Cooling the garage.....

[jtbinvalrico]

I live in FL.......and it's blazing hot in the garage. I usually use my big air mover to break the heat, but it's still stifling. I may have an idea:

I've looked into what are called Swamp Coolers and the Port A Cool units. The main problem here, if I understand them correctly, is that you are going to have a significant humidity increase in the garage due to the misting of water.....if I'm wrong on that, please correct me.

Some time ago, I built a unit designed to heat my pool using hot attic air. (A company called Solar Attic makes this product commercially). What you are basically doing is piping water from your cool pool into the attic and through a radiator while using a fan to blow the hot air through it. The moving air pulls the "cool" off the water, resulting in warmer water being returned to the pool. What I immediately noticed about my unit in operation was the tremendous amount of cool air blowing into the attic as a result of this liquid-air heat exchange.....I tripped into a HeatPro heat pump for my pool. The heat pump was so efficient that it caused me to abandon my project....By efficient I mean 89 degrees in the pool for 9 months of the year at about $40 a month to run it.

So, what did I learn from all that? I had considered revisiting the idea in smaller form to cool my shop. The idea calls for a fan, radiator, and water. The question was in the water....I would need a source of circulating water to allow this "heat exchange." I could simply use a reservoir of water in a tank.....but that water would heat up and lose it's effectiveness while in use. I could source water from the pool, pump it toward the shop and back to the pool to get the effect, but that water is already hot enough.

My idea: Bury a loop of pipe in the ground alongside the house to act as a heat sink. Build a box for the fan. On the back side of the box situate a radiator(s) through which the water will be circulated with a simple pump.

So I submit this idea to the forum. I've learned a little about Delta T and such from an engineer buddy.....but I'm a tinkerer, no expert. My first step is to take some temperature measurements to help determine how deep the pipe should be buried.

My original project had four Honda Accord radiators situated in a cube, with the top sealed and the fan exhausting on the bottom. The system was pumped off of my 1hp pool pump and added maybe 4lbs of pressure to my filter gauge. I used about 80' of 2" flex piping. The fan moved about 6000cfm. The amount of cold air this thing made was crazy.

Questions/opinions sought:
1) How long should this pipe be?
2) What material for the pipe, to best facilitate the heat exchange in the ground?
3) What size pipe?
4) What flow rate should be sought?
5) How deep should this pipe be buried?
6) My garage is standard two-car.....how many cfms on the fan?
7) I had about 1500 sq inches of radiator....How many to cool the garage?

Lots and lots of variables here.

 

[Graymills - Craig]

Hey there.

You are right about swamp coolers. They work well in dry environments but aren't too effective in damp places.

As to other options, I'll throw out a random one: http://www.vortexair.biz/Cooling/ColdAirGun/coldairgun.html. You'd have to pipe the hot exhaust outside, but if you're already running a compressor, it's not a bad little unit.

 

[Torque1st]

As to other options, I'll throw out a random one: http://www.vortexair.biz/Cooling/ColdAirGun/coldairgun.html. You'd have to pipe the hot exhaust outside, but if you're already running a compressor, it's not a bad little unit.

The cooling gained will be far less than the heat dissipated from the compressor.

How far down is the water table?

 

[Graymills - Craig]

The cooling gained will be far less than the heat dissipated from the compressor.

How far down is the water table?

Oh fine, throw the laws of physics at me.

I should have clarified that where I've done this, the compressor is on the other side of the room, but the gun blows over my work area. We couldn't run regular HVAC in the area because of hazardous atmosphere concerns.

 

[Falcon67]

I've looked into what are called Swamp Coolers and the Port A Cool units. The main problem here, if I understand them correctly, is that you are going to have a significant humidity increase in the garage due to the misting of water.....if I'm wrong on that, please correct me.

Swamp coolers work by evaporation cooling with the squirrel cage fan (or other) pulling air across the pads. Works like gangbusters in dry climates like NM, AZ, etc. In places like south Texas, FL, the gulf coast - they just add to your misery. A plain fan works better.

What the heck kind of 6000 CFM fan did you use? My wife wants an above ground pool and my main complaint is that those cool rather quickly in the late summer and fall. Plus our only decent location is shaded in the afternoon. But it's right next to the shop, so an attic heat exchanger for a pool has my tinker bell ringing like crazy. We have a 1 HP sand filter that I kept from an older installation that works 100x better than the **** they pack in the typical pool package at Sams. Plenty of volume.

 

[jtbinvalrico]

I used a fan like this: http://www.globalindustrial.com/p/hvac/fans/wall/oscillating-wall-mount-fan-24-diameter-2

Here are some photos of the unit I made:












Some points....The fan noise may or may not be an issue in your attic.....depends on where you place it. Use only new radiators. You are going to have to closely monitor your pool water to make sure you rein in corrosion issues. The commercially available versions of these go for about $4000 to $5000.

The unit has since been taken apart to be used on this project.

 

[Socophreak]

There are residential systems like this around.

The hot water comes out of your house, goes through the much cooler ground (cooling off) then comes back into your house to be heated up again, thus removing more heat from your house.

