# cooling the house with creek water ??



## copperhead46

We have a year round creed about 100 feet from the house and are wondering about using some kind of re-circulating system to cool with, have any of you done something like this ? If so, can you steer me to some sources for info, or please share your experience, thanks


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## rockhound

Sounds like a good way to get some cooler air in the house. Condensation around whatever coils you use might be a problem. How much higher up is the house from the water level? Bigger pipes carry more water, thus more "cold" but also take a bigger pump, so you've got some math ahead of you. Good luck, I think it can be made to work!


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## copperhead46

we're probably 60 feet up from the creek, hopefully someone will know where I can find all the info I need


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## TnAndy

You could probably rig up something, but it's gonna take a LOT of cooling surface compared to a freon based AC. Freon "boils" at about 30 below zero......that is, it changes from a compressed liquid to a gas, and in the process, has to absorb a lot of heat from the air passed across the coil to do so....."making" cool air. The Delta T ( temp difference ) is something like 100 degrees between the boiling point, and your room temp. (say 80)

In comparison, the creek water might be around 50-60 degrees (maybe higher), so the Delta T would only be about 20-30 degrees with an 80 degree room. So you can see it will only be about 1/5 as efficient, meaning LOTS more coil surface, (HUGE most likely) and more flow.

The upside is the equipment is cheaper, for example, you wouldn't need a compressor or condenser coil ( the outdoor unit on an AC ).....just dump the slightly warmer water back in the creek.


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## Harry Chickpea

TnAndy is on the right track.

Cooling is a science. It is possible to cool with water, but tricky. The key issue is that creek water will not generally be below the dew point of the air, so even if the air is cooled, the relative humidity will go up and it will feel damp and clammy. A standard AC is designed to remove the moisture from the air (which takes a huge portion of the energy cost).

If your air is desertlike, then you can use a swamp cooler (Google is your friend).

The other ways around the beast are trompes and eductors. A trompe is fascinating, but takes a considerable fall to work properly. They are used in mines, and there used to be a restaurant in Vermont that was cooled by a trompe. How to describe...

Imagine a 32 ft waterfall. Now imagine that waterfall going into a pipe, with a grate or other mechanism to fill the waterfall full of air bubbles that get pulled down with the water into the pipe. The water and bubbles of air go into a chamber at the bottom and the air gets piped off. The trick is that the air has been in contact with cool water while being compressed to 2 atmospheres of pressure. That means the heat of the air has largely transferred to the water, and because it is now compressed, as it expands back to 1 atmosphere of pressure, it cools. (Essentially, the active molecules that contain the heat go further apart.) Much of the moisture is also removed, because during the compression phase, the dew point of the compressed air goes lower than the temperature of the water in the trompe fall.

An eductor does something similar put with negative pressure. Railroad cars used to be air-conditioned with live steam through use of an eductor. Efficiencies are horrible, but it does work.

If your creek is pretty flat, you would have to pump the water up to make a trompe. The water would have to be relatively clean as well, as the air is "washed" with it.

As TnAndy pointed out, delta-T is the critical part of most energy systems. There is no free lunch. For air to be cooled a certain amount, a fixed amount of energy is required. Generally, a creek won't supply enough of that energy.


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## artificer

Industrial chilled water cooling uses water cooled to 45degF to 55degF. The higher the initial temp, the more cooling coil you need. So, the question is... what is the max temp of the water from the creek? Anything over 60degF is going to be too hot. Spring fed 55degF will work, but you will have to get a proper chilled water coil. Most of the industrial coils can be purchased with up to 12 rows of tubes.

You can find websites with cooling calculators on them. You need to know how cool the source water is, how much cooling you need, what kind of airflow your heater/blower has. You're probably looking at $500 for just the chilled water cooling coil.

After you find what you need for the coil, then you have to design the rest of the system. You need a pump thats big enough to handle the flow, high volume filter to keep the system clean, drain pan for condensate, and all the piping. Its not going to be a simple or cheap system, unless you scrounge a lot. 5 junkyard radiators stacked in a row for the cooling coil, that you get for a few bucks, could make the system workable.

