I got a MacGyver idea for a home built AC unit

[V-10 Killer]

First off, the why of it.
*I won't spend a few grand for an AC unit for my garage.
*A wall unit would be an easy entrance point for a burglar.
*Just for the fun of it

So now the idea.
I already have a squirrel cage fan with a discharge aproximately 12"x12" or so. I also have a 3/4" city water line back to my garage. Now all I'd need would be some sort of box or enclosure, a GFCI power supply, a water sprinkler supply valve, and an entact radiator from just about any car in a junkyard.
Same concept as geothermal heating right. And I checked city water prices when I was filling my pool. It's less than $1.50 per 1,000 gallons. And I'd only be running it when I'm in the garage working on something in the middle of summer. I'll have a 12'x13' storage room in the corner I can hide the equipment in.

So from a functionality standpoint, is there any reason why it wouldn't work?

 

[Novadiecast]

That in theory should put out cooler air(Water temp.) but will not remove any humidity at all, humidity is what makes you hot not the temp.

 

[oldgoat]

Actually I knew a guy that the house he owns originally had a big radiator in the atic and had central heat. Well water was pumped through the radiator and it had a fan behind it that blew the air in through the heating ductwork. Said that it worked pretty good and would keep the house in the mid to high 70's when it was high 90's or a 100 degrees. Only problem was it ran the water out onto the ground. Since he had boys he found that water, dirt and boys aren't a good combination. Asked why he didn't just put another well pipe down and route the water back into it and he admitted that he just never thought of it.
True the unit won't take any humidity out of the air, but it won't put any in unlike a swamp cooler. Kind of a middle of the road deal. I would advise against using a used radiator though since it had antifreeze in it I would think that it could contaminate the water system. I would use well water and pull from one and back into another but again with a clean radiator. Maybe have a radiator shop boil the radiator to try get rid of as much as possible. For me I would vote on giving it a try.

 

[malibu101]

Free is always good! There may be a downside or 2 but if no ones going to get hurt-Try it!!

 

[W-Cummins]

That in theory should put out cooler air(Water temp.) but will not remove any humidity at all, humidity is what makes you hot not the temp.

I would be interested in why you think that it wouldn't remove any of the humidity?

William....

 

[Novadiecast]

Just my though as there would be no mechanical means to do it.

Blow a fan on a cold can of pop. The pop cools the air, but nothing to remove humidity.

 

[W-Cummins]

So from a functionality standpoint, is there any reason why it wouldn't work?

Work is a relative term here First you should test the in coming water temp. the lower it is ( the larger the delta T) the better this will work. IF I was going to try some thing like this I would set it up so it would run either like this...

Running as a combination closed and open loop system. I would fill the system up with the cold water ( use solenoid valves) and run a circulating pump to create a loop. The feed and drain water valves would be controlled by a thermostat and would open and close when the temp gets to set points.

OR

You might be able to get close to the above systems performance by just slowly adding and removing the water from the system ( cold in the top and warm out the bottom A thermosyphon ).

In either case I wouldn't waste the water. I would use the discharge water, to water my lawn, trees, garden, etc....

If your feed water is cold enough the system might just work well enough to pay for its operation.


William....

 

[W-Cummins]

Just my though as there would be no mechanical means to do it.

Blow a fan on a cold can of pop. The pop cools the air, but nothing to remove humidity.

It's not a mechanical process. Take your cold can of pop, and put it outside in the shade on a hot humid day and come back in a few min. ... and you will find lots of condensation all over it. Same process at work in an air conditioner or a dehumidifier the warm water vapor condenses on the colder surface (the evaporator in this case) and then drains away.

William...

 

[78fj40]

I'm thinking the idea would work. Really. I would make sure to recycle the water, I like the idea of using the water to feed the grass/flowers/trees. You could even bury a few 55 gallon plastic drums to hold the water and water the grass at night with a secondary pump.

If I didn't already get a great deal on my HVAC system, I would seriously consider this idea for myself.

If you have a well, I also like the idea of back feeding into the ground.

I have a few 55 gallon plastic drums, I am planning on making a sprinkler system that feeds off the downspouts.....I'm already on well water so I can't water the grass all of the time...but the water coming out of the ground sure is cold.....

