Shade the condenser?

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  #1  
Old 05-31-02, 11:28 AM
Performin Norman
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Shade the condenser?

I was just curious if it does any good to have your condenser shaded. At my old house, they said it was good to have my AC on the North side of the house so it didn't see much sun, however in my new subdivision, all of the condensers are on the south side of the house. The sun just beats on it all day long. Does it make a difference?

Thanks for your help in advance.

PS. I have a guy coming over today to do a load test and see if my AC is underpowered. He said he can install a dual condenser system if he has to. Ever heard of that type of system in a residential application?
 
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  #2  
Old 05-31-02, 12:23 PM
PHnd
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Air conditioners are made to be left outside. Its all in their design. Anything that can be saved by shading cannot justify the cost... Save your dough
 
  #3  
Old 05-31-02, 12:48 PM
ahasbeen
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The sun is not a factor on any condensing units. Air temperature might be, but not the sun. As for the guy thats going to determine whether or not you're "underpowered" and will install a dual condensing unit if needed.........forget about it! Call a real HVAC technician to do a heat load and take his recomendations. For about 40 bucks you can do your own heat load online too.
 
  #4  
Old 05-31-02, 12:52 PM
Performin Norman
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Thanks for your replies. The guy that WAS supposed to come over and didn't, was supposed to do a load test. I guess he got too busy to come by.

Thanks again.
 
  #5  
Old 07-25-02, 04:36 PM
Shepiii
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Shading / Cooling the condenser

I live in Dallas, TX and have often wondered if shading or otherwise cooling the condenser would help. My condenser is unshaded on the west side of my house and takes a real beating from the sun on 100 degree days. As a matter of fact, the whole house is affected by the lack of shade to the west, and on 95+ days my 2 year old, 3 ton a/c unit can't quite keep up. Inside temps will rise to around 80 on the hottest days.

I haven't tried shading, but today I did try lightly spraying it down with a garden hose while monitoring the temperature of the air flowing from the a/c vents and the results were interesting.

With an outside air temp of 100, before hosing down the condenser, the air was a steady 68.2 degrees. After hosing it down for 5 minutes, the air temp had dropped to 64.0. I think it's safe to say that 4 degree cooler air would make a decent difference to inside temps and a/c efficiency.

This makes me wonder if I shouldn't put in some type of system that mists water onto the condenser in the afternoon. It wouldn't be too difficult and the water cost should be minimal. Then I got to thinking...the evaporator unit constantly makes water as it runs, which is currently piped to a drain inside the house. What if I were to re-direct this water to drip/spray onto the condenser? This water is much cooler than what comes from the tap, so even though it would be less in quantity, it might accomplish the same thing and would not add anything to my water bill.

I assume the condenser is unaffected by water since it's outside anyway and is exposed to the elements. This sounds just crazy enough to work? Has anyone else tried it?
 
  #6  
Old 07-25-02, 04:52 PM
bigjohn
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Please DO NOT put a water spray on your a/c unit. Here's why. The heat from the unit evaporates the water but the minerals in the water stay behind to scale up and clog the coil. Once the coil is clogged up with scale, you can't clean it out. About 20-25 years ago, this was marketed in Florida to homewners. These guys would custom build a contraption out of PVC pipe and secure it to the top of the unit. The homeowner would just hook up a garden hose to it. A WHOLE lotta folks wound up having to replace their outdoor units. The water from the drain is supposedly mineral free but I wouldn't test it on my unit. Besides you probably won't get a sufficient quantity of water from the drain to do much good.
 
  #7  
Old 07-25-02, 07:23 PM
Koolness
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Thumbs down Shading

I am a Florida A/C contractor. we actually tested a couple of units by shading the condensors and found that there was very little to no difference at all.

Kool
 
  #8  
Old 07-25-02, 07:50 PM
lynn comstock
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The reason why shading the unit makes little difference.

The outdoor unit fan moves about 1000 cfm (cubic feet per minute) of air through the outdoor unit for each ton of cooling. Thus a 3-ton unit moves 3000 cfm). That is a LOT of air (about 3 bedrooms full every minute).

A small patch of shade over the unit is irrelevant because hot air is being pulled into the unit from well outside of the shaded area. If the area is in a grove of trees, the air pulled from the shaded area will be cooler and that would make a difference.
 
  #9  
Old 07-25-02, 11:32 PM
Shepiii
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Cooling the condenser

Well, my test seems to prove that cooling the condenser helps. Although I havenít tried shading the unit, I agree that it probably wouldnít do much good. If spraying the thing down with 75 degree water only lowers the output temp by 4 degrees, then it stands to reason that shading alone wouldnít make a noticeable difference. The volume of air moving through the condenser is more than I could possible shade or cool, and will always be hot, so thatís a given.

