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Will running cold water on Central A/C improve cooling?

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Will running cold water on Central A/C improve cooling?

Old 06-29-2018, 08:20 AM
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Default Will running cold water on Central A/C improve cooling?

Our old Central A/C was undersized for the size of our house. In order to help the unit cool more I ran a mist of cold water on the cooling fins of the heatsink/radiator and it seemed to make the air cooler coming out of the registers but I never measured the air temp.

We are supposed to have temps over 100F the next couple of days so I know our 6 year old central A/C will be running continuously to keep the temp in the house around 76F. We have well water & it's very cold all the time so my logic is if I mist the cooling fins with cold water it will allow the A/C to produce cooler air. Does anyone know if this will actually help the A/C work better or just a waste of water?

I did clean all of the Cottonwood out of the cooling fins so that will help but will misting with cold well water help anything? I did do searching online & the information seems very contradictory that misting works or misting does not work.

Last edited by RussH; 06-29-2018 at 08:30 AM.
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Old 06-29-2018, 08:24 AM
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This is going to get good
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Old 06-29-2018, 08:26 AM
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Old 06-29-2018, 08:31 AM
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So the answer is not enough to make a difference.

If you have a properly balanced system and it is charged and functioning properly then there should technically be an 18-20 degree split.

What that means is if your air being sucked in by your unit thru your return is 70 degrees your unit should be blowing out air thru your vents at around 50 degrees.

putting water on your coils will do other things for you BUT will not make a huge difference in your output air

my suggestion. Make sure all door gaps are tight and put curtains over your windows even if just temporarily
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Old 06-29-2018, 08:32 AM
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Please specify if the condenser is inside or outside so we can provide the best guidance.
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Old 06-29-2018, 08:32 AM
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It will help until the scale from the water coats the coils and then they will be junk.
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Old 06-29-2018, 08:40 AM
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A few years ago, I was looking at this question myself. We used a timer to see how long it took from the time the a/c kicked on, until it kicked itself back off. After we did that a few times to get a baseline reading, we then kept a constant spray of water on the unit, and again timed it. With a constant stream of water, the difference in time was drastic. I forget the numbers now, but it was a huge difference. And the air blowing from the vents was cooler as well. We didn't end up buying one of those mister setups, but I would be curious to know, after paying for system, and the water, what the real savings is.
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Old 06-29-2018, 08:42 AM
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Roof misters would be a much better use of the water.

We run a web of 1/2 gal/min misters in tip of our plant, which is not air conditioned. 16’ wall height 22,000 ft metal building. At floor level this is good for an easy 10 degree temp drop.
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Old 06-29-2018, 08:43 AM
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In theory, misting the compressor coils with water will carry the heat away faster and make the compressor unit more efficient. In practice, I'd listen to the guy who talked about scale buildup.
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Old 06-29-2018, 08:54 AM
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The guy in the video above says the kit he bought comes with a filter, which is good for six months. I guess if you have the discipline to change the filter every six months, that would resolve the scale problem. Personally, I don't even change my air filter as much as I should. No way I'm going to be going outside changing the water filter too. And just how much does a new filter every six months cost?
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Old 06-29-2018, 09:05 AM
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Yes it condenses your gas at a faster rate BUT ever wonder y ppl with money don't put oversized units in their house?

The answer is because an AC system works as a dehumidifier. An oversized system would run until it satisfied the T-stat but not long enough to pull the humidity out of the air. So it would then in turn come on quicker and repeat the process. The same principles apply in this situation.

Use the the extra money that u would spend on water to attempt to keep the cold air in and the hot air out.
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Old 06-29-2018, 09:07 AM
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I simply put a sun shade about 4' over the unit as it is in direct sun most of the day. It does improve cooling
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Old 06-29-2018, 09:10 AM
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Originally Posted by 2_gator View Post
Please specify if the condenser is inside or outside so we can provide the best guidance.
Condenser is outside.

