# Garage Air conditioner



## mwhatch (Jul 25, 2012)

I have a typical 2 car garage, about 22x22. Half is my work area and half is my wifes car. the door is insulated. I am thinking or getting a 12000 btu portable air conditioner to take the edge of the heat so I can work there in the evenings. I live in NE Oklahome. Does anyone have any experience with something like this.

Thanks
Morton


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## beck3906 (Jul 25, 2012)

Before we moved, I had installed a window in my 2-car garage so I could place an air conditioner in the window to keep the garage cool for me to work.  I only used a 5000 BTU unit because my wife was always concerned about the electricity costs. 

The garage was "comfortable" during the hottest days when I wanted to work.  The problem was getting the garage closed up so I could get the garage cooled.  The 5000 BTU unit took a long time to cool things.

One thing to remember is that each metal object in the garage is heated during the warming times.  Your air conditioner will need to cool down those metal objects to have the garage get to your working temperature.  My air conditioner was in the general area I wanted to work so it kept the immediate vicinty cooler.


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## LL Woodworks (Jul 25, 2012)

Although not a garage - I have a 12 x 16 barn style building  11 ft tall at the center that serves as my shop. It is insulated throughout - I put a 6500 btu window unit in it from Lowes and am very pleased.  Even in 100 degree days I can turn it on, come back in an hour or so and work very comfortable.


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## bluwolf (Jul 25, 2012)

Whenever I read these A/C threads I always have the same question that I've never gotten around to asking. Maybe it's been covered and I missed it. Is no one concerned about the temperature difference after the A/C is shut off?

As I understand it (and I could be wrong, that's why I'm asking) is that after you shut off the A/C it compounds the humidity problem and creates a condensation problem where you're tools are more prone to rusting. Here in SW Florida humidity is a big enough problem as it is. That's why I've never considered doing this even though I would love to.

Can someone clear this up for me?

Mike


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## TomW (Jul 25, 2012)

bluwolf said:


> Whenever I read these A/C threads I always have the same question that I've never gotten around to asking. Maybe it's been covered and I missed it. Is no one concerned about the temperature difference after the A/C is shut off?
> 
> As I understand it (and I could be wrong, that's why I'm asking) is that after you shut off the A/C it compounds the humidity problem and creates a condensation problem where you're tools are more prone to rusting. Here in SW Florida humidity is a big enough problem as it is. That's why I've never considered doing this even though I would love to.
> 
> ...



I'll take a shot... The A/C removes water as it cools the air in the condenser.  That lowers the humidity of the air in the room.  WHen you shut the A/c off, the air in the room will eventually return to whatever state the air was without the A/c.  The A/C will not "create" humidity, and it is quite unlikely you will get the room cold enough for condensation during the period that warmer air is introduced back into the room.  I have an a/c in a former garage, where I put in a wall to replace the overhead door.  Live in North Texas where  it gets pretty hot and humid, but not "new orleans esk"

Tom


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## edstreet (Jul 25, 2012)

2 base types of ac units, ones that reduces humidity and ones that does not.


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## TomW (Jul 25, 2012)

edstreet said:


> 2 base types of ac units, ones that reduces humidity and ones that does not.



I was talking about an Air Conditioner, which circulates Freon, not a "swamp cooler" which evaporates water into the air.  I would never use a swamp cooler in my shop...


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## lsweeney (Jul 25, 2012)

*Air in Garage*

You may think about dividing the garage in half , car on one side, shop on the other, I used a plastic curtain hung from a wire down the middle of the garage. Also if you wife's car is hot, like driven in the last couple of hours, back it out of the garage ,before you turn the air on......


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## holmqer (Jul 25, 2012)

There is a lot you can do to help control garage temperatures.

Insulate well to reduce heat rise in the summer and retain heat in the winter

Keep cars outdoors after driving them so that the engine cools off. When I get home from work I leave car outside until dusk then move it into garage.

Open the garage early in the morning when it is still cool, and run a fan to blow cool air inside. The inside air will drop fairly quickly, but keeping the fan on will draw heat from the interior structure which will help to reduce heat rise during the day.

Keep garage door closed when not absolutely necessary to be open

With these tricks, despite the extended heat waves of 90F+ for days on end, my garage has only hit 80F once. It is typically 75F when  get home from work which is reasonably comfortable to work in. I have no air conditioner.