But it is apparent that lowering the temperature of the condenser does also lower the temperature of the air blowing out of the vents. BigJohn states that normal tap water will cause another problem of scale buildup. Although this is cause for concern, this isnít something I would do year round, just on the 95+ degree days. If that means Iíll have to give the condenser unit a good scrubbing once a year, then so be it.

The temperature of the water in the evaporator drain has got to be around 40 degrees. Maybe 40 degree water trickling on the unit will be as effective as 75 degree water being sprayed all over. I can easily test this without doing any re-routing of pipes by using a pitcher of ice water and dripping it on the unit at a rate similar to that of the evaporator drain.

My test lasted 5 minutes and sure seemed to give good results and I have to wonder why nobody has designed a condenser unit with water assisted cooling. Iíll do some more testing and post again in a few days.
 
  #10  
Old 07-26-02, 04:05 AM
ServiceGrunt
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Shade it. Think of your poor service tech working on something that is so hot you can fry an egg on it! The shade has to help. Just don`t block the airflow above the unit or on the sides. It will also help keep your paint job on your unit from getting sunbleached.
 
  #11  
Old 07-26-02, 06:13 AM
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My test lasted 5 minutes and sure seemed to give good results and I have to wonder why nobody has designed a condenser unit with water assisted cooling. Iíll do some more testing and post again in a few days.

DO NOT do this test! your outdoor unit is not designed to use water for cooling.... Some area of the coils are very warm/hot and if you put water on it, it will dry up fast...and leave a lime or some type of deposit.. (Like boiling a pot of water dry! What is left behind??? Yes.. lime.and mineral.. water marks..) I've also heard the line cracking by doing this.. This is caused by tempature shock of the hot lines and cold water.. If you want a water cooled condensor, go and buy a water cooled condesor unit. Only area your going to see a water cooled unit are ground source heat pump.. That uses the same water that is pumped though the tubes underground. Water cooled units are not really found anymore cuz they take too much water.. (Air is free, not Water!) About the only place you are really going to find one is in an very old Cafe place.

So, the best thing to keep your unit at it's peek is just spray the coil with the unit OFF once a month (or often if you have cottenwood seeds making a blanket on it!)
 
  #12  
Old 07-26-02, 07:38 AM
Shepiii
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I appreciate the advice but if water is so bad for the condenser, why doesn't rainwater damage it? I don't turn mine off if it's raining.
 
  #13  
Old 07-26-02, 08:02 AM
PHnd
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I have to wonder why nobody has designed a condenser unit with water assisted cooling. Iíll do some more testing and post again in a few days.
This is nothing new to the industry. The fact is you cannot make this properly work. You will however shorten the life of that 2 year old a/c from 15 or so years to 6 or 8. The more water you put on the coil the more damage you'll do to it. Each year from here on out it will become less and less efficient to the point you'll have to have it replaced or you'll outright kill it.

The best you can do is make sure your filters are clean and vents open. Balance air between warmer and cooler rooms. Check your ducts and seal any leaks, especially around the return air. Don't wait until it's 85 or so inside to turn the a/c on, it is not designed for that kind of recovery. Wash the outside condenser at the beginning of the season and possibly in the middle. Other than that have it serviced professionally and be sure the charge is checked by superheat.superheat Superheat only!

Phil

Five people before me have explained to you not to fart around with your a/c but you continue to ignore them. Something is wrongt with this picture.
 
  #14  
Old 07-26-02, 09:05 AM
Shepiii
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Gee Phil, I must be stupid then right? Five people who I donít know from Adam tell me water cooling the condenser might have undesirable side effects, yet Iím still asking questions and running tests.

I take 5 minutes and spray a little water on my condenser which sits outside and endures torrential rainstorms all year round, and I discover that it cools better. To me, this warrants looking into. As I said, I appreciate the advice, but I generally rely on empirical evidence before drawing my own conclusions. Maybe Iíll screw up my condenser, or maybe Iíll invent a way to do this without the side effects and get rich on the patent. I might discover that adding two drops of Tang to the cooling water prevents scale buildup. Who knows?

If all the great inventors over the years stopped trying just because someone said ďit canít be doneĒ, then we probably wouldnít even have air conditioners. What a crazy ideal, suck in hot air, pass it over a coil with some magic stuff circulating inside called Freon and out comes cold air? Sounds preposterous, doesnít it? Fortunately for most of the non-forward thinking population, there are people like me who are willing to experiment and try to think up ways to make things betterÖoften drawing inspiration from being told ďit canít be doneĒ. We more often fail than succeed, but at least we try and there is no call for your condescension.
 