 

[Steve in Mi]

First, the highest the temp goes in my shop is 72 w/o A/C - it's the insulation that makes it so plus I keep the doors closed unless they are being used to go in or out. Keeping the doors closed not only keeps the heat out but the humidity as well, both of which cost money to get rid of.

I wonder if you might use fin tube to run water thru. Good heat transfer and no contamination to your water.

I'm looking at this fin tube as inner and after cooler pluming for my compressor. Warm air ducted and directed outside in the summer (delta T greater than 70) allow the warm air to stay inside the shop in the winter - save the heat. I'm sure it will cost me more than what I will save but I have the fin tube already and I like a good experiment.

BTW, ground water temperature is 53 degrees plus or minus 1 so it gives only ~ 40 degree delta T with 93 in the shop. The delta T drives the effectiveness of your cooler and it is smaller as you approach a cooler garage. Are you sure you don't want to dig a real deep hole under your slab and bury a cool water storage system for closed loop operation. Probably about the time you want cooling in your garage the pool water is pretty warm already. Out loud thinking. I bid you much success in this venture. As someone already said, go for it!

CORRECTED for ground water temperature. 53 not 63 that I previously typed in error.

 

[VvvJRvvV]

BTW, ground water temperature is 63 degrees plus or minus 1 so it gives only ~ 30 degree delta T with 93 in the shop.

That's odd. Our well water is a flat 50 degrees, year round. I also agree with the fin tube idea. Unless you bought a radiator new, I wouldn't recycle that water.

Now you have me thinking about this. I have 30 trees that require around 1 hour of water per day. This would be a great way to water them and save some money on AC. Hopefully, in the next few weeks I will get to start working on my garage again. I have been pretty much out of commision since February with my back.

* Edited to add this
Now that I am thinking about this, wouldn't this work in the winter too? Isn't this idea similar to a homegrown geo-thermal system? Time to do some research
* End Edit

Keep us updated on your progress, I think it will work.

 

[Steve in Mi]

That's odd. Our well water is a flat 50 degrees, year round.

Thanks for drawing my attention to the error I made. I should have typed 53 not 63. I went back and edited my original post. I take that 53 from published data for North America. I have a spring on my place that runs steady at 52 degrees so I figured the published data to be correct. You measure 50, okay. I did a quick search and see the Geothermal guys are reporting 45 degrees (typical sales pitch I guess), you can see it in the graph at;
http://tristate.apogee.net/geo/gdgwtem.asp

 

[Steve in Mi]

radiator from just about any car

Will a car radiator withstand the operating pressure for your system?

 

[kbs2244]

You can make it a closed loop system by burying a loop of pipe, and routing the water through your radiator, out through the loop to cool off, then back thriugh the radiator. 100 feet of 1.5 inch black poly should do it just fine. In north Mich I would go with a 50/50 mix of antifreez like a car, so you don't have to worry about it in the winter. Put a drain under the radiator. It will act like a dehumidifer and have all kinds of condensation to drain off.

 

[V-10 Killer]

You can make it a closed loop system by burying a loop of pipe, and routing the water through your radiator, out through the loop to cool off, then back thriugh the radiator. 100 feet of 1.5 inch black poly should do it just fine. In north Mich I would go with a 50/50 mix of antifreez like a car, so you don't have to worry about it in the winter. Put a drain under the radiator. It will act like a dehumidifer and have all kinds of condensation to drain off.

You gotta remember, the object of this is to build a system that will lower the temperature directly in front of the workbench from 90-95deg to ~72deg or so, and do it cheaper than installing a pre-build everyday AC system. If I had to trench a 100+ foot trench to bury a closed loop of pipe, pick up a circulation pump and tank, add antifreeze, etc... it just wouldn't be feasible at that point.
I do like the idea of a condensate drain though.

Will a car radiator withstand the operating pressure for your system?

Good question. I'd probaly put a gate valve on the supply, and a drain on the other, so I could use just enough to get the job done. Being open to a drain on the other side, there would be next to no pressure on the radiator.

 

[comp]

window unit with bars

 

[V-10 Killer]

If a thief wants in, they will get in.

Hey, that's my line!

