Water cooled air conditioner?

[BioHazard]

I got a free 10k BTU window air conditioner for the shop. It's not really big enough but it's better than nothing. At my shop I get "free" water, it's a commercial place and it's included with my rent. I was thinking, what if I install a small sprinkler on the back of the condenser? The water comes out of the tap at around 60 degrees in the summer...that's a lot better than trying to cool it with 80-90 degree outside air! Would that make the air conditioner more efficient, not counting the cost of the water? I figure the outside part of the air conditioner is mostly water proof...wouldn't be much different than a rain storm. I could drain the excess water off into the grass so it wouldn't really go to waste...

What do you think?

 

[redsky49]

You would be better off by trying to provide some shade for the unit, or locating it on the north side of the garage.

As a matter of fact though, water has been used in the past for cooling, with systems designed for (primarily commercial) flat roofs. In those applications, sprinklers would spray the roof and, via evaporative cooling, lower the roof temperature, thus reducing the cooling load on the structure. These were popular in very dry areas, but as the cost (and value) of water has increased, they have disappeared from use.

For the best efficiency of your unit, ensure that any filter is clean, the coils are kept clean and the fins straightened, and that the supply air discharge is not obstructed. Allow plenty of air circulation around the exterior of the unit.

As always, offered only as opinion

 

[y20dth]

It wil make it cool better, yes.
We used to do this on industrial cooling units when it got really hot.

 

[CraigFL]

Technically, the efficiency of A/C units go up as the outside temperature goes down. This means if you can fool the unit into a lower temperature by spraying cool water on the coils, the increased efficiency will save you money by cycling on and off less. Usually water isn't "free" for most so this would have to be included in the analysis as well as the efficiency increase. So if your water will truly remain free, your electric bill may go down slightly although it may be so small that with the changing conditions, you may not even notice it.

 

[texasOFT]

Put one of those patio mist nozzles on the a/c unit spraying away from the unit so it will cool the air being drawn into the coils. It will reduce the load on the a/c unit. Will also work on house a/c unit outside but may require multiple misting nozzles. Can also add a water valve unit that is activated when the hot air is exhausted from the unit. Use a evaporative swamp cooler water float valve with a paddle to replace the float that the exhausting air will lift the paddle opening the water valve. Will only use water when the a/c unit is exhausting hot air.

 

[AV8OR]

I made my own version of these ten years ago to limp the old compressor on through "another" summer thinking that "next year" we might get an all-new A/C system. During July and August I ran the misters from 11:00 in the morning to 11:00 at night.

I could tell the difference when the misters were on and when I had forgotten to turn them on. No scientific data other then the house going from full roast to gentle boil.

Last spring we changed out the old system for a new Trane unit and have the compressor actuality cycling on and off during the day. What a concept!

I made mine out of Arizona Misters that came in pre-tapped 1/2" PVC couplers and 1/2" PVC pipe. I made a box out of the PVC pipe that I could remove from the A/C unit for servicing. Two misters on the top and two on the bottom spraying into the incoming air. The only downside I had was the water mixed with all the other junk floating around in the air made a hard crud that collected on the cooling fins. You need to take the covers of the compressor at least each spring and give it a good flush. Toward the end of summer it was a little swampy around the compressor but I planted mint for the ice tea to take advantage of the swamp.

Another thing I read is to weld a platform for the compressor which gets it up to around 18" off the ground. I read this keeps the grass clippings and other junk from collecting on the fins. Seems like a good idea for what is now required equipment living in the south.

At the hose bib I put a flow restrictor that you put on drip irrigation systems. It is like a hose washer but with a much smaller whole drilled into the disk and was rated at four gallons an hour. I put it where the hose attached to the hose bib. That way if the hose did burst I wasn’t going to pay for hundreds of gallons of water as I flooded the hood. 

During the summers my compressor ran all day so I didn't have to worry about the misters cycling on with the compressor. One of the links has a method of splicing into the A/C wiring but I could see a micro switch from Radio Shack and some sort of peddle that got blown up in the airflow that would make the connection. The electronics on this would exceed your material cost and would also buy a lot of water. Home Depot landscaping department carries a pack of drip irrigation restrictors and the different colors are for the different flow rates.

More info and one mentions of concern about mineral buildup on the coils if you have heavy water.

http://forum.beyond3d.com/archive/index.php/t-21760.html

http://www.marylandgreenpower.com/g...30-more-for-air-conditioning-than-businesses/

http://www.keepmaster.com/homeprojects/homeNew4.html

http://www.mistcooling.com/acprecool.html

http://www.coolnsave.com/

 

[mustangmccance]

If you live in a dry climate a swamp cooler is what you need. it will cool and add moisture to the air. very popular in southern utah where I used to live. they are also pretty cheap.
I believe that is what redsky was referring to. they may not be common in other parts of the country but in really dry places like southern utah you see them all over.