  #15  
Old 07-26-02, 11:00 AM
telco tech
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Shepiii, you're are on to something with the water cooling, but,.. it seems to be fairly well proven that the water that you use (tap or well water) does contain minerals, and that it will leave mineral deposits (scale) on your cooling fins. This effect will outweigh the benifits of the water cooling. Once the fins are scaled up, the unit will lose capacity no matter was the temp is. And this scale is HARD to remove without harsh chemicals. Rain water the unit is exposed to year round probably does not have the mineral content the tap water does, after all it is formed from the evaporative process, collects in clouds, falls back down etc. The minerals are left behind when the water evaporates. Just like they would on the cooling fins of your AC. When it rains on my car and then dries, it might leave a little dust behind, but it I wet my car with water from the hose and let it dry, I get little white mineral deposits. So,,, if you had a supply of mineral free water to use (distilled water, about .50 a gallon) it make work great without ill effects. The condensate water might work, but you might not get enough of it.
 
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Old 07-26-02, 11:16 AM
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Rain water is not tap water. Rain water is pretty much distilled water, in the sense that there are very few minerals in it. Tap water has a lot of minerals (that's why you put a filter on the line). It's up to the customer whether they want to "shower" the condensor. It's true, you will get a slightly cooler freon, and thus a slightly lower temperature inside. But you have to realize that you're adding the cost of water to the cost of electricity. While your AC will run perhaps a bit less, I don't believe that costwise you'll be any better. To top that off, water tends to be the most expensive where the temperature is the highest, and where most people contemplate this "cooling" effect. Most showers will get the infamous "film" in a couple of days (on glass, which is a very smooth surface). It's to be expected that the same film will build on the coil, and that film will not come off that easily. And it's a thermal insulator also. If somebody has a humidifier with a sponge belt and looks at the sponge after a while you'll have an idea of what the coils will look like also.
 
  #17  
Old 07-26-02, 01:22 PM
PHnd
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The difference is great inventors ask questions, get answers, do more research and ask more questions. You on the other hand asked the first question, received answers, ignored them like these people don't exists and went on about your business because you didnít get the answer you wanted to hear. Frankly, I think you should apologize to these folks for being so rude.

Now to give you a tid-bit of info; your unit sitting in the rain means nothing more than its constructed in such a way that the elements won't harm it. That's it. When you spray water on a running condenser you cause evaporation. A tremendous amount of heat is removed through evaporation but the impurities are left behind. The ill effects will be scale, which insulates the coil surfaces. At the same time the scale causes corrosion that will start eating at the coil making the situation worse. Once that process starts, its like rust on iron. In 2 or 3 years a 12 SEER condenser will run at about 8 SEER. Thatís the obvious. The not so obvious will be compressor damage because of drastic pressure changes within the operating system. Itís been tried, wet coolers, dry coolers, spray, you name it.
 
  #18  
Old 07-26-02, 01:46 PM
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Some suggestions:
(1). If the condensor case is dark color and under direct sun, make it light color.
(2). As Lynn said, grove of trees does help. No water cost. Trees reduce air temperature by block sun and eveperate water.
(3). Do not apply water direct on coil but to surrounding rugs as in eveperation ACs (swamp ACs). less water will be wasted by using rugs. Do not let rug block air flow. People claim eveperation ACs are cheapter to run than regular AC, but they are only suitable for dry climates when used indoor.
 
  #19  
Old 07-26-02, 04:24 PM
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Lightbulb Water cooling

Actually the evaperative effect of the water redues the tempature of the condeser to just above the dewpoint of the air.

Water cooling is used extensively in commercial applications (hotels, malls etc) for higher efficiency, however the units are desinged from the beginning with water cooling in mind.

Also the maintainence is much more frequent with these units and most residential customers aren't going to do it after the first year or so.

Don't ruin your condenser by using water cooling,.
Hmmm, I wonder if they will ever make a water cooled unit in the 3-5 ton range, all that are made now are 10+ tons "water chiller" units for commercial appliacations
 
  #20  
Old 07-26-02, 05:32 PM
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Good point about dewpoint for eveporative ACs.
I have a 3T gas central AC system by Arkla-Servel (Robur) using Ammonia as refrigerant and water heat exchanger indoor (water filled A coil above furnace). I believe that some commertial "water chillers" are similar to home gas ACs (absorption ACs) - which use Ammonia as refrigerant and water for heater transfer.
 
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