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Does evaporative cooling work?

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Forum topic by jcn posted 07-07-2010 07:22 PM 4054 views 0 times favorited 18 replies Add to Favorites Watch
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jcn

37 posts in 2401 days


07-07-2010 07:22 PM

My “workshop” is actually a detached 2 car garage. It has lots of space, which is very nice, but otherwise it’s a fairly rough situation. The walls are cinder block, which sit directly on concrete slab. No insulation. a few gaps have formed between the blocks. And on top of that, the garage door is not installed properly (previous owner) and does not close at the top. So, the garage is a heating and cooling nightmare.

With the current weather, I can’t really even do anything in the shop until it gets dark, and in the summer it stays daylight (and hot) until 8 or 9 o’clock. So I’m looking for a way to cool things down out there so I can get more done.

There are two windows, but for various reasons a window unit would be challenging. I’m looking at these free-standing evaporative air conditioners, and I’m interested, but skeptical.

Would an evaporative air conditioner be at all effective in an uninsulated concrete room, when it’s 97 degrees outside and 95% humidity?


18 replies so far

View HorizontalMike's profile

HorizontalMike

7152 posts in 2379 days


#1 posted 07-07-2010 07:38 PM

Not likely when your humidity is “95%”. Such coolers work best in dry environments because the air in dry places can hold more evaporating water. IMO, a traditional AC would be in order if your humidity is always that high, or nearly so.

-- HorizontalMike -- "Woodpeckers understand..."

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ajosephg

1878 posts in 3026 days


#2 posted 07-07-2010 07:41 PM

Sorry – evaporative coolers don’t work well in your part of the country – the humidity is way too high.

-- Joe

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KayBee

1083 posts in 2711 days


#3 posted 07-07-2010 07:50 PM

Swamp coolers work by adding humidity, air conditioners remove humidity from the air. If it’s already humid, it’s not going to work very well.

-- Karen - a little bit of stupid goes a long way

View TheDane's profile

TheDane

4997 posts in 3128 days


#4 posted 07-07-2010 07:59 PM

When I lived in Tucson, the swamp coolers worked fine about 46 weeks out of the year. Where I live now (Wisconsin), they just make it muggy and cold. I wouldn’t consider using evaporative cooling in a wood shop.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View SKFrog16's profile

SKFrog16

661 posts in 2665 days


#5 posted 07-07-2010 08:28 PM

Instead of a window, Just frame out an opening in the side of the garage and install the window unit in the new opening you’ll create. Insulate the inside of the roof and install two extra roof vents too.
Like TheDane says, Swamp coolers are only effective in areas where the humidity is low

-- Methods are many,Principles are few.Methods change often,Principles never do.

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jcn

37 posts in 2401 days


#6 posted 07-07-2010 08:35 PM

Yeah, I considered just knocking out a hole in the side of the garage for a window unit. But with my current budget and time constraints, it would be late fall before I got around to doing that, and by then I’ll be wanting a heater! Not to mention I don’t really know how or have the right tools to go cutting holes in cinder block walls.

I’m considering one of these portable AC units now. I could easily drill an exhaust hole in the front wall of the garage, it’s wood. But not enough open surface for a window. I see used ones on Craigslist for $200 or so.

Or maybe I should go ahead and buy a propane heater now while they’re cheap, and plan on getting a portable AC in the winter, when they’re cheap. And just sweat it out these next two and a half months.

Definitely not going with evaporative units though, thanks.

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TheDane

4997 posts in 3128 days


#7 posted 07-07-2010 08:41 PM

What about one of those heat pump units they hang out of the wall on hotels and motels. That way, you could have either cooling or heating.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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jcn

37 posts in 2401 days


#8 posted 07-07-2010 08:41 PM

Not familiar with those. Got a product link or something I can research?

View FaTToaD's profile

FaTToaD

393 posts in 2606 days


#9 posted 07-07-2010 09:19 PM

Everyone’s right who says it won’t work in that type of humidity. Out here in the desert, they don’t work well if the humidity gets above 18% – 20%. If a rain storm comes in at it gets above 30%, they are pretty much useless.

-- David

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TheDane

4997 posts in 3128 days


#10 posted 07-07-2010 09:37 PM

Something like this … http://www.amana-ptac.com/

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View SKFrog16's profile

SKFrog16

661 posts in 2665 days


#11 posted 07-07-2010 09:44 PM

Yeah, wait till fall. Rehang the overhead door, get your heater, insulate the roof, use low expansion foam in the cracks and find a masonry guy you can swap work with and have him make the hole in the wall for next years A/C unit.

-- Methods are many,Principles are few.Methods change often,Principles never do.

View Bill Davis's profile

Bill Davis

226 posts in 3389 days


#12 posted 07-07-2010 10:57 PM

In Phoenix, a relatively dry desert climate, where I spent the greater part of my life and where evaporative coolers were/are common, the radio weather reports regularly at least in the summer months provide an ‘evap cooler index’ which indicates the ability of the cooler to reduce the air temperature. It is, I believe, directly tied to the air’s relative humidity. If the RH is high then the output air temp of the cooler is higher. So that says the same as most here are saying – high RH reduces the ability of the evap cooler to reduce the ait temperature below the ambient temperature. It makes sense because an evap cooler reduces the air temperature by causing water in the cooler to evaporate. that process removes heat from the air. The ability to cause water to evaporate decreases with increased RH. You would still receive a benefit just from the moving air caused by the fan in the cooler, just not an additional benefit from the evaporating water.

Where my shop is located the temperature outside is 85 to 95 deg with a RH of 55 to 95 most of the year through. I can hardly work there more than a half hour unless I have a fan running. The fan does not significantly change the temperature in the shop but does make it comfortable enough to spend long hours working there. Before you go to too much expense on cooling try a good high volume fan. I have no temperature control and no RH control and no insulation. Wish I did but the fan alone did it for me.

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dbhost

5605 posts in 2697 days


#13 posted 07-07-2010 11:21 PM

Simply put. No.

Evaporative cooling, cools by adding moisture to the air(evaporating it), if your air is already moisture loaded and hot, you are only going to make things worse…

Now if you lived in Phoenix an evaporative cooler would be a dream come true…

-- My workshop blog can be found at http://daves-workshop.blogspot.com

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Moron

5032 posts in 3358 days


#14 posted 07-07-2010 11:35 PM

it would seem that you are SOL ?

-- "Good artists borrow, great artists steal”…..Picasso

View TheDane's profile

TheDane

4997 posts in 3128 days


#15 posted 07-08-2010 03:22 AM

I saw a workshop tour recently where the woodworker out two of those hotel/motel units in … can’t remember where I saw it (may have been here), but those things sound like a heck of an idea. A call to some local HVAC contractors might turn up some leads.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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