air conditioner pre cooler

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
User avatar
frhrwa
Posts: 898
Joined: Mon Feb 04, 2002 1:01 am
Location: Eastern Washington (state) and N. Las Vegas (winter)
Contact:

air conditioner pre cooler

Post by frhrwa » Mon May 07, 2007 9:10 pm

ok.. here goes... IF I take a swamp (evaporative) cooler and place it along side the a/c condenser unit.. using sheet metal, I box it in so the output of the swamp cooler blows the damp cool air into the vents of the condenser cooler... I use a 240vac relay tied to the contactor relay to sense when the fan motor on the condenser turns on, thus pulling the relay I've installed... I put a 120vac circuit on the contacts of this relay and run that to an on/off switch into the evaporative cooler... when the a/c comes on, the condenser fan turns on to cool the condenser coils, relay pulls, swamp cooler blows the cool air in lowering the temp of the air going into the condenser fan unit.... the condenser doesn't have to work so hard cooling, and when the air outside it 115 degrees like most cool days in Las Vegas, the evaportive unit should be able to lower this by 15 degrees or more... the a/c won't work so hard cooling the house, the compressor life is extended, and hopefully, the power bill will be less even using the evap. unit .... ? ? ? ? any thoughts :cool:

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Post by Chris Smith » Mon May 07, 2007 10:45 pm

In theory it sounds good?

What you have to remember about the swamp cooler is it doesn’t just blow cold winds, it relies on the evaporative effects of water landing on an object including wind, and then evaporating the heat away. [Removes heat through evaporation]

If the air has no escape, then it becomes just a hot swamp cooler, but if the air is allowed to expand and flow, it attracts the heat and then removes it from the area.

Placing a swamp cooler on the intake of a AC unit can back fire in several ways.

IF the air from the cooler is allowed to enter with the normal AC air, your defeating the purpose of the AC because it dehumidifies air, not saturate it.

The second failure you may have is if you just blow the watery wind over the evaporator, and it doesn’t flow correctly, it will simply turn the evaporator area into a “ hot swampâ€

User avatar
jwax
Posts: 2141
Joined: Mon Feb 09, 2004 1:01 am
Location: NY
Contact:

Post by jwax » Tue May 08, 2007 3:53 am

How about just dripping water over the intake fins?
Evaporative cooling for cheap.

User avatar
frhrwa
Posts: 898
Joined: Mon Feb 04, 2002 1:01 am
Location: Eastern Washington (state) and N. Las Vegas (winter)
Contact:

Post by frhrwa » Tue May 08, 2007 7:34 am

the a/c is actually in the attic, and the condensor fan is out back.. it has a large fan on top with an opening that exhausts the air that normally came through the sides to cool the gas... I just built a metal housing around the intake side of the unit and set the evaporative cooler up to blow into that box.. the pads get soaked, the fan in the swamp blows that cooled air into the intake sides of the a/c condensor cooler (and I'm sure the fan in the condensor sucks that air through also) where its fan exhausts out the top. When I turned off the condenser fan and used only the swamp cooler, it spun the condensor fan pretty good, so I know I'm getting cooled air into it when everything is fired up... also if the swamp fan quit, the condensor fan would just draw its air through the wet pads in the swamp cooler.. so its not sealed by any means.. none of this air goes into the house, its strictly for cooling the condensor unit.. :shock:

User avatar
Externet
Posts: 1785
Joined: Fri Feb 01, 2002 1:01 am
Location: Mideast USA
Contact:

Post by Externet » Tue May 08, 2007 7:48 am

As jwax says, the correct way to do it is by wetting the condenser (outside). And the most convenient way is using a fine water mist, as the used in outdoor cooling.
The evaporative cooler is a too convoluted way to do it, and will not improve things much. You want the condenser coils to be in contact with moisture absorbing heat by its evaporation.
if you search for something like condenser-water-mist-airconditioner; for sure some product should show up.
Miguel
- Abolish the deciBel ! -

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Post by Chris Smith » Tue May 08, 2007 8:40 am

All of this can be a waste if the AC is doing its job.

