Air conditioning / Heating in Garage

[scotstern]

Does anyone have any experience with split air conditioners in a garage. I have a three car garage so I think that it would need a 2 ton unit. If you do, what kind, what size and how much amperage?

Thanks,

Scot

 

[TheShrine]

I put 2 split systems, 18K Toshiba Inverter units, in The Shrine. They cool and heat just fine until you open one of the garage doors. It's not the unit's fault....it's the application. I find myself sitting under one of the units as it blows directly on me during hot days. The heater is more reasonable during the winter because the doors stay closed. And, yes, windows = double insulated pane, garage doors = insulated and entire structure is insulated.

Knowing what I know now.....I would have spent my money more wisely/differently.

 

[pmiranda]

Knowing what I know now.....I would have spent my money more wisely/differently.

You can't leave us hanging like that. What would you have done differently? My first thought is to separate the work space that you want cooled from the storage space that you won't be spending as much time in, or would you have gone with a different system?

 

[NUTTSGT]

I moved this to the Heating and A/C section of the forum. It should get more traffic here.

 

[Mystic_Cobra]

I'm considering heat and AC for my garage makeover. I was thinking a gas shop-type heater (have gas line in the garage) and a mini-split but that seems wasteful. I'm going to be replacing my home AC/furnace soon, would it be less costly to get a condenser that can handle two air handlers (one for house, one for garage)?

 

[JakeKohl]

Your mini-split advice sounds like it was derived from an under powered installation (or in your location with extreme temps...which would be tough to heat with any heat-pump system). I have a 24x36' garage that my 18kbtu mini-split can drop the temp from 90 to 74 in less than 10 minutes. I think they're incredible and installed one in my 2nd floor office over the garage as well. At 22 seer, I have barely seen a bump in my utility costs (~$30/mo) cooling the 2nd floor full time and the garage about 1/3 of the time...that's 1,700 square feet of living space heated and cooled. The outdoor units are also exceptionally quiet.

My garage split (18kbtu) required a 25amp 220V service. As I mentioned, my space is 24'x36'. It is also well insulated with insulated garage doors. My initial calculations indicated that 12kbtu would handle the space with about 5-10% to spare for cooling but it would be under powered if I wanted to heat the space to 68 degrees in the winter. I installed an 18kbtu unit and it doesn't work very hard. I'm in upstate South Carolina - the summer is hot but the winters are fairly mild. Your local weather will probably be slightly easier on the energy demand.

 

[Falcon67]

I'm cooling 960 sq/ft with 17,000 BTU in two window units. I heat the space with about the same from a single 240V heater unit. My 1st choice with money no object would be a mini-split. Second would be a 24K take out unit from some bitty house reno project. My 3rd choice is what I have right now.

 

[pseudorealityx]

I passed on the splits for a number of reasons, none of them popular with those who installed splits.

If you're going to maintain the same temp no matter if you're in the garage or not, insulation and a split will work most of the time, until you open that door and it has to play 'catch up' for the next couple of hours.

My central air sits on the roof not taking up a foot print or hanging outside a wall.
It has registers well placed around the room and an air pick up far from any of them.

My 4ton unit cools my two car AZ garages from 85 or so to 75 in mere minutes, maybe 15. If I open the door on a 115 degree day, it catches back up in maybe 5 minutes. Split guys claim the same from their smaller units with a fan 1/4 the size...maybe they are right.

Air dispersal is from everywhere, not a fan blowing in one direction from the side of the wall.

Heat is evenly distributed as well.

We will be putting a split in the wifes sewing room as it is the farthest vent from 'real life' and the room gets pretty hot with her lighting and machines. It's a 12x13 roomso a split is the answer. Just telling you this so you don't think my roof mounts might be a religious choice of some sort. They are fine booster units.

I have five roof mount a/c units and about to install a sixth. If a split had been any value in a garage other than as a 'booster' I'd sure have them instead.

split guys will be here soon to counter....

I know this wasn't your question, just thought you might want to know. I live in AZ and have extremes from 10 below zero to 100 at one garage and 40 to 126 [that's 170 on the roof] at the other. My decision was based on extremes, not averages.

This is the same 'story' you keep posting, and it STILL doesn't make any sense.

ANY HVAC unit has a rated capacity, and it can perform THAT rated capacity. Whether or not you separate the compressor from the evaporator (split system) or you put into 1 box (packaged unit), DOES NOT MATTER as long as they're installed properly. One does not cool "faster" than the other... that's just silly.

 

[dbonne]

I just put a 4 ton split unit in my 60 x 40. Without any insulation in the attic, I could cool it off (drop the temp 40 degrees) in an hour with outside temp of 100. With insulation, I can do the same in 25 minutes. Of course that is with nothing in the shop.

