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AC misting does help reduce energy foorprint

Its the overall system I installed which has reduced my energy consumption by 60% but the misting system, which by the way, does not spray water on the AC unit, accounts for between 20-25% of those savings.....Just giving those folks whom are interested in a misting system an account of one which is installed, working, and saving money....without causing my AC unit to dissolve into a pile of rubble.
 
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Old 08-31-09, 09:23 AM
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If your DIY system works, why did you say you would not buy the one on the market ? Isn't that one using the same theory ??
 
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Old 08-31-09, 11:09 AM
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You can buy anything you wish but....

A few things...I like the water flow control provided by proven, old school technology like an electromechanical relay which is controlled by the opening / closing of the cooling contacts on my thermostat...Works well and will last a long time. The unit I saw online looks like it used a glorified toilet flapper which relies on the AC exhaust to open and close the water supply valve. That didn't appeal to me. Second, I have installed an actual water softener and polishing filter that reliably removes minerals, sediment and chemicals from the public water system, the one I saw online came with a poly-phosphate filter which would provide marginal results at best. Third, I installed a booster pump on my system which increases water pressure from 50-60PSI (house side) to 125PSI (mister side) so that the spray from the nozzles is much finer, aiding in the flash evaporation of the water. Very little moisture reaches the coil array, instead air which has been cooled 25 degrees relative to outside ambient temp does...So on a 95 degree day the fan is pulling 70 degree air across the coil....It's not about getting the coil wet, its about cooling the air being pulled across it. Fourth, I'm a retired engineer and this was just a fun little project which will pay for itself quickly.
 
  #22  
Old 08-31-09, 11:50 AM
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cp...
I'm just wondering what other things you did..since the A/C starts 6 hrs later in the day? I presume insulation, windows, weatherstripping etc, etc.

And have you run the HVAC w/o the misting system to compare run times and power usage? You are an engineer..so I presume so..I know how you guys are...lol.

Just wondering....
 
  #23  
Old 08-31-09, 01:09 PM
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What else I did...

GunGuy45 - Yes, I did several other projects. First let me describe my home...single story ranch about 2000 sq. ft, concrete tile roof, wood siding. Some shade but mostly my home gets a lot of sun. This house would get freaking hot on those 90+ days. Traditional insulation is fine but adding any more in my house wouldn't have made an appreciable difference. I opted to install a radiant barrier in the attic which deflects about 96% of the radiant energy back out the roof line. You tack the stuff to the roof rafters, it comes in 24" rolls. I bought it at my local Home Depot store...I think a 24" x 50' roll was something like 25 bucks. Installing that radiant barrier did wonders for the attic temp. Then I purchased a garage / attic cooler from a company in Arizona. It's a fire-rated fan you mount in the ceiling of your garage which is activated by attic temp. It's very efficient, moving 1350 CFM with a 40 watt motor. I designed it so that the garage fan is pulling cool air from under the house (crawl space) and using that cooler air to drop the garage temp at the same time exhausting that cooler air into the attic. This creates a higher pressure envelope inside the attic relative to outside air which expedites the evacuation of hotter air through the attic eaves and gables. I then installed a solar gable fan at the opposite side of the attic which aids the garage fan by pulling the warm air out of the attic, one is pushing cool air in and the other pulling hot air out. My attic stays just about 10 degrees above ambient outside temps. This is main reason my AC doesn't turn on until later in the day. Lastly, I installed the misters on my AC system and yes I have done before and after tests on the system. Amperage draw and run times have decreased creating an overall decrease in air conditioning power consumption of roughly 25%.
 

Last edited by cpfullback; 08-31-09 at 01:11 PM. Reason: spelling
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Old 09-16-09, 08:55 PM
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Smile How do i get a parts list

CP,
Wow! I would like to build one of these.
are you using a 24 VAC booster pump?
I see some plastic and some brass nozzles. They are rated at .5, 1, 1.5, and 2 GPH at 30 psi.
most of the nozzles i find are not recommended for over 100 psi. You are at 125 psi. what nozzles did you use.
you mentioned a total use rate of 2 GPH , how did you get that with 4 nozzles?
When you state the savings of 25% = 500 watts that implies you are running at 2000 watts. That seems low for full power, how many Ton A/C unit are you using?
 
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Old 09-19-09, 09:30 PM
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The unit does an excellent job of removing minerals from the water and can be recharged with table salt of potassium, your choice.
I'm not so sure about this guys.
I'm not a chemist but aluminum and salt are mortal enemies.

Airman may LOVE this device, after all. Sounds like money to him.

In any case you can clean, massage and do whatever you like with the mist water but once it mixes with the AIR in and on your condensor it's going to be one messed up bunch of water.
Heck, the air isn't even fit to BREATHE in a lot of places.

I don't think I'd want my condensing unit dating one of these.
 
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Old 09-19-09, 10:00 PM
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This thread is becoming a snake oil convention!

With the big money being spent on energy conservation this whole concept would be mainstream if it had any potential.
 