IF your water is only 55degF, then you have a chance. Anything over that, and you'll have the problem the others have mentioned of cold clammy high humidity air. If you then run that air over a solar powered liquid desiccant system to dry it out... (actually, you'd dehumidify, then cool the air)

Michael


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## Harry Chickpea

Oklahoma ground temps are higher than 55, IIRC. Vermont was supposedly 52, but varied. There is a cave-like formation in Smuggler's Notch called the refrigerator. Snow and ice would get in over the winter and it was sometimes late July before it warmed up.

I once lived in a top floor apartment in Vermont with unmetered water and no AC. For a few days one summer, I attempted to run the shower on cold with a box fan blowing across it to reduce the temps. The water was cold - very cold. The experiment didn't work at all and I ended up buying my first window unit AC.


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## cmcon=7

60' up and 100' would require a large pump to be effective, a shallow pool in the shade close to the house with a large truck radiator,cheap bilge pump, and a box fan.
stick the radiator and fan in a window so it sucks air inside, the bilge pump pumps water from the pool and back, the water cools over night. this may provide some dehumidification and cooling, a way to start could be to set out a shallow pan of water in the shade and monitor it's temp for a few days to see if it is feasible.


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## copperhead46

It's really humid here, and the creek stays at 57 to 58 degrees, so it's starting to look like not such a good idea. Thanks guys for the good info, it answers many questions for us.


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## Jim-mi

The electric that the pump from the stream uses and the electric for the big fan blowing through the truck radiator will be well on the way toward the electric required for a window AC.
And as stated above the stream water probably is not cool enough to do what you want.

Beware; . .the salesman trying to sell you a very BIG window AC. . . .lots of electric.

So if you can use a window unit, Do your homework on AC btu output-- vers required electric input..........


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## artificer

I started this before I saw the additional responses, but I'll post it anyways...


24,000 btu/hr assumed cooling requirement
8.3lb/gal water
5degF temp change
4,800lbs of water/hr
80lb/min or 9.6gpm
60ft of head = 26psi

power needed at 60% efficiency is .19kw
Add a 70% efficient motor, and you need .27kw just for pumping
Add in a .25kw blower and you're up to .52kw's of power for cold clammy air.

Yes, its 1/5th of the 2.5kw a window AC unit needs, but how much is that worth? If you're off grid, and have to get more solar panels to power the AC unit, then it might make sense. If you're on grid, then the added expense and poor performance probably doesn't make sense.

Michael


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## silverseeds

you might not need a pump beyond getting the water flowing. 

Im assuming your intending to cycle the water back to the stream right? If so and the water flows to a spot lower then where you take it from, it should flow on its own once you get it moving. 

Ive had water flowing through over 150 foot of hose, and it will flow on its own as long as im releasing it at a lower elevation then Im taking to from. the speed it flows relates to how much of a drop there is.


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## ||Downhome||

A ram pump would eliminate the need for power.

I like the solar chimney thing. maybe you could look into that.


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## silverseeds

60 feet is pretty big for a ram pump set up i think, but if that works in this situation you could gravity feed it back to the stream and youd need no electricity. that sure would be cool if the ram pump works for you!


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## Ky-Jeeper

Could creek water be pumped over the outside coil of a window ac for a more efficient way of removing heat? I know the ac unit coil would have to be relocated.


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## Harry Chickpea

Ky-Jeeper said:


> Could creek water be pumped over the outside coil of a window ac for a more efficient way of removing heat? I know the ac unit coil would have to be relocated.


This is one of those counter-intuitive things. The way motors are designed, they work to the same wattage unless they are under minimal load. I once was fooling around trying to get a full understanding of a pool pump, and discovered that the current draw was only slightly less when the pump was in full cavitation (essentially just moving around air rather than pumping water).

In an air conditioner, the bulk of the work is in shifting the refrigerant from a gaseous state back into a liquid state. The common term most people learn in high school physics is "heat of vaporization" The energy required to change the state of water from solid to liquid, or liquid into steam, is HUGE compared to the amount of heat required to raise the temperature from just above freezing to just below boiling. In refrigerants, the process is different but the core concept remains the same - it is the change of state between liquid and gas that does the work and requires the energy.

When you cool the coil on an AC you are cooling the already liquified refrigerant down a few degrees. When it does the change of state back into a gas, that gas will only be a tiny bit cooler - but... in some instances it can be just enough to create problems with icing, which reduces the efficiency.

Ground source heat pumps are designed a little differently to deal with the issue. With window ACs you might even see warnings not to use them below certain outside temps.