IF the condenser is having trouble then it could be assisted, but is that the problem?

A fine mist may sound fine but the technology to produce just a fine spray with out making a lake in the back yard involves very fine nozzles and a water filter to stop these tiny nozzles from blocking up.

A simple dip of a rotating filter, a drip and recycle, or complete sump pump and filter is much easier, but the whole swamp cooler Idea may be over kill that doesn’t work?

User avatar
frhrwa
Posts: 898
Joined: Mon Feb 04, 2002 1:01 am
Location: Eastern Washington (state) and N. Las Vegas (winter)
Contact:

Post by frhrwa » Tue May 08, 2007 9:32 am

in Las Vegas where the temps are over a 100degrees at midnight, anything helps... temps in the daytime of 119 are not uncommon, so blowing 119 degree air over hot coils doesn't work well, if you cool that air 10 to 15 degrees it would have to benefit somewhere along the process.?

and, that thought about the water mist isn't so bad, you could use the garden drip system with mist'rs, trigger the valve the same way using the relay on the contactor to turn it on and off with the a/c... then the condenser fan would just suck the fine mist right throught the condensor coils... hmmm... might try that one on another unit...

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Post by Chris Smith » Tue May 08, 2007 10:34 am

If you have the booklet on it it should show you the specs, and you can decide from there.

Im sure at the very least it will cause less strain on the whole system, but how much?

User avatar
haklesup
Posts: 2837
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Post by haklesup » Tue May 08, 2007 1:28 pm

Reducing the temperature of the air flowing through the hot coil of a split system should improve efficiency so long as precooling that air dosen't use additional energy OR reduce airflow through the condenser itself.

Wet air only has the disadvantage of possibly allowing mold to grow or increasing corrosion. These units are designed for outdoor operation. Corrosion should not become a problem. Regular maintenence should cover the rest.

Using a swamp cooler may decrese airflow so that's why a misting system is better. Other than that it should not tax the system. Under very humid conditions, either cooler may not do much, shading and positioning it in a natural draft is among the best things you can do. A misting head and a sprinkler valve plus a few pieces of PVC should do it. Nice thing about misters is that they have a large area where evaporation takes place without any large area to maintain (pads). Just mist into the air near the intake, don't really even need to spray the fins.

If sized and installed properly, the additional effort might not pay out much. A/Cs are already designed as efficiently for the installation as possible particularly if it is energy star rated. If it really helped a lot, it would be built into the unit from the start (like large commercial building air handlers)

If you have the means to measure the power used by the AC you will be able to see if it helped. Otherwise a few bucks in parts and time, it shouldn't make things worse (but it could depending on what you do)

User avatar
Externet
Posts: 1785
Joined: Fri Feb 01, 2002 1:01 am
Location: Mideast USA
Contact:

Post by Externet » Tue May 08, 2007 1:49 pm

Chris: The waste is not implementing the misting in a location that deserves it, as in LasVegas.
It costs pennies a nozzle. Buying it from a "specialized equipment" source will be much more. What you buy is a hole, a tiny hole.
Get a replacement nozzle at HomeDepot and fit a hose.

The misting is a REAL advantage and a huge $ saver for airconditioniong, no myth, no fancy "technology" and nothing new.

http://www.acmister.com/service/howto.asp

http://www.coolnsave.com/index.asp

http://www.rapidcool.net/fans.html?gcli ... YQodxAUowg

http://rapidcool.net/

The chance of mold growing is real as haklesup mentions, when the amount of mist is misdirected instead of hitting the condenser in amounts greater than the needed to produce instant flash evaporation.

And mold is removed fast spraying chlorine.

Miguel
- Abolish the deciBel ! -

User avatar
haklesup
Posts: 2837
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Post by haklesup » Tue May 08, 2007 2:10 pm

If you were concerned about nozzles clogging often, an automotive fuel filter after the sprinkler valve might be cheaper than a cartridge water filter installed before the valve.