Originally Posted by savage25xtreme View Post
It will help until the scale from the water coats the coils and then they will be junk.
I'm not concerned about getting any scale build up because I'm not planning on running water on the A/C all the time. Our water runs through a softener and we don't have any scale build up anywhere else in the house so this isn't a concern to me.

Originally Posted by Turtle9343 View Post
The guy in the video above says the kit he bought comes with a filter, which is good for six months. I guess if you have the discipline to change the filter every six months, that would resolve the scale problem. Personally, I don't even change my air filter as much as I should. No way I'm going to be going outside changing the water filter too. And just how much does a new filter every six months cost?
Again I'm not going to set up a misting system and don't plan on running water on the unit on a regular basis. There are just as many video's saying it's a waste of time -vs- saying it works great. I watched several You Tube videos before I posted this.

Thanks Turtle for the info, I am looking for info from someone that knows from experience or that is an HVAC person not just someone guessing.

Our well water isn't like city water, the water is always very cold so logically I would think because the water is so cold that it should make a big difference.
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Old 06-29-2018, 09:21 AM
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Originally Posted by Gullpt View Post
I simply put a sun shade about 4' over the unit as it is in direct sun most of the day. It does improve cooling
Exactly.
My outdoor condenser was behind my home in full sun from sunrise to about 5PM in the afternoon. When I installed a deck on the back of the house, it created a shady spot and the condenser is now never in direct sunlight. My electrical bill has dropped about $25.00 a month during the hot season from when it sat in direct sunlight.
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Old 06-29-2018, 09:34 AM
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Yes it works very well with marginal or systems that are limping along

it is an old trick for big commercial roof top packages that are struggling.
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Old 06-29-2018, 09:45 AM
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A six year old unit that is undersize. What you need is a new 16 seer unit that is a 1/2 ton over.
I had an old 4 ton on a house that really needed a 4 1/2. I just replaced it with a 16 seer 5 ton and the bill has dropped over 250 a month and I keep it 1 degree colder. In all fairness. I also put a new tile roof on the house which contributed but in the month between the new AC and the new roof the bill was still 200.00 lower that it was
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Old 06-29-2018, 09:52 AM
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Hell, out here we just run water through pads and suck the air through it. It's called "evaporative cooling." Had one on the roof for years and it's so much cheaper to run than the AC.

Then again, Russ... you have this nasty thing called "humidity" that we don't have here. I mean, if we push 10% humidity today, that will be a lot. The evaporative cooling effect only works to a dew point of about 55 degrees. Once the humidity gets that high, you're just blowing hot wet air around and you HAVE TO go to AC for any relief. But normally, an evap cooler will give a 20 degree drop. When it hits 110 here like it has been all week, screw that. The best temp you're going to cool to is 90! Plus the amount of scale (even with scale prevention liquid added) is off-the-hook.

I know this is different than what your talking about, but some of the same things do apply. I can say I've never seen spraying the coils in use or recommended here and when it comes to hot, we wrote the damned book on it.
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Old 06-29-2018, 10:07 AM
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Yes it would but not 100% sure it's a good idea. The evaporation of the mist in the air around the unit would cool the air; increase the temperature differential and thereby increase the thermal efficiency of your unit. The water on the coils would transfer heat from the coil far better than air and again be more efficient. Some of the factors mentioned like relative humidity and air flow would factor into how much you gain so without factoring in all of the variables it would be hard to tell unless you actually measure the change in air temp from your ducts before and while doing it.
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Old 06-29-2018, 10:50 AM
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Can you commercial ac guys explain cooling towers to these guys.

neighbor owned a vommercial building that used a cooling tower that works on the same principle.

putting a 125 cubic foot canopy of shade won’t do shit.
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Old 06-29-2018, 11:56 AM
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Well I can answered my own question. The air coming out of the register was 55,7F before turning on the water and since misting the A/C the air temp went down to 42.6F. I would say that is a VERY significant change. Our well water coming out of the faucet is 50.5F so the air coming out of the registers is colder than the water I am spraying on the A/C.
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