Although that may be true, garage break-ins are very rare around here, and I've never (in this area anyway) heard of someone going thru the wall with a sawzall. Detroit, yes, Chicago, yes, backwoods mid-Michigan in a cul-de-sac subdivision, nope.

I'm merely trying to prevent EASY access points. Hell if they really want in, they can kick through either of the skylights.

But my objective here is not to build a bank vault. I refuse to live in fear of what criminals could do.

 

[cranker]

I have thought about this same idea for a little while now. i was going to run a closed system that has a storage container for the water(large cooler). then have a pump (pond pump) to cycle the water from the container through the rad back to the container. This way i would not be wasting water and i also thought i could fill the container with some ice to help get it a little cooler. That is why i was thinking a large cooler. I have a rad already but that is as far as i got.

Crank

 

[V-10 Killer]

If it works, our systems won't have a very high efficiency, that's for sure.
Most heat transfer from normal refrigeration comes from change of state from high pressure liquid to low pressure gas, which has a much larger delta T (latent heat of evaporation). This system will basically just be a cool breeze for days without, which is all I'm really looking for.

 

[Franz©]

Can it be done, absolutely, and it is done in commercial buildings and schools every day, chilled water flowing thru a coil picks up heat from the air being moved across the coil, and cools the room.

Ain't no big trick to accomplish, unless you want to get into serious efficiency. The amount of thermal transferr that can happen as the air passes the coil becomes the fly in the ointment, and a car radiator ain't gonna cut it. If you gang about 5 radiators behind one another in the air stream you can get efficiency. A second problem in any coil/airstream aplication is how you move the air across the coil. Blowing air across a coil requires equilization difusers, or you get a hot spot in front of the fan, and a lot of unused coil. If you **** the air thru the coil you get more or less equal flow and maximum transferr.

You also need to understand that air passing a coil can only cool so much with each pass. The long and short of this is that you either have a very cold coil to acheive maximum cooling, or you keep running the same air thru the coil acheiving a little temperature loss with each pass.
If you go with the constant air movement plan, you need to control the water flow rate thru the coil so you aren't wasting a lot of water. Fortunately, this isn't too difficult to do with a thermal sensor and a valve, you can even computerize it if you want to really have fun. Ideally, you'd want the exhaust water to be only a few degrees colder than the ambient room temperature, given the propertys of liquid coils and airstreams. This would minimize water consumption as well.

What to do with the spent exhaust water, well, there is always drip irrigation with a spent water tank. That way you don't need to spend a lot of money on pumping water. If you happen to have a flowing creek next to the room you're trying to cool, you are way ahead of the game, presuming you can filter the incoming water so it doesn't plug your coil. Creek water will generally be at a lower temperature than ambient air temperature. Keep your mouth shut about the operation though, or some tree hugger will get DEC on your A$$ about thermally poluting the creek.

Removing humidity from the air, as long as the air side of thecoil is at a few degrees lower temperature than the dew point of the ambient airstream, the coil will condense humidity out of the airstream. Of course you also need to factor in either keeping the air stream speed slow enough to allow the condensation to fall off the coil, or you can't drop a whole lot of humidity out of the air stream. This can be overcome with a trick or two.

As far as ground loops and using black plastic pipe, forget it, standard poly pipe ***** as a thermal conductor.

The best coil units are either the coils used as room boosters in duct systems, or fairly decent sized air conditioner condensers. You need to do a bit of modifing on most AC condensers if you can even get them before the scrap guy does these days.

Just in case you're wondering, I do live next to a flowing creek, and the DEC possum police are real azzholes. Fortunately, I am allowed to pump water for irrigation purposes.

All the above said, you'll keep your workspace a lot cooler by just employing Mother Nature's free air conditioning. Every night after the sun goes down, she lets you pump all the accumulated heat out of the atic space and insulation with a very small fan at minimal cost. Use a clock to control the fan, and you're fairly comfortable for cheap money. Install a louver into the atic space and **** cold air in just above the shop floor, and employ that floor as a thermal battery to keep the room cooler during the next sun cycle.

 

[krooser]

What you're talking about buildiing is just a home made swamp cooler like a port-a-cool unit.

If you want a secure a/c unit put in a split system...one 4 inch hole in the wall.

http://www.port-a-cool.com/