[justgas]

Wow and artistic too. In the words of Franklin, I think that is a rising sun and not a setting sun.

For a similar idea, my mother-in-law told me how her father had rigged a refrigerator by running cold water from an artensian well through coppor tubing inside an insulated box.

I think I remember from Cincinatti that our process water from the city was about 10 C warmer in the summer than in the winter. Water temperature depends on how deep the pipes are buried and I suppose how much sun exposure the pipe route gets.

[Troyboy1208]

I have a 2004 Civic hybrid that provides real time mpg. The difference on a flat stretch of road with low traffic, consistent speed, low winds with the ac on or off is about 1 mpg. Thats at 55 mph. By the way I average around 60 mpg at 55, 55 mpg at 60, 48 mpg at 65, 40 at 70, and 36 mpg at 75. I think its interesting the effect of wind resistance on efficiency. I get better efficiency in the city then on the interstate at 70 mph

[omgwtfbyobbq]

Very nice. Kinda like those fancy passive water cooling systems with water being circulated through pipes in the group to release heat and up to the house to carry more away, except you're just taking the cool water you get from the county and using it to lower temperatures before you use it in a certain area. I wonder how much more this would cool by having the entire house's cold water supply run through it?

[dubled]

Thanks for all of the compliments

I think if I ran all of the water through it I would reduce my water pressure in the house as it would cause a bottleneck at the chiiler coil. It would help cool better that is for sure. Also this being a reused evaporator which at one time had refrigerant flowing through it I would be scared to use the water as potable water.

It is true that If I were in the city I may have a harder time getting rid of the water but Im sure I could think of something maybe a 55 gallon barrel to hold the water until I can use it for the plants or something.

dubled

http://keep-your-cool.blogspot.com/

[TommyJefferson]

There are so many variables it is impossible to say "A/C on is better" or vis versa.

The only sure way to know is to test your car in the conditions you drive in.

[Aimrehtopyh]

Let's be optimistic and say that your inlet temp is 45 degrees farenheit and your discharge temp is 80. This would give you about 291 btus per gallon of water you flow through it. And tecnically your fan is adding 85 watts of heat to your house at the same time. This converts to 290 btus per hour.

Nice, not what I expected.

So my central air unit draws about 2000 watts and runs, let's say, 25% of the time. So over the course of a month it'll consume 360 Kilowatthours while it removes a grand total of about 3million btus of heat from my house. Energy cost: about $25 at todays prices.

So, optimistically you'd have to flow 10,300 gallons of water over the course of a month to remove the same amount of heat from your house. In reality it'd probably have to be double that amount. Plus the 85watts drawn by the fan (lets say it runs continuously) costing you about $4. So your average flow rate would be between .25 and .5 gallons per minute. 10,000 gallons would cost me about thirty bucks.

$64 versus $25 at todays rates sounds pretty sad until you figure in the dozens of trees you could keep very happy by simply moving your discharge hose once or twice a day. Doesn't deep watering encourage deep, healthy root growth?

I was very skeptical at first, now I gotta plant more trees and a garden and do this.

[dubled]

Aimrehtopyh 10,000 gallons a month sounds like a lot to me.

Thats around 13.8 per hour... I think.

I plan on for mine atleast to run maybe 2-3 gallons per hour through it. With a bigger chiller you could probably run more through and thus get more cooling. I guess when you really think about it there is all kinds of things you could do along these lines in a house.

My setup is lilke a vitamin it's a supplement it's not meant take over all of the cooling needs, just help out.

dubled

http://keep-your-cool.blogspot.com/

[Aimrehtopyh]

If someone has an orchard or a large garden it's a no-brainer. The build is super-cheap and plants don't like ice-cold water anyway.

Consider this; 20,000 gallons would cover a quarter-acre garden with one quarter of an inch of water.

Or even better. My total garden space covers about 1/10th of an acre. My town is supposed to average about four inches of rain during the month of July. Say we're in a drought and recieve half this amount. I would have to put two inches of water on my garden to keep it relatively healthy. My meager plot would require 5400 gallons during such a month!

That's a pint a minute for the entire month and would at best remove 1.3million btus. About the same heat removal as running your average window air conditioner 20% of the time.

[dubled]

Yea that would be pretty neat if you could scale this up large enough to really cool a house and then send the water to a large garden or orchard like you said.

If any one out there has a natural spring near their house that would be ideal to tap water out of that, if you could pipe it and use the pressure that it has to send water through therefore not requireing a pump.

I guess the sky's the limit when thinking about adding a chiller to your house.

dubled

http://keep-your-cool.blogspot.com/

[Pops]

Cool idea dubled, I plan on a similar though passive/radiant setup to cool a little storeroom that I’ve insulated really well. Actually the idea came to me from the springhouses that used to be common.

Just going to run water from the well (425ft deep) through 5 or six copper pipes mounted to the ceiling of the 5x10 room. We have quite a few animals and water troughs running off the well so in the heat of the day the pump probably runs fairly often, I’ll oversize the whole thing by 2x so as not to add additional restriction.

Congrats and thanks to Aimr for the review - sometimes I’m sure my rigged jobs cost more than they save!

[Etalon]

Why would you have the windows down anyway if the AC is off? Just use the fan without the AC on.