From what I've resarched, You wouldn't need more than a 50FT loop of polyethylene. sunk below the frost line (don't want pipes to freeze). Doubt you'd need more than 1'' pipe.

Thats about as much as I can provide. The best bet would be to fool around with the rest of the variables.

 

[jtbinvalrico]

Awesome. Thanks.

 

[chopperman1]

This is cool stuff. Anyone have more info on this? Links website? I plan on moving to AZ in the next year and they have a good climate for a system like this.

 

[Woodlands1]

Hi - My Father In Laws garage is heated by a Cozy wall gas heater(all in one with blower)and is cooled by a duct-less ac unit.The building is cinder-block and has no insulation - yet it stays warm in winter/cool in summer.

 

[Car54]

Have you guys looked at split ductless air conditioning systems? I'm planning to put a 12k BTU unit with heat pump in my shop and a 9k in the office next to the shop.

Jtbin, I'm in Lutz.

 

[darkbuddha]

Seems all us Florida folks are suffering the same thing... heat + humidity = miserable garage. I did some research and apparently most of the heat transfer into the garage comes from the garage door(s). Supposedly, insulating the garage door can reduce garage temps 15-20 degrees in hot climates like ours. It's on my list for sure.

I figure a well insulated door with some good weatherstripping to seal up the door edges and seams, add a small window or split a/c unit, and the garage should be a dream to work in.

 

[Falcon67]

Nice detail and engineering on that. Fan noise wouldn't be a problem using the shop attic. I might simplify that by using two 31 x 19 dual 1" core aluminum radiators from Summit. Under $400 for the pair. You can pass a lot of air through a couple of those.

http://www.summitracing.com/parts/SUM-380331/

Kick *** fan CFM.

 

[Gary S]

First make sure your garage is properly insulated. Then forget all the expensive and high tech ideas. Just go out and buy a cheap $200 window air conditioner that puts out about 10k btu. Also pick up a $40 ceiling fan at the same time. A 2 car garage that is well insulated will cool nicely with that kind of hardware and depending on the price you pay for electricity, it will run for 7-10 cents an hour.

 

[jtbinvalrico]

...just for info....I picked those radiators up off ebay for $40 each, shipped.

I really, really wish I had some land around me. I'm in suburbia with neighbors crowding both sides. I've been looking into how I could get that hot water far enough into the ground and then back out. With neighbors all around, the only route seems to be down. I've contemplated using a water drill (PVC with a hose on one end, works very well), but I would have to use a bunch of these....furthermore, I was dismayed by the cost of copper tubing to make coils to drop into said holes.

Anybody who has some land could do this: dig a pit, put maybe ten barrels into said pit, cover with dirt.....you will have created your own underground heat sink for a project like this.

I'm left with the pool as a heat sink. Unfortunately, the water is already at 89*, limiting it's efficiency as a heat sink......and I don't want that water any warmer.

I may have to reconsider the AC route. Any opinions on which is better.....a dedicated window unit or branching a vent off the main house AC system?

 

[darkbuddha]

I may have to reconsider the AC route. Any opinions on which is better.....a dedicated window unit or branching a vent off the main house AC system?

I thought about this for a while... the problem with running a vent off the main house a/c is that the thermostat is inside, and once the temp inside gets comfy, the a/c just shuts off, thus leaving you in a hot garage. And it would be trying to cool the garage even when you're not there... even if you close the vent to the garage it'll still leak some. Not very efficient generally.

A window unit on the other hand works on demand as needed and has its own control/thermostat. I've even thought about setting up a small solar array to provide electricity for the a/c unit, which would make it pretty cheap to run. That said, I have no idea how much power a solar array would need to produce to power a window unit, so it's strictly theoretical as to how cost effective doing so would be.

Just my $.02.

 

[Gary S]

I don't think solar power is even close to ready to power an air conditioner. For a small garage, expect to use at least a 10,000 btu to make any difference. The new 10,000 btu units eat about 1kw of AC power per hour. Solar is probably rated in milliwatts or watts, not kilowatts unless you spend a King's Ransom to build it.
At 7-10 cents an hour for electricity from the power company, you can't ever pay for solar panels unless you live 1000 years and run your air conditioners 1000 days a year.

 

[jtbinvalrico]

Good point on the thermostat......A window AC it is.

I have no windows, and would be punching a hole through cinderblock. Should I mount it high or low?

Also, from what I've read here, I need to add insulation to the garage door and additional insulation to the ceiling above the garage.......anything else to aid efficiency?

 

[darkbuddha]

I don't think solar power is even close to ready to power an air conditioner. For a small garage, expect to use at least a 10,000 btu to make any difference. The new 10,000 btu units eat about 1kw of AC power per hour. Solar is probably rated in milliwatts or watts, not kilowatts unless you spend a King's Ransom to build it.
At 7-10 cents an hour for electricity from the power company, you can't ever pay for solar panels unless you live 1000 years and run your air conditioners 1000 days a year.

You'd be surprised I think... depending on location, home design, solar array efficiency, etc., some solar arrays have been shown to provide enough power to get homes 100% off the grid, and even give back to the grid for a rebate from the power company. I think it's something like 45 states in the union that actually offer such rebates when you can add power to the grid.

