Swamp Coolers for garage cooling... your thoughts and advice much appreciated.

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You all know what a garage feels like here during the summer months. We have been thinking about getting one of the Evaporative Coolers for sale at Home Depot.

BUT, I don't know SQUAT about evaporative coolers/swamp coolers. Can they do a good job? What advice or suggestions can you offer regarding using swamp coolers in the garage?

Thank you.
 
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Swamp coolers will put out too much moisture that has to be dealt with. A ductless spilt system like a Mitsubishi, Daikin, LG, or Toshiba will cool (and heat) the space as needed, plus they’ll also dehydrate the humidity from the room.

(HVAC/R, boiler, and chiller mechanic ;))

Swamp cooler will rust your knives & guns fast
 
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Swamp coolers will put out too much moisture that has to be dealt with. A ductless spilt system like a Mitsubishi, Daikin, LG, or Toshiba will cool (and heat) the space as needed, plus they’ll also dehydrate the humidity from the room.

(HVAC/R, boiler, and chiller mechanic ;))
Thank you. I see, just to look for ductless mini split AC system. Which one would you go with for a 1000 sf garage that faces west?
 
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Find a unit that has good reviews. You size them according to square footage and insulation of the space. If your garage door is not insulated, I highly recommend doing that - otherwise that mini split will be running non stop during the day.

This article may help you with the sizing. Mitsubishi has been making mini split systems for many, many years (they are the ones who invented them way back in the 1950s). Another thing to consider is that if you park a hot car in the garage, the AC will be working very hard to overcome the vehicle heat. I would install some type of heat triggered exhaust fan to help pull the heat out (it would vent through your gable ends). And maybe someone who works in the AC industry will chime in with some guidance or corrections (if I have posted something that is incorrect).

 
Thank you. I see, just to look for ductless mini split AC system. Which one would you go with for a 1000 sf garage that faces west?

I’ve been a HVAC/R service tech/mechanic/installer for 30 years...


My favorite ductless split brand is Diakin, and I’d go with a heat pump instead of just straight cooling only equipment (yes, they make both) so your garage will be comfortable year round even if it gets nippy

If your garage is insulated figure about “1ton” (which is 12k btu/hr per “ton”) of cooling per 600-800 sq ft.... I’m in Oregon so we can get away with 800 sq ft, Arizona you better go with 600 sq ft to be safe. If your garage isn’t insulated you better figure 500 sq ft per ton .... so a 1.5-ton (18k btu/hr) to 2-ton (24k btu/hr) will do ya.... personally I’d go 2-ton.

The beautiful thing is going with the larger size unit, the cost difference is negligible and the cooling capacity ramps up and down to accommodate light and heavy cooling loads.



That’s my 10 cents, my two cents are free! ;)
 
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I’ve been a HVAC/R service tech/mechanic/installer for 30 years...


My favorite ductless split brand is Diakin, and I’d go with a heat pump instead of just straight cooling only equipment (yes, they make both) so your garage will be comfortable year round even if it gets nippy

If your garage is insulated figure about “1ton” (which is 12k btu/hr per “ton”) of cooling per 600-800 sq ft.... I’m in Oregon so we can get away with 800 sq ft, Arizona you better go with 600 sq ft to be safe. If your garage isn’t insulated you better figure 500 sq ft per ton .... so a 1.5-ton (18k btu/hr) to 2-ton (24k btu/hr) will do ya.... personally I’d go 2-ton.

The beautiful thing is going with the larger size unit, the cost difference is negligible and the cooling capacity ramps up and down to accommodate light and heavy cooling loads.



That’s my 10 cents, my two cents are free! ;)
Stomper... wonderful and very helpful comments to start me on my way with this project. THANK YOU. I was just about to buy a swamp cooler, and now glad that I didn't.
 