According to a topgear episode, where they tried to drive as efficiency as possible (no idea which episode) it did make a coupla mpgs difference.

-edited to correct one of the more glaring spelling mistakes-

[dubled]

I've heard that water on roofs also really helps cool a building down. My old boss had a system like that where he would sprinkle the roof in the summer, neighbors thought he was nuts but it stayed pretty cool in the building for us.

I could send my dishcharge water onto the roof and then down the gutters and catch it for the flower garden. Basically the water would wick away heat from the roof in turn keeping it cooler inside.

I am not sure this is that great of an idea for asphalt roofs but for a steel roof or galvinized it would be great.

dubled

http://keep-your-cool.blogspot.com/

[gw]

Those mythbuster guys ran a test of ac vs windows down, and found that it is more efficient to have the windows down:

Jamie's A/C car ran out of gas first -- Adam's windows down SUV ran for another 30 laps -- completely contradicting the computer mpg estimate. Computer estimate based on air flow into the engine, so it would appear that it is unable to properly model the difference between A/C and windows down.

Mythbusted

Unofficial Mythbusters: Episode 22

In addition drivers of the Honda Insight find that driving with windows down is more efficient than ac:

"Switch the AC on, and there's a 5-10 mph drop."

InsightCentral: AC vs. Open windows Gas milage thread

There are many factors involved, such as driving style, aerodynamics, efficiency of ac system, etc, so it is difficult to conclusively prove which is more efficient. Highly efficient vehicles like the Honda Insight might have a completely different result compared to a SUV.

[Rabbit]

I have done quite a bit of milage testing on my motorcycle and I have found my best milage is at 45 mph. This is the slowest speed that I can maintain in 5th gear without lugging. My milage goes from 40 mpg at 65 to to 58 MPG when driving at 45 mph.

[smallpoxgirl]

Why would you have the windows down anyway if the AC is off? Just use the fan without the AC on.

Because a car with closed windows is fundamentally the same design as a solar oven and I don't like being well done. Besides my dog would have heat stroke if I closed the windows. Little heater fan doesn't push nearly enough air.

[frankthetank]

A buddy i went to school with had a home made jobbie in his house. NOt sure the specifics of it, but it worked. It also helped that his dad was some sort of engineer for Trane company (American Standard) which is based here in LaCrosse.

GOod job though, my bro just got an estimate for a rental of his and it came back $2000...

[Texas_T]

I have never studied any actual numbers for car AC, but in general:

One Ton of Refrigeration (12,000 Btu/Hr) requires about 1 Horsepower, this is a rule of thumb for an older system that is not very efficient. So modern systems can do betther than that, and one ton is about enough for 400 square feet of office space (high internal loads) or maybe 800 square feet of typical residential space. How many tons refrigeration for a car AC? I have no idea, but 1/2 ton would seem generous for a typical car.

So 1/2 Ton x (max) 1 HP per ton = maybe 1/2 HP and that is at "peak" load or the hottest worst condition.

Compare that to a car engine - maybe 105 HP for a small car engine - and you can see that its a small percentage.

[JustinFrankl]

In nearly every car I've personally driven, I can feel the drawdown on the engine when the A/C is engaged vs. not engaged. From crappy little foreign cars, to big American cars, to sports cars.

In addition ... A/C vs. windows down? Where was the "control" group, meaning no A/C and windows up? The proper test would have also involved variations in outside temperature, and variations in the models of cars.

All these tests show is that for the model tested, energy "lost" to A/C is equivalent to efficiency lost in increased aerodynamic drag.

This is nowhere near a scientific test. It's pablum designed to soothe the masses, encouraging driving when it's really hot outside.

[Doly]

All these tests show is that for the model tested, energy "lost" to A/C is equivalent to efficiency lost in increased aerodynamic drag.

But that's the point, isn't it? When it's hot, you're either going to use A/C or pull the windows down. Nobody is going to voluntarily bake in the car.

[Roy]

A conventional auto air conditioner draws about 6 horsepower from the engine to run the compressor and fans at maximum cooling

from here

at the Rocky Mountain Institute.

I always thought it was around 10-15hp, but I learned that way back when, when automotive a/c compressors were large and inefficient (compared to today's), like the cars and engines of that time.

6hp sounds about right to me, if not a little on the low side.

On the highway, my car shows a roughly 2 mpg decrease on the Inst MPG with a/c on vs. off.

Around town that decrease becomes much more pronounced (~5 mpg). And I can feel the power loss when I turn on the a/c. This is with a 260hp engine/manual transmission in a 3100 lb car.

A 1hp difference is not noticeable to a driver in "seat of the pants" terms. I say this from years of experience in drag racing, and analyzing elapsed times and trap speeds. My personal threshold is about 8-10 hp, as far as being able to "feel" it while driving a car, based on experience. I can go into more detail about how I determined that number if desired.

I can definitely "feel" my a/c slowing the car down, except at full throttle where the computer disengages the compressor for maximum acceleration.

My car always gets better mileage with the a/c turned off. That has been true with every car I've owned that had a/c. More powerful engines seemed to show less effect on mpg than less powerful engines (ie V8 vs I4).

YMMV