Remember that a BTU is one degree per pound (of load), One ton (referigeration) is the ability of the unit to produce 2000 pounds of ice in 24 hours. If you have an 12Kbtu unit, that is really 12000 btu/hour or one ton. Let's say that I had 10,000 pounds of contents in my shop that I had to cool 40 degrees that would be 400,000 BTU's. I have 4 tons of cooling capacity, that would be 48,000 BTU's per hour. It would take 8.3 hours to pull that down 40 degrees.

No matter what unit you use, a BTU is a BTU (what you said, pseudo). Contents and heat loss are the determining factor of how long it will take to get temp down. I

 

[pseudorealityx]

I just put a 4 ton split unit in my 60 x 40. Without any insulation in the attic, I could cool it off (drop the temp 40 degrees) in an hour with outside temp of 100. With insulation, I can do the same in 25 minutes. Of course that is with nothing in the shop.

Remember that a BTU is one degree per pound (of load), One ton (referigeration) is the ability of the unit to produce 2000 pounds of ice in 24 hours. If you have an 12Kbtu unit, that is really 12000 btu/hour or one ton. Let's say that I had 10,000 pounds of contents in my shop that I had to cool 40 degrees that would be 400,000 BTU's. I have 4 tons of cooling capacity, that would be 48,000 BTU's per hour. It would take 8.3 hours to pull that down 40 degrees.

No matter what unit you use, a BTU is a BTU (what you said, pseudo). Contents and heat loss are the determining factor of how long it will take to get temp down. I

BTU is the energy to raise 1 pound of WATER 1 degree at 1 atmosphere of pressure.

1 ton of cooling is 12,000 btu, and it equivalent to the heat of fusion for 2000 lbs of ice in 24 hours. It's taking 2000 lbs of water at 32 degrees, and making it into 2000 lbs of ice at 32 degrees.

Some materials heat conduct energy better than others, and others have more thermal mass than others, so you can't directly compare a pile of 500 lbs of wood to a pile of 500 lbs of metal.

 

[dbonne]

Hey Pseudo, thanks for clarifying my post. I guess I was a little vague.

Ducksface, you are correct in the even distribution of air over the area being referigerated is superior to having one outlet seperated by 6 inches from the inlet!

 

[pseudorealityx]

But I think you could take the heat sink value and divide by the number of cooling sources/ducts.


There are multiple ducts in my car for a reason. There are multiple ducts in my garage for a reason. I have to draw the heat from cabinets 25 feet from other heat gatherers.

You realize there are split systems outside of the mini-split stuff seen on here so much, right?

Commercial split systems are the same as a packaged unit, except in 2 pieces, with an air handler inside, and typically ducted, and then a remotely located condensing unit housing the compressor and condenser coil.

 

[hippie2cams]

I just installed a 3.5 ton heat pump in my 30x40 with a 16x8 door in front and an 8x8 door offset in the rear to naturally draw air through garage in early mornings but when the hot texas sun heated the building in the middle of the day it would get to 100 inside. yesterday afternoon at 3:00pm it was 74 degrees inside with all doors shut so I'm calling it good. At least it's good enough for me and I'm the one who spent the money.

 

[pseudorealityx]

Yes, I have one on the Williams house.
I'm all but certain that NO ONE here ever means to use those when they say split.

If they did, there would be no questions, just three bids and done.

The ONLY reason I don't have that commercial split on the garages/houses:
Ground space is at a premium. Roof mounts allow me rv and boat parking close to the house with power and water and sewage.
I'd need six feet from the house if a ground unit, times a 30' boat, compounded by a space only 10' wide...ground unit equals no side parking at two of the garages. That is the only reason.

Minis are as described above. If you love uour mini, plug all but one outlet in your car and then get back to me about how satisfied you are.

Seems clear to me that folks say 'mini-split' when they're talking about those...

 

[JakeKohl]

I just put a 4 ton split unit in my 60 x 40. Without any insulation in the attic, I could cool it off (drop the temp 40 degrees) in an hour with outside temp of 100. With insulation, I can do the same in 25 minutes. Of course that is with nothing in the shop.

Remember that a BTU is one degree per pound (of load), One ton (referigeration) is the ability of the unit to produce 2000 pounds of ice in 24 hours. If you have an 12Kbtu unit, that is really 12000 btu/hour or one ton. Let's say that I had 10,000 pounds of contents in my shop that I had to cool 40 degrees that would be 400,000 BTU's. I have 4 tons of cooling capacity, that would be 48,000 BTU's per hour. It would take 8.3 hours to pull that down 40 degrees.

No matter what unit you use, a BTU is a BTU (what you said, pseudo). Contents and heat loss are the determining factor of how long it will take to get temp down. I

While it may take some time to bring heavy metal objects to the conditioned room temperature, those objects are not going to keep the air from reaching that temperature rather quickly. They do have an effect but it's exceptionally small - it's not hardly worth worrying about. You experience the air temperature so even though the wall may be 84 degrees, if the air is 74 degrees, you're pretty comfortable.

