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THE AC/Heat Exchanger Thread (merged)

How to save energy through both societal and individual actions.

Re: low-tech cooling

Unread postby Bas » Thu 27 Dec 2007, 01:13:31

Image


....also, I read in ancient manuscripts that people used to exploit the shade from trees or other things in order to keep cool. Pretty clever when you think about it actually.
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Re: low-tech cooling

Unread postby steam_cannon » Thu 27 Dec 2007, 01:41:05

gg3 wrote:Re. radiators in your incoming water line:

DANGER there is LEAD in the solder joints in those things and there may be a risk of it leaching into your drinking water.

Automobile radiators were used as components in illegal distillation systems during prohibition and there was a serious problem with lead contamination of the resulting alcohol beverages.
All the pipes in the 100+ year old building I'm living in use good old lead, it hasn't seemed to affected OMG monkey's everywhere!!! 8O

Hahaha, a little joke. But you're right. I should make a point in saying that lead free is the way to go!

Going lead free wouldn't cost that much.
* It would cost around $350 to get a nice new lead free radiator.
* It would cost about $150 to make a nice lead free one out of coiled copper piping.
* I'm guessing about $100 to make one using using Aluminum ridged tubing.
* About $50 to make it using coiled polyvinyl tubing.
* And about $25 to use coiled garden hose... :lol:

gg3 wrote:If you use a radiator hooked up to a nearby stream, you could also be discharging lead into the stream.

This is an item that absolutely requires a) lab testing of the water output, b) development of sources for safe radiators that can be standardized: a specific manufacturer and part number.
Regarding lead in a pond, a couple lead sinkers in a pond would probably contaminate it more then an old radiator. But I do agree, that lead free is the way to go.

gg3 wrote:Note also, the power consumption to circulate the water between a radiator and a storage tank, needs to be factored in.
It's going to be factors of ten lower then a radiator compressor pump. A solar powered pump, dam pressure or regular water pressure should all use much less energy then a standard air conditioner compressor system. :-D

gg3 wrote:Last but not least, lukewarm water is a notorious breeding ground for bacteria and biofilms (slime) inside water pipes. You do not want to be drinking untreated lukewarm water.
Yeah and don't eat the yellow snow, thank you gg3. Anyway rapidly used chlorinated warm water doesn't cause a problem in the water pipes in my building. But ideally this set up would use a pond and if it's water from a pond back into a pond, I think it's pretty worry free. Worst case, the system would require lots of cleaning filters and have to be reamed out once a year. But anyway, wouldn't it be cool to have fountains in a pond that also keeps your house cool!
Last edited by steam_cannon on Thu 27 Dec 2007, 05:34:21, edited 2 times in total.
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Re: low-tech cooling

Unread postby steam_cannon » Thu 27 Dec 2007, 01:46:43

Bas wrote:Image


....also, I read in ancient manuscripts that people used to exploit the shade from trees or other things in order to keep cool. Pretty clever when you think about it actually.
Darn you Bas! If my wife reads this I'm going to be stuck using that fan Cleopatra style all day when it's TEOTWAWKI! :lol:
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Re: low-tech cooling

Unread postby gg3 » Mon 31 Dec 2007, 10:30:53

Hand-powered fans are nice but the problem is that there is a slight net heat gain by the body due to the energy expenditure (even though it seems slight) of using them. Their effectiveness depends entirely on the ambient temperature being far enough below body temperature, and ambient humidity being low enough to allow evaporation of sweat.

Strategic use of small electric fans is also a viable strategy, also dependent on ambient temp being below body temp and ambient humidity low enough to absorb evaporated moisture, but with wider range of effectiveness since there is no heat gain from activity (e.g. fanning oneself with a manual fan).

What I normally use is a fan that pulls about 6 watts, directed to my head (your head is the largest source of heat in your body).

The micro air conditioner design is intended for future use in an area where higher summer temps are likely.
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Re: low-tech cooling

Unread postby patience » Wed 06 Feb 2008, 19:10:08

Does anyone have energy data on the old evaporative cooling towers used on factories and large buildings? Seems like it might apply to home cooling, if it is more efficient than refrigeration. It wouldn't be hard to build, very low-tech, and recycles the water. I have heard that the water needs periodic treatment to combat slime.
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Re: low-tech cooling

Unread postby davep » Wed 06 Feb 2008, 19:25:33

gg3 wrote:Hand-powered fans are nice but the problem is that there is a slight net heat gain by the body due to the energy expenditure (even though it seems slight) of using them. Their effectiveness depends entirely on the ambient temperature being far enough below body temperature, and ambient humidity being low enough to allow evaporation of sweat.


The ambient temperature isn't really an issue, it's more the sweat that helps (and humidity that hinders). Obviously, due to the latent heat of evaporation, the face or body is cooled (probably above the energy expenditure in wafting the fan). A worthwhile addition to this is to re-use an old window cleaner bottle (that sprays a mist) and periodically spray yourself with a mist of water. It does the job for me.