I agree this would work particularly well in Las Vegas, the parts should be more available there as well since outdoor misting is epidemic in that city.

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Post by Chris Smith » Tue May 08, 2007 3:08 pm

What I have found from misting nozzles are the better they work, the more often they clog.

Hard water, soft water, almost all water contains calcium or even worse, iron.

The larger the nozzle size, the bigger the mess they make in the form of a swamp or lake?

If the AC unit can be helped by additional cooling on the evaporator, any one of several ways will help.

Design a drip or spray and recycle system of the fluids or else face a puddle in just a few hours. [good for the garden, but what a mess]

Place a filter unit near by and also recycle water through it like any swamp cooler. The swamp coolers fan can make up for any flow.

Run a rotary filter which runs through a water dip tray, and it also recycles and maintains the water level.

Or just spray small amounts of water on the condenser and watch the mess grow.

Having done the spray method for several experiments, the water mess quickly builds up.

On any super fine nozzle system, just incorporate a cheap water filter like the ones used for human drinking placed under the sink.

User avatar
jollyrgr
Posts: 1290
Joined: Thu Jan 03, 2002 1:01 am
Location: Northern Illinois
Contact:

Post by jollyrgr » Tue May 08, 2007 3:23 pm

An HVAC tech and instructor taught me this real neat trick for doing something like this. I have not needed to use it but it was one of those "what a great idea" things that has stuck with me going on 18 years now. He suggested using a wrap around cloth or evaporation pad, similar to the swamp cooler idea, to surround the AC condensor unit. That is straight forward. The "neat" part about his idea was to use a condensate pump (used to catch the condensed water that normally goes down the drain inside the house) to pump the water to a "drip" bucket outside by the condensor. Basically you take the water that comes off the evaporator inside the house and use that on your swamp cooler evaporation pads.

Here are examples of condensate pump. These are just for reference and I am not endorsing any of these:
http://www.filterace.com/SearchResult.a ... egoryID=28
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!

User avatar
dacflyer
Posts: 4310
Joined: Fri Feb 08, 2002 1:01 am
Location: USA / North Carolina / Fayetteville
Contact:

Post by dacflyer » Tue May 08, 2007 3:48 pm

i have a large window unit,,and i use fogger nozzels to keep it cooler running,,i actually use about 3-5 amps less power when the unit is cooled
then when it runs alone..and since i am using 2 fogger nozzels..i consume about 1/3 gallon of water an hr...
the unit i have is an old sears 18K BTU unit.. replaced the motor in it 3x since i have had it in the last 15 years,,no telling how old it was when i dragged it out of the dump...lol

once the motor quit,,and when i came home, the unit sounded like it was ready to blow up...the compressor was knocking/banging... i had to get up the courage to run in and turn it off, i was for sure it was toast..cause it was smoking some from the over heating..even the inside coils were like a oven at the time..once i turned it off, i let it cool for 3 hrs..then just for the heck of it, i turned it on for a moment to see if it was a goner ,, well belive it or not it was cooling..so i turned it back off,,got a replacement motor..and it still runs fine today..tough A/C if i ever saw one...

i just had to share that increadable story..;)

Gary
Posts: 66
Joined: Wed Dec 05, 2001 1:01 am
Location: Modesto, CA
Contact:

Post by Gary » Wed May 09, 2007 1:06 pm

While compressor coils are built for outside environment, and spraying water on them is a quick way of cooling them off in a hot dry envlronment, there can be problems.

Mineral and salt buildup on the coils from the evaporated water can be a problem. Also a problem is the combination of copper coils and aluminum fins in a wet warm environment that may contain salts or alkalis. The electrolytic corrosion from the dissimilar metals and the PH in the water causes the aluminum to be eaten away and deposited on the copper or vice versa. Sometimes called "white rust".

A good idea to reduce air conditioning costs, but not without hazard. And I don't think you want to pay the cost of distilled water to keep the coils cool.

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests