[Shop-talk] air conditioning misting system

[Steve Hammatt, Mount Vernon WA USA]

Jimmy
It’s more than increased corrosion due to dissimilar metals.
Distilled water is totally wrong due to another problem.  It’s 
highly aggressive (corrosive), especially to metals like aluminum.
Quick story:  I worked 27 years in industrial water treatment for 
boiler and mostly cooling towers.  Had a MAJOR chip manufacturer 
(not Intel) that switched water source for their 15 thousand tons of 
cooling water (one large cooling tower) over a weekend from normal 
water supply to plant reject RO water (very, very aggressive water due 
to almost no buffering minerals in the water) and by the time I got there 
to the customer’s site on Monday morning the entire tower and all the 
tower water was red with iron.  I don’t recall the pH, but it was quite 
acidic.  Carbonic acid..........the water picked up the carbon dioxide in the 
atmosphere and turned the no-long buffered water into carbonic acid.
That’s my story and I’m sticking to it.  I was there and I was the water 
treater.
Stories like this is what I used when training our reps.
Steve Hammatt


From: Jimmie Mayfield 
Sent: Friday, August 11, 2017 6:04 AM
To: shop-talk at autox.team.net 
Subject: Re: [Shop-talk] air conditioning misting system

I think I posted to this list 3-4 years ago about some of my experiments with this.  I was scheduled to have a new pair of heat pumps installed later that week so I wasn't concerned with ruining the coils.  When directly misting the coils, I recall measuring a ~30% drop in current drawn by the compressor.

I agree, though, that this is probably a bad idea long term.  At minimum, I'd expect scale to build up on the fins and that'll have a big effect on heat transfer.  But even if you're using distilled water, I'd expect to see increased corrosion where the aluminum fins contact the copper coils because you're subjecting those junctions to constant water (more so than normal condensation).



On 08/09/2017 04:32 PM, john niolon wrote:

  Anyone have any experience with the mister systems you install on your evaporator coil in your outside unit...   good, bad, waste of time.. or how many thousands of dollars and kilowatt hours have you saved... internet hype makes them sound like the best thing since they put pockets on shirts...

  john

   





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