I've been tempted to get a small AC for humidity control as most de-humidifiers generate some heat and I don't need a heat source this time of year. The humidity has been 70% plus for weeks.


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## eldee (Jul 25, 2012)

I have used a portable unit in two garages (both insulated) with pretty good luck. With my current arrangement, I have an industrial curtain from ceiling to floor that cuts the space down to one bay. It cools off pretty quickly and stays comfortable. I would avoid a long vent hose, if possible, as the hot air travels through it and counters the cooling a bit. It you're able to keep the air flow in your direction, you can probably use the space pretty quickly. The sun falls directly on my door late in the afternoon, and opening it isn't a good option. With the curtain, opening the other door briefly has little impact.


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## EricJS (Jul 25, 2012)

bluwolf said:


> Whenever I read these A/C threads I always have the same question that I've never gotten around to asking. Maybe it's been covered and I missed it. Is no one concerned about the temperature difference after the A/C is shut off?
> 
> As I understand it (and I could be wrong, that's why I'm asking) is that after you shut off the A/C it compounds the humidity problem and creates a condensation problem where you're tools are more prone to rusting. Here in SW Florida humidity is a big enough problem as it is. That's why I've never considered doing this even though I would love to.
> 
> ...


 
Mike, the AC shouldn't compound the humidity problem. The phenomenon you are talking about will only occur when your tools reach very cold temperatures. If your tools are 30-40 degrees and are suddenly exposed to high humidity, then yes, the tools will sweat (such as a glass of ice water on a hot humid day.) The tools won't get that cool with an AC, and they will warm up quickly after the AC is turned off.

Humidity is the by-product of some heating systems, so this can be an issue in the winter for some shop owners, as their tools may be exposed to freezing temps when the heaters are "fired up" in the morning.

Hope this helps.


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## holmqer (Jul 26, 2012)

bluwolf said:


> Whenever I read these A/C threads I always have the same question that I've never gotten around to asking. Maybe it's been covered and I missed it. Is no one concerned about the temperature difference after the A/C is shut off?
> 
> As I understand it (and I could be wrong, that's why I'm asking) is that after you shut off the A/C it compounds the humidity problem and creates a condensation problem where you're tools are more prone to rusting. Here in SW Florida humidity is a big enough problem as it is. That's why I've never considered doing this even though I would love to.
> 
> ...



Right now, at my home the Dew Point is 64F, if I got my tools down to 63F and wheeled them outside, moisture would form on them. If I ran an AC in my garage and got it to 63F and let the tools reach thermal equilibrium, the dehumidification of running the AC would reduce the Dew Point in the garage to a lower point. As long as I left the garage closed up, the temperature and humidity would rise gradually and the tools would stay above the dew point. The reality is that I would be very unlikely to get my tools below the external dew point with an AC


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## bluwolf (Jul 26, 2012)

TomW said:


> I'll take a shot... The A/C removes water as it cools the air in the condenser. That lowers the humidity of the air in the room. WHen you shut the A/c off, the air in the room will eventually return to whatever state the air was without the A/c. The A/C will not "create" humidity, and it is quite unlikely you will get the room cold enough for condensation during the period that warmer air is introduced back into the room. I have an a/c in a former garage, where I put in a wall to replace the overhead door. Live in North Texas where it gets pretty hot and humid, but not "new orleans esk"
> 
> Tom


 


EricJS said:


> Mike, the AC shouldn't compound the humidity problem. The phenomenon you are talking about will only occur when your tools reach very cold temperatures. If your tools are 30-40 degrees and are suddenly exposed to high humidity, then yes, the tools will sweat (such as a glass of ice water on a hot humid day.) The tools won't get that cool with an AC, and they will warm up quickly after the AC is turned off.
> 
> Humidity is the by-product of some heating systems, so this can be an issue in the winter for some shop owners, as their tools may be exposed to freezing temps when the heaters are "fired up" in the morning.
> 
> Hope this helps.


 
Tom and Eric,

Thank you, yes that helps. I remember a thread on another metalworking forum where they were arguing about it. But it went on for so long w/o coming to a point, that I gave up on it. It was just a couple of the points that stuck in my head without context. I appreciate it.

Mike


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## ironman123 (Jul 26, 2012)

I like LL Woodworks have a 12X16 insulated shop and have a 12,000BTU air conditioner that provides adaquate cooling on 100+ days.  I also live in Texas.