 

[bradleys]

BioHazard,

Before you spend too much time fooling with external water cooling, look closely at the unit you're acquiring.

I bought an 8000 btu unit a couple of years ago that has "internal" water cooling. The condensation water from inside goes to the outside of the unit, and then is blown through the outside coils by the fan that cools those coils. I can feel very slight water drops/spray when standing right by the unit. There is NO drip-drip-drip like on traditional units.

 

[malibu101]

Like bradleys said- I have an Emerson Quiet Kool 18K for the downstairs of the house. Got it about 4-5 years ago. Works great.
Anyway, I remember it having a "warning" sticker that it would not drip water. It explained that the water is picked up by the fan and blown against the coil to help cool it. And it does not drip, just like they said.
I take it in and out every season and the coil appears perfect. No scum or buildup from stuff in the water.

 

[Born_Annoyed]

The last shop I worked at had one of these. As you can guess it get's freakin hot in S-Florida and the Humidity is well let's just say you can cut it with a knife. A little pricy but to have cool air on those hot days it's worth it...

 

[tcianci]

As others have mentioned, the AC unit itself produces a fair amount of ice cold distilled water. Even though your water source is free you would do well to take advantage of the free cold water inside the unit to do the additional condenser cooling as it is is condensed from the air and therefore is mineral free.

 

[BioHazard]

I bought an 8000 btu unit a couple of years ago that has "internal" water cooling. The condensation water from inside goes to the outside of the unit, and then is blown through the outside coils by the fan that cools those coils. I can feel very slight water drops/spray when standing right by the unit. There is NO drip-drip-drip like on traditional units.

Yeah, the newer ones do that for efficiency - only makes sense rather than just letting the condesation water drip out. BUT it's still nothing like running the hose over the condensor, it's only a few drips of warm water, as opposed to gallons of cold water. I've tried dumping water on the window units at home before, seemed to help temporarily, but I never used much water since I had to pay for it!

I've been using a 5k BTU air conditioner in my shop as a dehumidifier, it is also the "dripless" type. But I drilled a little hole in the corner and put it over a bucket - it makes a nice dehumidifier, but, we're only talking less than a quart of water per hour at about 60% humidity.

Mineral buildup is definately something to think about, though, the air conditioner was free, so I don't have much to lose. I'm really curious to try out my laser thermometer and Kill-a-Watt meter to see what effect this has on a hot day.

But first I have to cut a hole through my concrete wall for the A/C.

I was looking at those big roll around swap coolers at Napa the other day, that would be NICE to have, even for outdoor work....but I was afraid to ask the price...

 

[Hades12]

I made my own version of these ten years ago to limp the old compressor on through "another" summer thinking that "next year" we might get an all-new A/C system. During July and August I ran the misters from 11:00 in the morning to 11:00 at night.

I could tell the difference when the misters were on and when I had forgotten to turn them on. No scientific data other then the house going from full roast to gentle boil.

Last spring we changed out the old system for a new Trane unit and have the compressor actuality cycling on and off during the day. What a concept!

I made mine out of Arizona Misters that came in pre-tapped 1/2" PVC couplers and 1/2" PVC pipe. I made a box out of the PVC pipe that I could remove from the A/C unit for servicing. Two misters on the top and two on the bottom spraying into the incoming air. The only downside I had was the water mixed with all the other junk floating around in the air made a hard crud that collected on the cooling fins. You need to take the covers of the compressor at least each spring and give it a good flush. Toward the end of summer it was a little swampy around the compressor but I planted mint for the ice tea to take advantage of the swamp.

Another thing I read is to weld a platform for the compressor which gets it up to around 18" off the ground. I read this keeps the grass clippings and other junk from collecting on the fins. Seems like a good idea for what is now required equipment living in the south.

At the hose bib I put a flow restrictor that you put on drip irrigation systems. It is like a hose washer but with a much smaller whole drilled into the disk and was rated at four gallons an hour. I put it where the hose attached to the hose bib. That way if the hose did burst I wasn’t going to pay for hundreds of gallons of water as I flooded the hood. 

During the summers my compressor ran all day so I didn't have to worry about the misters cycling on with the compressor. One of the links has a method of splicing into the A/C wiring but I could see a micro switch from Radio Shack and some sort of peddle that got blown up in the airflow that would make the connection. The electronics on this would exceed your material cost and would also buy a lot of water. Home Depot landscaping department carries a pack of drip irrigation restrictors and the different colors are for the different flow rates.

More info and one mentions of concern about mineral buildup on the coils if you have heavy water.

http://forum.beyond3d.com/archive/index.php/t-21760.html

http://www.marylandgreenpower.com/g...30-more-for-air-conditioning-than-businesses/

http://www.keepmaster.com/homeprojects/homeNew4.html

http://www.mistcooling.com/acprecool.html

http://www.coolnsave.com/

Nice thanks.