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Where I live the last rain was in April and we are not expecting another till Oct or Nov. The Humidity hovers between 12 an 20%. I cool my house with evap cooling. I have probably used the A/C a dozen times in 20 years. It's so dry here that I don't get rust problems. The cooler drops the air temp 7 to 14 degrees So if its 100 deg outside the inside temp stays around 85 or so. And adding a little humidity makes it more comfortable.
My garage is not well insulated, so it runs 10 deg less than the outside temp. 90 deg on a 100 degree day. without the cooler on a 100 deg day it would be 120 or so in there!
I keep tools, guns and reloading gear in the garage without any rust problems.

The big advantage to using evap cooling is the power usage is about 1/10 of the cost of A/C. That appeals to my cheap side! DR
 
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Where I live the last rain was in April and we are not expecting another till Oct or Nov. The Humidity hovers between 12 an 20%. I cool my house with evap cooling. I have probably used the A/C a dozen times in 20 years. It's so dry here that I don't get rust problems. The cooler drops the air temp 7 to 14 degrees So if its 100 deg outside the inside temp stays around 85 or so. And adding a little humidity makes it more comfortable.
My garage is not well insulated, so it runs 10 deg less than the outside temp. 90 deg on a 100 degree day. without the cooler on a 100 deg day it would be 120 or so in there!
I keep tools, guns and reloading gear in the garage without any rust problems.

The big advantage to using evap cooling is the power usage is about 1/10 of the cost of A/C. That appeals to my cheap side! DR
You raise a good point... here in the Phoenix/Scottsdale valley, the humidity is extremely low much of the time - except for a couple of days following the occasional rainfall.

My need to cool the garage would only be occasional - once in a while, for a day or two, perhaps, not regularly. The vast majority of days I would not be cooling the garage.

So... would a swamp cooler necessarily add too much moisture to a garage, when the ambient humidity is around 20%? Would tools in storage in the garage necessarily rust under these conditions when running a swamp cooler? (I don't keep any firearms or firearms related materials in the garage. Just misc. stored items and a few tool boxes.)
 
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in the 50 years in AZ (Tucson & Weaver Mtns) I have not had a problem with rust from "Swamp Coolers", only from de use. As a matter of fact I keep 1/2 a dozen water pots around the house to raise the humidity (indoor about 25 % when 10-12 percent outdoor) and lower the static electricity discharges. Some references say 40 -60 percent for human comfort, (not me, LOL)

That being said Both DHart and Stomper are right, for different locals and applications

When using a portable cooler in the garage cross ventilation is key, I used a high mount exhaust fan. Late July and August are tough, I find from sun rise to noon the best time to work in the garage. Once the DEW point (different from humidity) hits 55 % or it's 100 plus in the Phx metro area (10-10:30 am), swap coolers don't help much. And older r22 AC systems are taxed.

refrigerating a unsealed, insulated or not, garage is a waste of money, in my opinion, because of the 2nd law of Thermodynamics, heat travel from hot to cold. If you can't keep the heat out, then evap is your better bet, when humidity and dew points are low.

Therefore: Vent the garage, use 2500-3000 cfm cooler, wipe you tools down when done, clean and oil your guns once a year, (which you do anyway, right). And you'll be OK, you'll soon learn why 2pm is "siesta time" LOL Learn to work with what mother nature gives you. and you'll be happy 10.5 months of the year.

welcome to AZ, it may not be Hell in the summer, but you can see it from your roof! LOL!
 
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Once the DEW point (different from humidity) hits 55 % or it's 100 plus in the Phx metro area (10-10:30 am), swap coolers don't help much. And older r22 AC systems are taxed.

If you can't keep the heat out, then evap is your better bet, when humidity and dew points are low.
Steve... I'm a bit confused.

From what you're saying, then, if temps are around 100º outside, and let's say 20% humidity, (fairly typical day in summer around here) that a swamp cooler won't do me much good if I want to work in the garage that day?
 
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From what you're saying, then, if temps are around 100º outside, and let's say 20% humidity, (fairly typical day in summer around here) that a swamp cooler won't do me much good if I want to work in the garage that day?
[/QUOTE]

I understand, And its more a function of the dew point. I believe I miss typed earlier as the dew point is measured in degrees not % as I typed.