The overall effect of cooling the outside coil of an air unit is limited to improving efficiency by about ten or eleven percent. That is best accomplished by surrounding the coil with wet aspen pads, so that the evaporative cooling within the pads lowers the temperature of the air crossing the coil. Putting water directly on coils corrodes them and allow a build-up of schmutz.

As an aside, where manufacturers do something I don't understand is allowing for cooling of the compressor or scroll itself. I understand they need to be in cans, but if there could be lower temps within the compressor, via something like a water cooling system in an automobile, it should work more efficiently.


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## fantasymaker

copperhead46 said:


> We have a year round creed about 100 feet from the house and are wondering about using some kind of re-circulating system to cool with, have any of you done something like this ? If so, can you steer me to some sources for info, or please share your experience, thanks





artificer said:


> 60ft of head = 26psi
> Michael


Where did you get the 6o feet of head figure? 200 feet of pipe will offer a LOT less resistance than that.
My calculations show a head loss of less than one so less than a half pound of pressure using 2 inch Id pipe..


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## artificer

fantasymaker said:


> Where did you get the 6o feet of head figure? 200 feet of pipe will offer a LOT less resistance than that.
> My calculations show a head loss of less than one so less than a half pond of pressure.


It came from the post:


copperhead46 said:


> we're probably 60 feet up from the creek, hopefully someone will know where I can find all the info I need



60 feet up may mean 60 north of the creek, but to me, "up" means elevation, especially since they already said they were 100 feet from it.

Michael


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## fantasymaker

artificer said:


> It came from the post:
> 
> 
> 
> 60 feet up may mean 60 north of the creek, but to me, "up" means elevation, especially since they already said they were 100 feet from it.
> 
> Michael


But that UP is irrelevant the only thing affecting the pumping of water will be the resistance.
Well once they get the pipe Filled. 
Even though THEY may be sixty feet up the inlets and outlets should be at about the same level and that would be all that counts
Although Im not sure what effect going beyound the 32 feet of atmospheric siphoning will have....we may be both half right.


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## Harry Chickpea

I've been holding back waiting for someone else to point this out, but you cannot have a column of water higher than about 30 feet unless there is pressure involved. That is about the limit of suction pumps and after that the water weight will start creating too low a pressure at the top.

At sixty feet, a CLOSED system for heat transfer might work, but it would need no place for the water to escape back to the creek, and it would be less efficient.


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## fantasymaker

Why wouldnt a closed system return water to the creek? Why would it be LESS effeciant?


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## Ky-Jeeper

Not to be smart ----- or anything. It would return to the creek in closed loop only if there was a heat exchanger. Open would just dump back into the creek. Maybe I'm looking at this wrong. Since I have been serviceing industrial loop systems since 1987 I've never had a creek to deal with. Just cooling towers, open and closed tanks and pits, air to water, and water to water heat exchangers, and chillers. Someone shed some more light on this.


fantasymaker said:


> Why wouldnt a closed system return water to the creek? Why would it be LESS effeciant?


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## Harry Chickpea

Perhaps it would be good to separate the physics involved from the practicality of such a system.

From a physics POV, you are wanting to move heat. The original post was a question about a simple loop of water that would take the heat from the house, move it to the creek, and then the creek would make the loop colder and bring coolth back to the house, or to put it a different way, be in a low energy state able to absorb more heat energy from the house. The creek is 100' away with a vertical drop to it of about 60', and use of a small pump is implied.

With a loop of pipe, with a heat exchanger in the creek, and a heat exchanger in the house, and a small pump and a fill hole at the very top of the system, the concept is simple, elegant, and avoids a lot of pitfalls. If the creek water was about 35 degrees, it would work like a champ. The losses would be from friction loss in the pipe, pump inefficiencies, and pumping expanded hot water down, when it wants to naturally stay at the top of the loop. Overall, if the delta T is big enough, inefficiencies are negligible compared to alternate methods of cooling. The top heat exchanger would be below the dew point of the hot room air, and would be able to dehumidify it as well as cool it. A small fan (requiring a second motor) could assist the process.

The above is just about the ideal situation. The real situation is considerably different, but lets hold back a moment and talk about an open system.

In an open system where the outlet is at the creek, the water is pumped up 60' (We'll ignore pipe friction and horizontal movement.) Think of it as a well.