 

[Stuart in MN]

Depending on how much water you use, after a few billing cycles the landlord may change their mind on the free water clause in the rental agreement...

 

[Hlidskjalf]

You're going to rot out the condenser. Not necessary and the unit is not designed to run that way.

 

[AV8OR]

You're going to rot out the condenser. Not necessary and the unit is not designed to run that way.

I did this on an already old Trane unit and I didn't see any accelerated wear. The outside coil is made of copper tubing wrapped with aluminum fins. Both are fairly hardy materials when it comes to corrosion.

In my case I was just buying time for the inevitable replacement of the external compressor.

 

[pseudorealityx]

Any scale that develops on the coils will kill heat transfer in a hurry. Not talking "real" corrosion, but even a thin layer of scale will kill your heat transfer.

Also, the unit won't run as long, and therefore, it will do a poor job at dehumidifying the space. This may or may not be a concern based on geography. Southern Utah, not a big deal. Atlanta, GA... BIG deal.

 

[BioHazard]

Depending on how much water you use, after a few billing cycles the landlord may change their mind on the free water clause in the rental agreement...

She can change her mind all she wants, I've got a 3 year contract that says all the free water I can use! I already strongly dislike the landlord, so it's not uncommon for me to open up the hose full blast when I get there...only to let it drain back into the storm sewer and river where it came from.

Hell, if I could find a tanker cheap enough, I'd fill it up at the shop and use it for home water, too. Everybody's welcome to come by the shop for a heaping helping of free water.

I don't know for sure but I don't think our water has very many minerals in it. I know my water heater is a 1994 model and it's never been drained - not full of sediment either. I think if the water is allowed to flow constantly and not get hot on the coils then there shouldn't really be any scale buildup, more than there would be inside a copper water pipe.

This is all entirely experimental, I just need to wait for a hot day to play with it. Now I'm toying with the idea of making it entirely water cooled, that is, warm water down the drain, and no A/C unit sticking out of the wall.

 

[konnerbelly]

you have to have condenser, cooling tower, pump and piping system. Insvestment on water cooled condenser is higher.But chillers have better efficiency at lower temperatures of cooling water. So overall advantage, though water cooled system seems to consume more power, is for water cooled systems. Raw water cooled A/C heat exchangers should always drain back, and leave no salt water, to cause electrolosys, in the unit. This is the reason the pumps are not self-priming, and the installation drawings always ask for the unit to be at the highest point in the system to facilitate draining.

 

[redsky49]

It's somewhat fitting that Biohazard has posted this thread question.

Be aware that condensate from refrigeration equipment is typically laden with chemicals, such that the water is unfit for consumption, and is frequently corrosive. This is not the same water as produced from a distillation process.

If you are doing this simply for fun, or curiosity, and will accept an early failure of the equipment, and there is no downside to the increased water consumption, etc., etc., etc., this is what I would do:

Utilize an inexpensive garden timer that mounts on the hose bibb. You want operation only during occupied hours, and only during periods of the day that you can get the water to evaporate off the unit.

Create a spray situation that results in a fine mist that does not impinge on any electrical/electronic devices or components. Flooding the unit is not what you are aiming for, but just enough water to encourage some evaporative cooling of the critical components. If you have water flying about the unit you have introduced too much water.

Note that you could possibly flood the filter (creating a breeding ground for bacteria), or actually raise the interior humidity levels of the shop (by introducing water into the supply airstream), just to mention a few possible pitfalls with this idea.

As a rule, I don't approve of such experiments, particularly when mixing water and electricity, but if you are determined to go ahead, please do so safely.

Let us know what you discover.

as always, offered only as opinion

 

[Tom McDermott]

Commerical units use water cooling of the coil, but they are designed to avoid galvanic corrosion in the heat conduction joints. In a home unit there will be corrosion at the joints between the copper and the aluminum fins (dissimilar metals). With time that will degrade the heat transfer from the copper to the aluminum, and thus the efficiency of the unit.

For the short term, the water will improve the efficiency a lot. If the water is free and you don't care about long life for the air conditioner, then it will reduce electricity consumption.

-- Tom

 

[BioHazard]

I wanted to try this little project a few years ago with an old 5k BTU window unit I replaced. The old one was 10-15 years old and after I took it apart I could tell it had never, ever, ever been cleaned. The condenser was DISGUSTING, I can't believe it still worked, but it did. It was just ugly.

Unfortunately while taking it apart I knicked the refrigerant line...no more cold air from that one. So I turned it into an air compressor, makes 300 PSI in almost complete silence.

The cheap window unit I replaced it with just uses the hot side fan to splash any condesate water onto the coil. Seems like it just throws water everywhere randomly if it collects enough. In the summer I usually hose it down when I'm watering the plants, and it makes cooler air, but I've never done any more formal testing than that...