Ray


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## TomW (Jul 26, 2012)

I forgot to mention my shop AC....I dont know exactly how many BTUs, but I know it has enough BTUs to heat a BUTT as big as a TUB.....
Tom


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## Wood Butcher (Jul 26, 2012)

Just start up her car, turn on the AC in it to max and leave the car doors open; that's red neck methodology.  Seriously, I have considered a "window" or through the wall unit but am concerned that I will spend more time cleaning saw dust from the unit than woodworking.  I am considering having a heating/cooling expert figure out if a duct could be added to the house system without straining the system and venting to the shop.  I don't need to keep fresh meat in the shop (it's heavily insulated) just maintain a comfort level for an old man.
WB


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## beck3906 (Jul 26, 2012)

I have a room with a duct running into it as you described.  While cool air enters the room, lack of a return air duct for the a/c system to exchange the air makes this very inefficient.


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## AnachitlPut (Jul 26, 2012)

we have about the same space but we jusy put in a window unit works like a charm in 100+ weather


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## Sataro (Jul 26, 2012)

A/C sounds nice. Here is Central Texas that heat does get warm... My shop is a 14 x 24 shed. No insulation... getting to the point that I'm seeing some daylight between the walls. Definately in sad need of some major repairs... I've got an old A/C blower fan pushing air on me, a small Stanley work fan blowing on me from another side, & a small box fan stuck in another window pointing at me from a 3rd side. Not nice like an A/C but I'm surviving. Of course, if it gets too hot... I just quit & go jump in the pool.


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## PTsideshow (Jul 28, 2012)

You might think about the portable type ones were the hot air is exhausted out a 4 foot hose to the outside. you can use a window with the vent end it or a dry type wall vent.  The instructions for all most all units state that the exhaust hoses should be no longer than 4 foot. I'm thinking of one. For the second floor instead of the window unit as it is easier to put in and take out. Wife prefers the window open, with the portable you can remove the vent piece easily.
The nice thing about them is you can point and shoot the air in a better direction, than the fixed window unit.
The A/C company that just replaced the A/C furnace in my parents house uses them for customers during removal, insulation and during the couple of days before the new one is in.
Home Despot and Highes have them and the info on line.
:clown:


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## DSurette (Jul 28, 2012)

One downfall of the single hose portable ACs is that the air being exhausted has to come into the room somehow or the AC will be very inefficient.  We have a dual hose 12.5K BTU that we are very pleased with.  There was a discussion about this a few months ago.


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## RetiredJake (Jul 28, 2012)

I have a 24 x 24 garage. I fully insulated it last year, including the door. I then installed a window AC through the wall in one corner. I have mounted 2 fans to the ceiling that circulate the air around the shop in the same direction as the AC. One of the fans has a filter mounted on it, and is usually only run when the tablesaw or router is in use to keep the dust down. I have to vacuum the AC filter and grill work about every 7 to 10 days. The AC unit is 10,000 BTU'sand has kept the shop cool through our 100° plus weather this month. But you have to keep it running, if you let the shop get hot, it has a heck of a ,time cooling the structure back down.


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## plantman (Jul 31, 2012)

:tongue::tongue:  One of the principle ways to feel cooler in hot or humid conditions, is to have air movement. Even if you have 100 degree air blowing over your body it will make you feel cooler because the moving air wicks the moisture away from your body. If you place one or two fans in a manner so that they will circulate the air around your room, it will feel much cooler. Add to this an AC unit, and you will be as happy as a mouse backing into Pussywillow. When you go to buy an AC unit, first measure the square feet of your space. Most stores will have a chart that will tell you how big of a unit it will take to cool that area. If you go over that size, you will be able to cool your area faster and the AC will recover much quicker and run less. I think that a 12000 btu AC is the largest unit can buy that will plug into a 120 volt outlet and reguires a 20 Amp breaker with #12 wire. Look on the ID plate on the unit, it will give you the requirement needed for that unit. A note on the roll around units. They come with a drain hose that needs to be delt with. Keep your head cool, and your drink of choice colder.         Jim S


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## Tom T (Jul 31, 2012)

Morton,
I do a/c for a living in Florida.  I can get really in depth on what to do.  But who wants to read a book.
If the garage is insulated okay. 400 square foot per ton (12,000 btu per ton)will work, a little bigger unit will cool it faster. ( For those who do a/c this is not really the way to do it, you would run a heating  cooling load.) 
This should work for you as some one else said watch the breaker size.

