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[DPRG] Solar still

Subject: [DPRG] Solar still
From: Ed Okerson eokerson at texasconnect.net
Date: Sun Dec 22 12:40:02 CST 2002


This sounds like the traditional solar heater.  What I was thinking of was
more of a "high performance" solution that would enable year-round
swimming.  I have one of the "bubble wrap" pool covers, and while it does
reduce evaporation it did practically nothing for warmth, not to mention
the pain in the backside of putting it on and taking it off of the kidney
shaped pool I have.  What I would like to do is be able to bring the
15,000 gallons of water in the pool to 85 degrees, even when outside
temps are in the 35-40 degree range.  I do not believe any of the existing
solar designs can do this.  Natural gas heaters can do that, but gas is
ungodly expensive here.  If I can get a system capable of doing this, it
would be possible to also extend the plumbing in such a way to use excess
capacity to heat the house.  How about converting an old satellite dish
with mirrors to accomplish this task?  What I was hoping to find were
formulas to help calculate how much heat I would get if I were to make a 6
foot, or larger still.


On Sun, 22 Dec 2002, Kipton Moravec wrote:

> Heating a swimming pool is much easier than the requirements for a solar
> still.   The temperature you need is much lower, so the quality of the
> heater can be lower (and cheaper).
> There are two components to pool heating.  1 Heating the water. 2 preventing
> it from cooling.  Most people concentrate on Heating and ignore the Cooling.
> In Michigan we were able to extend the season a month in both directions
> with a solar pool cover and no heater.  There are two kinds of solar pool
> covers.  One that looks like bubble wrap and the other that is denser and
> white, and not very thick.  1/8" or so.
> The Non-bubble wrap kind is a little more money, but lasts a lot longer.
> The idea is that in the fall and spring the days are warm, but the nights
> are cold.  The temperature at night drops the pool temperature faster than
> the day temperature can warm it.
> The pool cover also helps prevent evaporation which also cools the pool
> water.  There are pool chemicals available that help slow down the
> evaporation by putting some kind of invisible film on the surface of the
> water that makes it harder for the water to evaporate. I have heard people
> say it works, but I have not tried it.
> ==========================
> One site says the solar pool heater needs to be 50% to 80% of the surface
> area of the pool.  Using that as a guideline you can buy panels, or make
> them.
> The store bought panels are usually 4x8 or 4x10 plastic.  They have a big
> pipe at the top and bottom, and a bunch of smaller pipes connecting top and
> bottom.  The colder water from the filter goes in the bottom and out the top
> to the pool inlets.
> If you want to do it yourself you can use PVC pipe and paint it black or use
> irrigation hose (already black)  Both are cheap.  Calculate the surface area
> you need from the pipe you are using and you have how much you need.
> There are ways to make it better, but it adds cost.
> You can substitute surface area with reflectors.  Instead of say 3 4x8
> panels of pipes, you could have 1 4x8 pipe and 2+ 4x8 reflectors. (it is not
> 100% efficient so 1:1 is not correct. (That is what they have to do for
> getting higher temperatures.)  But then you may have to follow the sun with
> the reflectors to keep the sun on the panels.
> You can also put plastic over the pipes to trap the heat from the sun on the
> roof so more will transfer to the pipes.  I do not know how to do this so it
> is not an eyesore for the neighbors,  If the back of your house faces south
> this may be an option.  If the front of the house faces south the curb value
> of the house will go down.
> I don't know how it is in California, but if all the backyards have fences
> like here you could run the pipes / panels on a south facing fence.  It is
> not as efficient having it straight up and down, as opposed to a slanted
> roof, so you will need more surface area, but it is easier to get to and
> will not be seen as much by the neighbors.  If your south facing fence is in
> the shade then it will not work unless the leaves are gone.
> Kip
> ----- Original Message -----
> From: "Ed Okerson" <eokerson at texasconnect.net>
> To: "DPRG List" <dprglist at dprg.org>
> Sent: Saturday, December 21, 2002 6:11 PM
> Subject: [DPRG] Solar still
> > Sorry about the non-roboticcs post, but I remember some time back a
> > discussion here about solar stills.  As I recall, some were interested in
> > using them to smelt aluminum, or other metals.  Has anyone ever considered
> > using one to heat water?  I was thinking about an economical pool heater
> > design.  The typical solar pool heater only extends the swimming season by
> > a week or two, at a cost of a few thousand dollars.  If I am going to put
> > that kind of cash into a solar system, I want to swim a lot more than a
> > couple of more weeks.  Does anyone have any data on how to calculate the
> > potential heating capacity of these things?
> >
> > Ed Okerson
> >
> > _______________________________________________
> > DPRGlist mailing list
> > DPRGlist at dprg.org
> > http://nimon.ncc.com/mailman/listinfo/dprglist
> >

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