 

[Underdog]

She can change her mind all she wants, I've got a 3 year contract that says all the free water I can use! I already strongly dislike the landlord, so it's not uncommon for me to open up the hose full blast when I get there...only to let it drain back into the storm sewer and river where it came from.

Hell, if I could find a tanker cheap enough, I'd fill it up at the shop and use it for home water, too. Everybody's welcome to come by the shop for a heaping helping of free water.

I don't know for sure but I don't think our water has very many minerals in it. I know my water heater is a 1994 model and it's never been drained - not full of sediment either. I think if the water is allowed to flow constantly and not get hot on the coils then there shouldn't really be any scale buildup, more than there would be inside a copper water pipe.

This is all entirely experimental, I just need to wait for a hot day to play with it. Now I'm toying with the idea of making it entirely water cooled, that is, warm water down the drain, and no A/C unit sticking out of the wall.

Well then I'd open up a Laundromat in your shop.

 

[6768rogues]

BioHazard,

Before you spend too much time fooling with external water cooling, look closely at the unit you're acquiring.

I bought an 8000 btu unit a couple of years ago that has "internal" water cooling. The condensation water from inside goes to the outside of the unit, and then is blown through the outside coils by the fan that cools those coils. I can feel very slight water drops/spray when standing right by the unit. There is NO drip-drip-drip like on traditional units.

This is correct. Modern window units have a ring on the fan called a slinger ring. Condensate is slung onto the condenser coil to aid in cooling the coil and it reduces drips. That is the trick used to bump up the efficiency of newer units.

 

[MrMack]

Check this out, http://www.mistecology.com/
they are kind of expensive for me. I am thinking about using the Arizona mister kit and building a small metal roofed leanto shade over my outside Central A/C unit, and running the Arizona mister around the outside edge about every 12 inches I will have a mister nozzle. I have a water faucet within a couple of feet of the A/C unit and I was going to put a timer on the faucet to have the misters going from 2M til sundown. The arizona mister doesn't use a lot of water and there isn't enough water used to wet the ground.

I have used evaporitive coolers all my life. they circulate water up on the top of a fiber pad side with a small pump and as it runs down back, some evaporates, to the tank that has a float valve that uses a water line to keep the bottom of the cooler that acts as a reservoir filled. A big blower blows the cooled air out into the room. They work good if the Relative Humidity is low.

 

[FLACOMAN]

I was thinking of using a solar fountain pump for this purpose,since it floods the area around the a/c slab.

 

[tcianci]

"Be aware that condensate from refrigeration equipment is typically laden with chemicals, such that the water is unfit for consumption, and is frequently corrosive. This is not the same water as produced from a distillation process."

Please explain this.^^^ The water is CONDENSATE, do you know what that means? Where to the chemicals and the corrosiveness come from? Note that the evaporator coils and the condenser coils of a home AC unit are basically made of the same stuff and if the water condensing on the evaporator doesn't wreck the evaporator, why would it harm the condenser? I would argue that it is exactly the same as water produced from a distillation process.

 

[Stuart in MN]

Although water is used to assist with cooling, this technology is not related to the conventional Evaporative Air Coolers often called swamp coolers. Water is used to remove heat from the refrigerant and at the same time reduce the work of the compressor. The Water Cooled Evaporative Air Conditioner is a residential application of a technology already in use in commercial buildings for split system air conditioners known as chillers. Think of this technology as a mini-chiller for residential use.

reported as spam.

 

[Hmrhead]

As others have mentioned, the AC unit itself produces a fair amount of ice cold distilled water. Even though your water source is free you would do well to take advantage of the free cold water inside the unit to do the additional condenser cooling as it is is condensed from the air and therefore is mineral free.

Quick note: This water is NOT distilled!! Would highly discourage drinking of this water. This water is condensed, huge difference. The water comes in contact with many surfaces laden with trace chemicals from the unit as well as airborne contaminants(sp?). Keep the unit well drained and check often. Trapped water in AC units(commercial open water, roof mounted units) is where Legionaires grows.

 

[MikeLawrence]

Quick note: This water is NOT distilled!! Would highly discourage drinking of this water. This water is condensed, huge difference. The water comes in contact with many surfaces laden with trace chemicals from the unit as well as airborne contaminants(sp?). Keep the unit well drained and check often. Trapped water in AC units(commercial open water, roof mounted units) is where Legionaires grows.

Quoted for truth.

Going back to the original question, there is really no way I could ever see this being a good idea, well ever. It's not a matter of "could" it work or be efficient at the expense of shortening the life of the system, the answer is a resounding "of course it could".

The problem is that there are WAY too many ways to do it wrong in a way that doesn't involve hurting the machine but does involve the air coming out of it becoming... well, a biohazard.

Just my $0.02,
Michael Lawrence, LISSCO