So as an Example earlier when I wrote the 1st post it was 98 deg. here with 20 % humidity outside and the dew point was 55 degrees outside and droping (now 46 deg). my coolest room was 78.8 and 30% hum indoor. But it felt sticky when I touched things. the humidity closer to the cooler was 51% @ 81deg (Yesterday it was only 25% indoors) So as per the conventional wisdom vis ve coolers 20 to 25 deg drop from outside temps is the norm. And My experience proves that out. See Chart attached

But with 110-115 temps in Tucson (summer) I would record 95 -98 degrees with 60% + humidity in late July and Aug Only 15-17 deg drop and high humidity. Hence the name "Swamp" cooler LOL

this can be made more comfortable by moving more air (high) and add a fan to keep the the air moving and cycling the pump so it "drys out " a little. I used a thermostat to do that.

to sum it up: DRY air low Dew point, 110 outside = 85 deg inside.
humidity rising, High dew point, 110 = 95 deg
you make the call

I don't know if were you live is new or older, but 1990 and new homes often have near floor level vents for carbon monoxide in the garage like my Parents home in the Northwest Valley. That's a heat source. AS is the garage door. Insulating it cuts the radiant heat but does not seal it against the ambient heat around the edges, See picture. It would not work very well if it was sealed.

Go out to the garage close the all doors with the lights out and you will see light coming in on all four edges. this is why it makes AC ineffective, because it works by recirculating the inside air. not by always adding more heat from outside. Just like your cars "recric" button function.

Also by comparison My electrical bill with Evap in May 2012 Tucson =$100 , June 2012 Phx North Valley with AC $480. Those are the closes data points I have. this is not a truly fair comparison because TEP & APS have different rates.
But I'm running about $98 for June here in the Mountians with APS. I'm also 12-15 degrees cooler the Phx metro. So take it for what its worth.

bottom line for swamp is you need to move the air every 2 minutes. IE 600 square foot Garage needs 2500-3000 cfm cooler AND Vented to the outside with a window or door cracked open about an inch or so. If you have a screen on your window you can put a piece of Toilet paper on the screen, with the window nearly closed. It will stay there because of air pressure. Then open the window until it falls off. Now close it halfway and that should be about right. That's a cheap air flow meter LOL

Good luck with your cooling project.

thumbnail_IMG_20200704_174704.jpg Air Apparent Temp.jpg
 
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You all know what a garage feels like here during the summer months. We have been thinking about getting one of the Evaporative Coolers for sale at Home Depot.

BUT, I don't know SQUAT about evaporative coolers/swamp coolers. Can they do a good job? What advice or suggestions can you offer regarding using swamp coolers in the garage?

Thank you.
I would recommend a window AC instead, they aren't very expensive and they de-humidify the air, which is a good thing if you have anything in your garage made from Iron or Steel. Even when the ambient humidity is low you are pumping moisture into your building, since you are cooling by evaporation. That evaporated water goes where the blower pushes it!
When I was a kid we had to use the swamp coolers because refrigeration was expensive and rare, especially if we rented and the swamp cooler is what was there. AC beats it hands down, save your money and shop for the better equipment, you won't be sorry. If you are renting the window AC is easily removed and transported to your next home. :cool::D
Remember I grew up in Tempe so I know a thing or 2 about cooling and HEAT! :rolleyes:
Gabby
 
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Our garage is large, about 1050 sq ft. with a high ceiling. The doors (10' wide and 18' wide) do provide a decent seal, but definitely not "air tight". The doors are labeled as "foamed plastic insulated" so perhaps there is a slight bit of insulation going on there.

There are no window options that an AC unit could be put into. The roof is a flat foam roof with high parapets all around it.

My working in the garage would only be occasional, so I don't need to keep it cooler in there all the time. Since the use would only be occasional, and the humidity is low here pretty much all the time (aside from a couple of days following the infrequent rain storm) perhaps the evaporative cooler would be a better and much less expensive way to go?

Would an evaporative cooler work well with outdoor temp of 100-105º, similar inside the garage temp, and humidity around 20%? (I have no idea about dew point.)
 

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