 

[Chris05gto]

I went with a 2 ton Mr. Slim for my 26' x 28' garage.... it works good.

 

[Falcon67]

High 5 to hippy2cams on that Texas heat thing. I left out that my building is R13 walls and ceiling with a regular 7x16 door that has 1/2" foam insulation panels stuck to it. The west wall is 24' wide with a gable and gets to 130F+ on the surface. I set the timer on the "window splits" to come on at 4PM today. Ambient outside was 95F, inside it was 82 in the big room (10.5K BTU unit, 24x28 area) and 79 in the 12x24 work area (6.5K BTU unit).

 

[guildan101]

I purchased a used 8k btu portable ac that Igot from craigs list for $140 to provide cooling in my one car garage here in the humid south carolina heat. The garage door needed to be replace so i went with a triple insulated one from presion door installed for $1000 (9 R value rated). The garage itself was already decently insulated with no windows so i just added some caulk where ever i saw it needed it. I hired an electrician to run me a 20amp outlet (only had one on the other side of garage prior to installation). He also installed a dryer vent outlet to properly vent out the hot air. This way if my used portable ac goes bad I can easily put in a replacement one. The electrician also ran a clear watertline tube that connects to the drip valve of the portable unit and just drips water out in my driveway outside so i dont have to worry about changing or dumping out the resevoir. So far with 95 degree heat and 85% humity that small portable ac keeps my garage at 76 degrees and 35% humity with no problems. The ac costs about 80 cents a day to run 24/7 but I will only run it when me and my wife work in there or if we keep our dogs in there during the day.

 

[pseudorealityx]

I purchased a used 8k btu portable ac that Igot from craigs list for $140 to provide cooling in my one car garage here in the humid south carolina heat. The garage door needed to be replace so i went with a triple insulated one from presion door installed for $1000 (9 R value rated). The garage itself was already decently insulated with no windows so i just added some caulk where ever i saw it needed it. I hired an electrician to run me a 20amp outlet (only had one on the other side of garage prior to installation). He also installed a dryer vent outlet to properly vent out the hot air. This way if my used portable ac goes bad I can easily put in a replacement one. The electrician also ran a clear watertline tube that connects to the drip valve of the portable unit and just drips water out in my driveway outside so i dont have to worry about changing or dumping out the resevoir. So far with 95 degree heat and 85% humity that small portable ac keeps my garage at 76 degrees and 35% humity with no problems. The ac costs about 80 cents a day to run 24/7 but I will only run it when me and my wife work in there or if we keep our dogs in there during the day.

1) It was not 95 degrees with 85% humidity outside.
2) It was not 76 degrees and 35% humidity inside your garage.
3) You're wasting a bunch of energy because you've got a single pipe portable. All of that hot vent air that it's blowing out that vent is air FROM the garage. And to make up for it, it's gonna pull air from somewhere, and that typically means through cracks around your garage door... IE, hot moist air.

 

[TangoFoxTrot]

I put 2 split systems, 18K Toshiba Inverter units, in The Shrine. They cool and heat just fine until you open one of the garage doors. It's not the unit's fault....it's the application. I find myself sitting under one of the units as it blows directly on me during hot days. The heater is more reasonable during the winter because the doors stay closed. And, yes, windows = double insulated pane, garage doors = insulated and entire structure is insulated.

Knowing what I know now.....I would have spent my money more wisely/differently.

I find the same thing, to the point I'm not sure I would put a "real" AC unit in my next garage. Instead, some large industrial ceiling fans and maybe an evaporative cooler (but I live in a dry climate).

There's hot days where I don't even bother turning the AC on and instead just position a powerful fan in my work area.

It takes a long time to cool it down with AC, so you have to plan ahead a several hours to really get cool. And as soon as I open the garage door for any reason, I'm basically back to square one. And if you're under a car hood or under the vehicle, the cold air doesn't really reach you.

AC units also really burn up the electric bill, especially cooling down a 100 degree garage and keeping it there.

If you're the type that regularly have all day projects where you will seal the place up and work inside from morning till night, it makes sense. But for someone like me that will maybe be out there 3-4 hours at a time, I find it makes more sense just to get some good airflow on me.

 

[JakeKohl]

My experience is really different. If I'm grinding and cutting, I tend to do that outside if the weather is nice just to avoid having to clean up the mess. I've done this recently in the last couple of weeks - open the door, setup a workmate/drop cord/side-angle grinder, work out there for about 20 minutes. Go back in the garage, close the door, and I'm back in comfortable shape in about 5 minutes. I really love my mini-split and it works very well.