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-   -   Install water mister by outdoor unit? (http://www.diychatroom.com/f17/install-water-mister-outdoor-unit-111638/)

slickwilliam 07-22-2011 02:39 PM

Install water mister by outdoor unit?
 
Our outdoor unit is on the east side of the house and is shaded in the afternoon, but the whole area is concrete, not lawn, and stays pretty warm even at night. More-so with the latest heatwave crap...

Enter hair-brained scheme...

I have seen water misters used to cool outdoor areas and was wondering if installing one on either side of the unit would lower the condenser air temperature enough to be worth the trouble? A couple of mister heads would use very little water and I would think (there I go again...) that dropping the temperature of the air flowing across the condenser might help.

Help some? No difference? Not worth the trouble?

I'd appreciate your thoughts...

Thanks...

Bill

PS: Oh, there's no problem with the unit - it's working fine. Just looking to optimize its operation...

biggles 07-22-2011 03:20 PM

try to keep the water off the unit just bearly hitting it just need to pre-cool the air the condensers is pulling in...couple of private hedges or pines will give the same result dripping water down them in the extreme hot days..and it's no hair brained :thumbsup: commercially with 105 read here with a heat index of 115 techs soak condensers down to keep them on line....

gregzoll 07-22-2011 03:21 PM

I would just go and paint the concrete something to cut down on the radiant heat. If it is shaded in the afternoon, I would not worry about it. Running water misters is a waste of money.

newtech 07-22-2011 03:37 PM

Cement and brick will hold the heat for a long time. I need to look it up, but if my memory is any good, I believe it is up to 2-3hrs, maybe even longer after the sun stops beating on it.

Misters will be cheaper than running the ac 24/7...

I have a chart that I will post when I can.


Newtech

slickwilliam 07-22-2011 04:30 PM

Thanks, all. I might give it a try with a temp install and see what happens.

I can go out at 10:00PM and the concrete is still toasty-warm, as are the bricks and everything else in the area. Back and front yards are all nice lawn and are noticeably cooler -- that's what got me thinking I might want to cool things off by the unit.

I figured about 4-5' away from the unit -- if it's getting wet, they're too close. With a temp install I can play a bit with the positioning. If it makes a big enough difference I'll perm it in.

Again, thanks...

PS: The whole side of the house is concreted. Next house over is up a 6' retaining wall. We used to have a major swamp over there every time it rained - Oklahoma clay soil doesn't drain well. Figured what the heck, just put concrete all the way from the front around the side to the back patio. Would be a -lot- of concrete to paint -- not just a slab around the AC...

zootjeff 07-22-2011 04:54 PM

In theory this does work. People warn about minerals in the water eating away at the coils. Some AC units actually pump the water from the indoor coil to a pool of water under the outdoor coil do do this very thing and benefit from the evap cooling. Every window based unit does this, so why not do it on your central AC unit?.. It does help some, if it's worth it or not is a judgment call. Here is a company that sells kits for this:

http://coolnsave.com/

tylerrussell 07-22-2011 05:23 PM

I tried this for a while....
 
....hooked up some misters a few feet from the unit outside (I'm in Michigan).
Monitored the air temperature readings inside from a vent close to the furnace. Temperature from the vent dropped 5 degrees with the misters running. Definitely made a difference inside. But I don't know the long term effect on the coil. Maybe if the water was filtered; or using the condensate water would be better; but my vent temperature dropped noticeably.

Mrdippy 07-22-2011 10:33 PM

I agree with the science of a mister helping heat transfer - it's genuine. If you have hard water you might get build up - if it's softenened water then it has a touch of salt which might corrode(?). I'm keeping the mister concept in mind for after my condenser hits the 10 yr mark.

beenthere 07-23-2011 07:37 AM

Quote:

Originally Posted by zootjeff (Post 691547)
In theory this does work. People warn about minerals in the water eating away at the coils. Some AC units actually pump the water from the indoor coil to a pool of water under the outdoor coil do do this very thing and benefit from the evap cooling. Every window based unit does this, so why not do it on your central AC unit?.. It does help some, if it's worth it or not is a judgment call. Here is a company that sells kits for this:

http://coolnsave.com/


While the condensate from an evap coil is dirty. It does not contain the minerals that water does from your faucet/house piping. So comparing the 2 is not an apples to apples comparison.

The coolnsave is not as great of a thing as many think. And quite a few people have paid for the damage their water has done to the condenser coil. In the way of either higher cost to clean the coil, higher electric bills as the extra minerals coat/closed off the air flow, or caused leaks.

They work ok in some areas, not in others, so people should be aware that they should regularly(weekly) inspect their condenser if they decide to use one of those misters.


For condensers set on large concrete areas. Simply keeping the concrete wet/damp will lower the air temp draw into the condenser, and leave n o deposits on the condenser.

mar0isa 07-23-2011 10:03 PM

Any idea if well water is better or worse than city water if used to cool the condenser? I was thinking of submerging a condenser in ground water supplied by my well in an attempt at a DIY experiment. I am replacing my unit in the next few weeks and planning to "play" with my old heat pump. Any suggestions?

Artco 07-23-2011 10:16 PM

If the system is sized correct for the loadand ambien for the location and the condensers are kept clean there should be no reason to spray water on the coil.
In all the years I have been in this trade the only time I ever saw water being sprayed was in an emergency situation (weekend not able to get parts) like a bad condenser fan or coils that were dirty and the owner was too cheap to maintain the equipment like they should.

beenthere 07-23-2011 10:24 PM

Well water can be worse then city water in some areas. Don't know the conditions of your water.

zootjeff 07-25-2011 12:07 PM

Quote:

Originally Posted by beenthere (Post 691862)
The coolnsave is not as great of a thing as many think. And quite a few people have paid for the damage their water has done to the condenser coil. In the way of either higher cost to clean the coil, higher electric bills as the extra minerals coat/closed off the air flow, or caused leaks.


I see they've added a water filter to their setups. Seems to me that if you have water soluble minerals, throwing a carbon filter at it isn't going to un-calcify and un-PH-ify your water. You can't all the sudden drink salt water because you run it through a carbon filter. Same thing here. You'd need a reverse osmosis or equiv..

Do you have any reason to believe their filter is actually going to condition water to remove minerals, or is it a marketing false advertising gimmick?

mar0isa 07-25-2011 12:27 PM

How do geothermal units use open loop systems without calcifing the coil? Is it protected by something? What about cooling towers. Do they have calcification problems? I know if your system is sized properly, you shoulder need to do this but its interesting if it drops your register temp.

Artco 07-25-2011 12:54 PM

Water towers are constantly treated with chemicals and there is a required bleed off to drain to help prevent scaling.
The tower requires a fan to cool the retun water for re-use.
Cooling towers have to be cleaned annually sometimes semi annually because of mineral build up.
In some cities the use of water unless aproved by the building department can be illegal for hvac use they consider it a waste of water.

I know of a large company that was using over 10,000 gallons of water a week and they were paying the water company for it. The State found out and fined them. They had to install a cooling tower system with the sump that was so large you could stack 4 box trailer side by side in it.

Why would anyone want to add a mister if their system was maintained and designed correct!!!


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