If we pump water up 5' and allow it to fall back to the bottom of the well within a pipe, the weight of the water on the pump-up side of the open pipe loop will just about equal the weight of the water on the fall down side. Once that cycle is established, the pump has very little work to do.

When we begin to lengthen the up pipe and down pipe, things go swimmingly up to about 20 feet. At about 35 feet, the weight of the water in the down pipe is enough that it wants to fall faster than the pump can keep up. By doing so, if it was a pure liquid incapable of phase change, it would create a vacuum at the top of the water column going back down to the creek.

Water is not pure and can change from liquid to gas. By the time it is at 35 feet and pulling down, air that is entrapped within the water separates out, and some of the water turns into a gaseous state. A "bubble" of sorts forms at the top of the loop.

At 60 feet, this bubble is about 30 feet in height. The pump now is working to try to fill the bubble, so is in essence pumping every gallon of water up 30 feet. The efficiency of the small loop is lost.

If instead, the loop is closed on the bottom, and the pump merely has to move the water from one column to another that is roughly equally tall, it still has little work to do. Since the water is under pressure, there is no worry about bubbles or a vacuum.

The other issues with an opening into the creek include sand, silt, fish, frogs, bugs, and so forth, all going through the pump. (I know about this first hand.)

The reason I said the closed system would be less efficient was limited to one concept and I wasn't clear. Sorry, this is the full statement I should have made: The transfer of heat would be less efficient. Dip a pipe in cool water and the water in the pipe will get colder, but that water will not be as cold as the cold water for a very long time. A heat exchanger improves the heat transfer, but it can never be unity or over unity. The water in the exchanger is always going to be a little warmer than the water in the creek.

Cost efficiency is the real issue, and that brings us back to the reality of the situation as described. Heat exchangers cost money. Pumps cost money. Pipes cost money. The power to run pumps costs money. (I know... RAM pumps. Price out a WORKING RAM pump and then price out an electric motor and pump from Harbor freight. Yes, you can make RAM pumps - IF you are a machinist and have the proper materials and tools at hand. I've tried to make one based on plans and it didn't work, even though I followed directions exactly. On a practical basis, unless someone gave you a RAM pump for free, the cost is still enormous.

Then we get back to the basics that the original idea would not work with the temperature of the creek water. That has been covered previously. The gain in efficiency of a compressor powered AC by cooling the condenser coil is minimal, as I also pointed out previously. On a cost efficiency basis, the system is a no go.

... and that doesn't take into account damage from spring flooding, ice, metal thieves, and vandals.

We pump water from our creek for household use. The equipment cost vs. the cost of hooking up to county water made it over a three year break-even point with county water at $25/mo. There would NEVER be a break even point for a system such as described. Gain from reduced AC costs would at most be on the order of $100 per year.
(10% increase in efficiency, and total yearly power costs for cooling at $1,000). Once you factor in equipment lifetimes, cost of maintenance, power costs to run the additional pump, and so on, it is a money waster.


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## Ky-Jeeper

Roof Sprinkler Cooling Systems


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## Harry Chickpea

copperhead46 said:


> It's really humid here, and the creek stays at 57 to 58 degrees, so it's starting to look like not such a good idea. Thanks guys for the good info, it answers many questions for us.


Actually, if those temps remain the same during August and September, and you are willing to burn wood every day or two, there is a possibility of a way to make it work. It still wouldn't be cost effective, but possible. Energy has to enter the equation somewhere, and a wood fire is sometimes a possibility.


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## fantasymaker

Harry I get ya now I was thinking of a system that was closed from the intake thru the loop but open at both ends of the creek.
You explained it perfectly.


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## fantasymaker

Back to the OPs problem ..Excess cooling costs. 
How about Digging a deep trench and running air pipes through there?
I'm thinking a loop that would be 20 feet deep 40 wide.
A total distance of pipe of 60 feet. Starting at the Intake side away from the house Id run 40 feet of perforated pipe then 20 feet of solid pipe. I d cover the pipe with pea gravel till the last 20 feet.
The idea being that the condensate would be able to drain into the pea gravel. and that you want the last 20 feet of cooled air to be in a air tight pipe.
The reason I went with 20 feet of depth is its about as deep as its handy to go with my track hoe.
Yes 60 feet is more than the theoretical maximum heat transfer distance but would allow for soil heating from the intake air.


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