Filtration is your worst issue.  Dust we generate when we work will plug it up big time.

What I did at my home is put a 1 & 1/2 ton split system with a 5 inch meda filter in it.  I aLso put a pre filter in 20/20 it is changed often and the media filter is changed 2 times per year.

For a window type unit try and rig up some kind of filter on the return the trick is you are no allowed to restrict the air, so a bigger box has to be made to increase the filter area which is very hard to do on a window unit.  Do not blow the cool air directly on any tool at close range or it will condensate and rust.  I live in central Florida and everything wants to rust any way.  
Hope this helps.
Tom


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## moke (Jul 31, 2012)

Morton..
I have been and am still going through this right now. My shop is a little bigger than yours --it is about 800 square feet--I have two portable a/c units both 12,000 btu. I have successfully cooled the shop to about 5 degrees cooler than the outdoors. I was and am frustrated to say the least. My shop while fully insulated just never seems to get cool. I had a friend over and we noticed on one of the 100 degree days that in my attic, was 126 degrees, I measured it with a meat thermometer....I have very dark shingles, and while I have a ridge vent and soffit vents, the soffits are covered with insulation. It is literally like an oven right on top of my shop. Right now it is too hot to go up there and fix it, so I am waiting for cooler weather. If I were you I would make sure you have a vent fan or something in your attic before you start. Those a/c units are working as hard as they can and just not making any headway, becasue the air filtration unit is 6 inches from the ceiling and with the dc unit it is just grabbing the warm air from above your head and defeating the a/c. I am certainly no expert, so this is just my .02


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## plantman (Aug 1, 2012)

*cooled attic*




moke said:


> Morton..
> I have been and am still going through this right now. My shop is a little bigger than yours --it is about 800 square feet--I have two portable a/c units both 12,000 btu. I have successfully cooled the shop to about 5 degrees cooler than the outdoors. I was and am frustrated to say the least. My shop while fully insulated just never seems to get cool. I had a friend over and we noticed on one of the 100 degree days that in my attic, was 126 degrees, I measured it with a meat thermometer....I have very dark shingles, and while I have a ridge vent and soffit vents, the soffits are covered with insulation. It is literally like an oven right on top of my shop. Right now it is too hot to go up there and fix it, so I am waiting for cooler weather. If I were you I would make sure you have a vent fan or something in your attic before you start. Those a/c units are working as hard as they can and just not making any headway, becasue the air filtration unit is 6 inches from the ceiling and with the dc unit it is just grabbing the warm air from above your head and defeating the a/c. I am certainly no expert, so this is just my .02


 
 Mike: As long as you are going up in the attic at some point to open up your soffit vents, you might want to try this also. If you don't already have them installed, go to your big box store and purchase the styrofoam vent panels that fit between your roof rafters. These bring cooler air into your attic and increase air flow to your ridge vent, as well as keeping your soffit vent clear. You may also want to look into a solar powered roof fan that requires no wiring and only runs when a set temp. is reached. This forces air flow instead of relying on convection to do the job. I think these are also made to fit in the peaks on the side of your house if you don't want to cut a hole in your roof. Also adding extra insulation over your work area will keep the heat from moving down.  Jim S


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## moke (Aug 2, 2012)

Thank you Plantman...I will do it!!


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## penhead (Aug 2, 2012)

Well, I have a 24' x 24' shop, and using a 10K BTU window unit and two fans have manage to keep the shop temp to a comfortable working enviorment this summer with temps usually in the 90+ range and the humidity just freakin' high...the A/C makes the cool air and I have the fans positioned to circulate the cool air...must note the key to comfortable is 'good insulation'..!!..

Humidity is well controlled in the shop, but it's a real bear when you walk outside ;(


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## JohnLifer (Aug 4, 2012)

I'm over in NW Arkansas.  I put in a 6500K window unit from Lowes a couple of months ago.  It does a pretty good job of cooling the garage.  It won't get it down to 70 when it is 105 outside like the past few weeks, but with a fan running, it is mid to lower 80s and that is comfortable to me.  If you can afford, I'd go with a 10-12K unit, it will cool faster and more consistently.


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