Responding to the original post, I heard that the "clay eggs" are used to cool water, as a small amount can seep through and evaporate, keeping the clay egg cooler.
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Re: low-tech cooling

Unread postby vision-master » Wed 06 Feb 2008, 19:29:41

You need a minium of 47 degree "coil" to pull out the humuggity.
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Reducing energy consumption (AC's) in hot climates

Unread postby mekrob » Mon 25 Feb 2008, 21:20:14

So I was thinking about living in hot climates and what that does to your energy bill. I was wondering and thinking about ways to reduce energy consumption if you were to build a house from scratch. One of the ways I was thinking about that I'd like some input on goes something like this.

We all know that hot air travels up, cold air down. So say you're in a hot climate but energy is not that cheap nor available at demand (hey, aren't we heading to this place?) What I was thinking was if you were to have the ceiling of each room tilted just slightly (or more if possible). You'd have to imagine a house or building with at least two rooms per side.

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Like so.

This way you're able to turn the ceilings into little V's, except with angle very high (175 degrees, at least). This way, you have a support beam in the middle to help prevent a collapse. Now the hot air will rise up to the ceiling as usual. But currently, the air at any point at the ceiling is about the same as any other. But with the tilt being directed towards the outside of the house, the hot air will rise again towards that direction. Here, you could have a little ventilation shaft that allows the air to go out, but a screen would prevent bugs from coming in, and of course this can be closed during rain, etc.

I'm thinking that the climate would have to be very hot, at least 100 F for this to be possible. Of course, this wouldn't make it 70 degrees, or even below 90. But it would prevent the hot air from being kept inside the home and thus regulate temperatures better.

So would having a ceiling that is not level cause a major problem with the stability of the above floors/roof (it wouldn't bend in the middle of the room, but at the wall between two rooms in a house)? Or would this possibly work to some degree?
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby timmac » Mon 31 Mar 2008, 00:17:05

What climate are you talking about, dry or humid, here in the southwest like Vegas, you can use a swamp cooler verses a a/c unit, its a low electric usage and could use a solar panel for this type of unit, building the walls the way you have mention dont work here because its hot every where, 110 degrees in the shade, shade trees are the best bet to help keep house cooler and no windows facing south, if you are not living in a hot climate now, moving to a hot climate can be hard, I have been here for 21 years and still can not stand the heat.. Under ground house's are great in the desert, they stay cool all summer long, no a/c or swamp cooler,, check Vegas out in Augest and see if you can stand the heat before you make the move...
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby kpeavey » Mon 31 Mar 2008, 06:52:32

Here, you could have a little ventilation shaft that allows the air to go out, but a screen would prevent bugs from coming in, and of course this can be closed during rain, etc.

This device is commonly referred to as a "window"

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Re: Reducing energy consumption (AC's) in hot climates

Unread postby GeoJAP » Mon 31 Mar 2008, 08:38:41

I live in Central Texas, where it can get up to 100-105 for 30-40 days straight sometimes in the summer. I have two experiences I can share with you.

One person I used to know built a house out in the country, about 30 miles east of Austin. It is a wooden, three and a half story house, that is open all the way through the middle of it. There are stairs and balconies in the house, that lead to rooms off to the side of the central open area. It is not very wide, but very tall. It has no air conditioning and uses solar panels. It is completely off the grid. It is designed to carry the hot air up and through the house in the summer. Does it work? Yes, as well as it can, but it's no ice box.

Another was a house that I built out in the country and no longer live in. It was a conventional 2400 square foot home, which had bare concrete floors, 9-10 foot ceilings, ceiling fans and an extremely tall roof and roof peak. This house would stay amazingly cool in the summer without AC. I think it was because the roof angle was so high, and the attic had so much volume, that it did a great job of buffering the inside of the house from the sun's energy. We had no shade trees in this location either. The cool concrete floors, lots of windows and 9-10 foot ceilings also really helped to keep air moving through the house. It was a very breezy, cool house. It was a little big for my tastes now, but I miss it as it was a very well designed house.
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby TreeFarmer » Mon 31 Mar 2008, 09:43:41

Just a general observation here. A well insulated house takes quite some time to warm up on a hot day. If you have a location with cool nights and hot days such a house can be opened up at night to take advantage of the cooling and then kept closed up during the day.

While this is no panacea it will often keep a house very comfortable until say 2 or 3pm. After that it may start to get warm insiade the house but being able to go over half the day with no AC is not bad.

Personally, when it comes to lowering AC costs, or even not needing one nothing beats a good design for your location.

Most likely, if I ever build another house, it will be out of the styrofoam blocks that you fill with concrete and if is in a hot location, it will have wide eaves so that the summer sun never hits the walls of the house except in very early morning and late afternoon.