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Old 09-20-09, 11:36 AM
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Second Attempt at Post

Interestingly, I tried to reply earlier but my post didn't seem to make it, perhaps a moderator deemed my post inappropriate although it is clearly mundane...I'll try again.

I had received a couple of emails indicating that there were some unanswered questions lingering on a post I had submitted about an AC misting system I created. After reading the posts it doesn’t appear there are any questions; rather a couple of people whom, without any data, indicate that it is their belief what I have proposed will not work. As Abraham Lincoln once said, ‘you cannot disprove Euclidean geometry by calling Euclid a liar’.

For those of you who are interested in the experiment I have conducted and which results I have shared I encourage you to try this. HVAC technicians are talented people but that doesn't make the devices they work on any more complicated than they are. In fact, residential AC systems are comprised of a few simple components whose function can be understood in a couple of hours of self study. I recommend doing a little homework, comprehending the components involved with what I have proposed and coming to your own informed decision, I wouldn't allow naysayer’s to deter you.

I contributed to this forum to help those who were interested in trying this as a method of saving energy and lowering their energy bills. I have no other motivation. I am a retired engineer who simply shared a DIY experiment which has saved my wife and me money on our electric bill. I’ve completed that task and am signing off. Good Luck!
 
  #28  
Old 09-07-12, 01:01 PM
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cpFullback is indeed correct. AC pre-cooling CAN be made to work

This thread was very interesting. As a degreed physicist and engineer with over 25 years of experience, I am VERY familiar with misting/AC pre-cooling systems. cpFullback knows what he is talking about and provided excellent advise on the subject. Some of the other posts in the thread, well...not so much.

Misting/AC Pre-Cooling Systems are rapidly being deployed commercially to reduce rising energy costs and have been for a number of years now. Google, Ford, Walmart, McDonalds, Boeing, (to name a few), have already deployed systems and embraced this technology today.

There are a few right ways and many many wrong ways to design and implement these systems. Treating the water is key and is also the primary reason that there is not a GOOD cost effective system being offered for the residential market today. Systems like those offered by******* for the residential market are NOT viable, primarily because they do NOT adequately address the water treatment issue and can cause serious problems after extended use due to scale build-up on the coil array.

RO and DI water delivery systems, while viable for larger commercial systems, are not economically viable for residential applications. That said, there is new physical water treatment technology that will enable the residential AC pre-cooling market.

The reason I know this is because I have spent several years working with many of the companies, technologists and leaders in this small niche space who will shape this embryonic industry. They will be delivering their first products to the residential market soon. I have heard so many people, (like the GregH's in this thread), tell us that this is just a bad idea, can't be done or shouldn't be done. Many are HVAC tech's who may know their equipment well, but have a very limited scope of technical knowledge and expertise in applied chemistry, physics or engineering.

So, I can say with certainty that:

1. AC Pre-Cooling CAN work, does work and is working well today commercially. The companies mentioned above and many others using it today are early adopters, not dummies.

2. Residential units that DO work well and provide an outstanding ROI are forthcoming soon.

3. Beware of cheap products like those offered by ******* and likely others in the future which do NOT adequately address the problem of water treatment and scaling issues.
 

Last edited by GregH; 09-07-12 at 02:15 PM. Reason: Remove company names.
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Old 09-08-12, 11:20 AM
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This thread is 3 years old. Well, since you bring this topic up again, I do have a question about the misting AC unit to save energy. In fact I believe this theory, 3 years ago I did a dumb but simple test by spraying water (use a garden hose) on the condenser unit and I was able to increase my Delta T from 16 degrees to 19 degrees in 3 minutes. Anyway, Here is my question. These days almost all window AC units spray condensation water back on the coil, How come they do not worry about the water damages? Is condensation water pure enough for this purpose ?
 
  #30  
Old 09-08-12, 11:43 AM
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Clocert...let me throw in...

I capture my condensate from my home A/C in containers. I sterilize it with a bit of bleach to take care of organics. After airing it out before use I use it to fill the containers of my water only plants. Much less mineral build-up on the glass containers. No idea about PH or anything like that.
 
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Old 09-08-12, 12:23 PM
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Yes, condensate from an a/c evaporator has a very low mineral content.....almost like distilled water.
It goes without saying that pure water misted on a condenser would be very efficient.
The complication is that to treat water to this purity makes misting a hard sell.

Using water to cool a/c is not new.
At one time what was quite popular in commercial installations and still is sometimes used is a water cooled condenser.
This uses water to directly cool the condenser and then discharged the waste water to the drain.
They are still occasionally used in some applications.
One added benefit to using water cooled equipment is that the operating conditions for the condensing unit are quite stable and this equipment has an exceptionally long life.

An improvement on this technology is to use a water cooled condenser but have the water circulate to a cooling tower where the heat is removed by spraying or running the heated water over slats.
Very common in large buildings but not efficient on a small scale.

We could hope that some new water treatment method is developed to make this practical but if it does it would likely get lost in the pseudo-science that plagues the water treatment industry.
 
 

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