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Swamp coolers work great and use a fraction of the electricity of an air conditioner in a dry climate with little humidity (like Phoenix) but there are downsides like mold and, well, everything feels wet in your house. Dry cool air is more comfortable than wet cool air.

Why don't the condenser units of a split system AC use water in some way to cool the condenser? Is it because the moist air would cause corrosion faster and the savings in electricity would be lost to the fact that you'd have to replace the unit? How do AC units in climates like Florida last more than a few years since it's humid all the time there?

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  • Great question. My condenser is below the level of the condensate drip line; I've often thought about letting it dribble down the outside of the condenser (it is outside after all, and in theory, waterproof).
    – TomG
    Sep 17, 2011 at 1:11
  • Stationary gas turbines sometimes use water spray into the intake to cool incoming air ( in hot dry locations like west TX .)
    – blacksmith37
    May 28, 2018 at 1:09

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Using a water cooled condensing units for refrigeration is not a new idea - large chiller units have been doing this for many years, but it's not as simple as hooking up a hose and letting er rip... there's a lot of additional maintenance involved with all the cooling water infrastructure - even a simple spray evaporation cooling system requires nozzle cleanings, pump maintenance and such pretty regularly.

Home AC units don't really need the efficiency boost from evaporative cooling because the air cooled condensing unit(s) are efficient enough without introducing the complexities of water lines, spray bars and a drainage system for a small direct expansion system. If the condenser is not giving you the proper heat rejection - just upsize the heat exchanger... far cheaper and more reliable right?

That being said, I have a window unit AC that takes the condensate and splashes it back on the condenser fins to boost efficiency, and I know there is a model of RV air conditioner which does the same thing. It is possible this feature has been added to DX condensing units - but I have been out of the HVAC world for some years now.

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  • The additional complexity does add maintenance issues but as long as a diy homeowner can do the work himself why not to save on the electric bill, right?
    – tooshel
    Aug 3, 2010 at 19:50
  • Any possible savings realized from the evaporative cooling will most likely be usurped by all the extra water you're using.
    – kkeilman
    Aug 4, 2010 at 4:46
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Looks like somebody makes a product that does exactly that.

Seems the problem with spraying water directly into the unit is increased corrosion as you mention. To get around that, it looks like their product actually uses a kind of "wet bag" that surrounds the unit and cools the air as it is sucked through the bag.

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  • Nice link! Never seen anything like it before but glad I'm not the only one thinking about it.
    – tooshel
    Aug 3, 2010 at 19:48

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