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Re: Reducing energy consumption (AC's) in hot climates

Unread postby Ludi » Mon 31 Mar 2008, 10:46:14

I live in Central Texas and we don't use AC in the house. On the very hottest days we close the windows in the morning, to trap the cool air, as TreeFarmer mentioned. The house stays a few degrees cooler than the outside, though still rather hot. Our house is poorly insulated, with cheap windows.

Here's some links:

http://www.builditsolar.com/Projects/Co ... ooling.htm

http://www.azsolarcenter.com/technology/pas-3.html
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby Roy » Mon 31 Mar 2008, 12:42:44

When our A/C unit failed last June, we decided to forgo the repair and do without,.

Last summer was one of the hottest on record here, with a stretch of what seemed like weeks of temps near 100.

We do have an attic fan. What we would do is similar to what Ludi described. Keep the house closed during the day, and as soon as the sun went down, open up the house, and crank up the attic fan.

That would draw cooler air into the house and usually get the temp down to the low 70's inside by about 10 pm.

In the morning, shut the windows, lower the blinds, and wait.

By about 4 pm, the inside temp of the house would creep from 73ish to about 84ish.

Not too bad if you're dressed properly and acclimated. Then the sun goes down, and do it all over again.

My electric bill last summer was approximately half what it was the summer before when I was still using the a/c.

Most guests complain and guffaw when we tell them we don't have a/c.

The way I see it is that eventually, electricity will become very expensive, and air conditioning will be seen as a luxury rather than a necessity, as it once was.

You're on the right track in looking at ways to get along without it.

Of course, large shade trees, awnings, and house orientation can also make a difference.
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby skyemoor » Mon 31 Mar 2008, 12:57:49

What you are referring to is a solar chimney. This has long been a practice, though relatively recently abandoned with the advent of A/C. George Washington used one in his Mount Vernon home in the form of a vented cupola to draw out hot air at the top of the house. Indeed, that is the primary purpose of the cupolas you see on the ridgelines of older buildings.

There are many variations in design.

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Re: Reducing energy consumption (AC's) in hot climates

Unread postby 3aidlillahi » Mon 31 Mar 2008, 13:22:52

Hey, Mekrob's new name here.

Thanks. I'm looking into ways for sustainable "urban" living (more like condensed rural) so that second design from the above post is just what I was looking for. But time constraints due to the failing US economy could mean I have to build only a home for myself, so either way, this was a lot of help with plenty of details and advice.
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby TreeFarmer » Mon 31 Mar 2008, 20:44:47

Does anyone know how much energy a small window unit AC uses? If solar keeps getting cheaper the day may soon come where you can run a small window unit with a few solar panels and keep a well insulated house very comfortable throughout the day.

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Re: Reducing energy consumption (AC's) in hot climates

Unread postby Tyler_JC » Mon 31 Mar 2008, 21:17:14

http://www.walmart.com/catalog/product.do?product_id=4456965

This particular unit produces 10,000 BTU (or 2.93kWh) worth of cooling.

Divide that by three to find the electricity use.

So if you keep the thing running for 10 hours a day for 100 days in the summer time...that's 1 megawatt hour of electricity just for that one unit, which can only cool is mid-sized room.

That can cost you anywhere between $100 to $200 depending on your location.

Add in a few more rooms and it starts to become a serious drag on the budget.
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Re: Reducing energy consumption (AC's) in hot climates

Unread postby TreeFarmer » Mon 31 Mar 2008, 21:52:01

In a well insulated and well designed house I bet that would keep 1000+ sq ft cool.

That is the point I was getting at, with a well designed house your AC bill does not have to be onerous.

Four years ago we built a new house here in PA that is 2350 sq ft (single story) with a full basement that we also heat. We moved into this house from a 1500 sq ft house built in 1967 with a 1000 sq ft basement that we only partially heated. The 1967 house had decent insulation and newer double-pane windows so it was not a total energy hog.

The heating bill in the new house was 20% less than in the old house. Of course that is the result of better insulation and a more efficient furnace. I'm betting the majority of it is due to the insulation, we have 6" walls with blown in cellulose.

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Re: Reducing energy consumption (AC's) in hot climates

Unread postby skyemoor » Tue 01 Apr 2008, 16:18:17

TreeFarmer wrote:In a well insulated and well designed house I bet that would keep 1000+ sq ft cool.


That depends on a lot of factors, from humidity, temperature profile, temperature settings, window shades, interior activity and energy uses, etc. A 'super-insulated' house will drastically reduce one's HVAC energy requirements, though careful shading of windows from the sun is required. Some strawbale home walls achieve R-50, though windows tend to be the Achilles Heel of low-energy design.

Most window units are also of low to middling efficiency, so smallness does not imply the best choice.
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