That said, such solar arrays are still very very pricey... give it 10-15 years though, and I'm hoping we can all start to afford such things... especially in sunny and hot climates like Florida, Texas, and the southwest.

 

[John Timmins]

Keep in mind always, that the money you'll save with solar will happen only if you NEVER have to have a service call with 1 or 2 men plus parts in your lifetime.

 

[NUTTSGT]

Good point on the thermostat......A window AC it is.

I have no windows, and would be punching a hole through cinderblock. Should I mount it high or low?

Also, from what I've read here, I need to add insulation to the garage door and additional insulation to the ceiling above the garage.......anything else to aid efficiency?

I'd mount it higher rather than lower since cold air sinks. The other factor of mounting high is it would be harder for somebody to push it in to gain access to your garage.


Insulate your garage the best that you can, insulation pays for itself over time. If your ceiling is open to the roof, definately get that thing closed in. Do you have any gable vents or any other vents to vent out the hot air out of the attic ?

 

[hobie1dog]

Have you guys looked at split ductless air conditioning systems? I'm planning to put a 12k BTU unit with heat pump in my shop and a 9k in the office next to the shop.

Jtbin, I'm in Lutz.

I put in a Mitsubishi split system in my garage 2 years ago...works fantastic and very little fan noise....being a heat pump, it throws out the heat in the winter too.

 

[luvair]

I put in a Mitsubishi split system in my garage 2 years ago...works fantastic and very little fan noise....being a heat pump, it throws out the heat in the winter too.

What sq ft is your garage and what BTU / ton unit did you buy?

Agree it is smart way to go. TIA.

 

[Car54]

Mine's going in this week. I went with LG 9k + 12k. Cost on the unit is $2.4k but you get 30% back as a tax credit. Much more than a window shaker, but the power consumption should be much less.

JTB, want to buy my shaker? It's a Frigidaire with thermostat, it's rather large...maybe 10k BTU with no heat. Don't even know a price yet.

 

[CUSTOMMANCAVES.COM]

I may have to reconsider the AC route. Any opinions on which is better.....a dedicated window unit or branching a vent off the main house AC system?

As mentioned in a previous post, NEVER branch off from the main house into your garage. First off, this is not to code and secondly, this is very dangerous...will allow fumes (including carbon monoxide) from your garage to enter your home.

In lieu of cutting a hole in your block wall for a window-unit, a mini-split unit will only require a small hole in the wall to allow for the plumbing/electrical to penetrate.

 

[sstruckguy]

Good point on the thermostat......A window AC it is.

I have no windows, and would be punching a hole through cinderblock. Should I mount it high or low?

Also, from what I've read here, I need to add insulation to the garage door and additional insulation to the ceiling above the garage.......anything else to aid efficiency?

I live in the midwest/midsouth, and we suffer from the same high temps and higher humidity. The thing we don't have, is an ocean breese.

My 28 x 40,(1148 sq ft) had a similar sweatbox enviroment in the summer months. As of 2 days ago, I installed "2" 8000 btu, window a.c units. (110 volt)

Findings after 48 hours:

1) Power usage- who cares? Its cool(er) inside!
2) Temp difference- 10-15 degrees cooler than outside
3) Humidity difference- at LEAST 25% less (85-90% compared to current of percent)

List of pluses:

1) Sweat isn't dripping on your latest wood working project
2) Sweat isn't dripping on/in your latest computer build
3 You actually can enjoy your shop/garage with out sweat running down the crack of your...personality

I originally planned to have a central heat/a.c unit during the original build. My hvac contractor puked on my plans and therefore my unit. I have been limping along for over 4 years.(and many more in past years)

Long and short:

Costs a little more? so focking what!!

Comfort and productive time spent? A ++!!(plus wifey **** points)

Anything else matter? nope

p.s I just turned 51. I am FAR more productive, when I'm in my comfort zone

 

[jdub63]

Given the heat in north Texas, I've been looking at used central air units for my shop. I originally looked at the mini-splits but was advised that the mini-split didn't provide enough "throw" to cool the 30x30 part of the shop.
Does anyone have experience with the mini-split or even a window unit that could support a 30x30 room with 11 foot walls and a peak of 17 ft? (it is a insulated metal building with an open attic)
I like the idea of the heat exchanger, but I'm not sure it's worth the digging/trenching required.

 

[Falcon67]

30x30x11 with a 17' peak is going to require a LOT of AC. Sounds like 18K to 24K for that space.

I'm in west Tx and it do get a little warm out here. We've had so much rain this year that when we get over 90 it feels more like Houston than it should.

I have a 20x24, walls full of batt insulation and the same R-13 3 1/2" bats on the ceiling (8'). The 8x7 overhead door is layered with pieces of 1" pink foam board. I have a 12K window unit high on the wall opposite the big door. It's rated at 12K but it's a weak one IMHO. I can keep the temp in the 70s even on the hottest days. Most of the time, I have the unit set on 3 and reserve 5 for the really hot stuff.

Calculator:
http://www.consumerreports.org/cro/...r/air-conditioners/sizing-worksheet/index.htm