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Scott Davis

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Reply with quote  #1 

Welcome to the SimplySolar forum!  We're delighted to have you with us!

You've just joined a very friendly group of solar hobbyists and enthusiasts.  There are even a few professionals here!  We thoroughly enjoy discussing the hobby / art / science of solar, helping new folks get started and connecting with others who share our interest and passion!

SimplySolar is all about brainstorming and sharing ways to implement solar heat easily and inexpensively, that the average homeowner, who may not be much of a "do-it-yourselfer" (like me), can use to put money back in their pockets, green back in the environment and have a lot of fun along the way!

Regardless of the systems we install and our individual "do-it-yourself" abilities, we encourage design approaches that are easy to build and work well.  Collectors with attractive appearances, as well as low profile, neighborhood friendly or "stealthy" designs are also encouraged.  Solar can integrate well into any neighborhood.

Brainstorming new ideas is a primary theme of our group.  We are all learning from each others projects and experiments.  Everyone is encouraged to think outside the box, experiment and share their ideas!

With that in mind, a positive, encouraging, open and considerate spirit is essential!  Not every idea is going to work out, but it might lead to a brand new idea that will.  If a thought is offered that doesn't ring correctly to you, please be sure to offer your alternative view and the reasons for your belief in a positive and friendly way.  Our group will be much better for it and we all benefit by our collective care.

Along that same theme, posts on macro solar issues and political content are not allowed.  We have plenty to talk about, brainstorming our solar projects, trying/sharing experiments and helping new folks get started with solar!  Commercial links are only okay if they are used in the context of an ongoing DIY discussion.

If you are new to solar, you've just joined a great resource!  All of your questions, no matter how basic, are very welcome here.  There are lots of folks on this group who are very enthusiastic about solar and eager to help you.  One idea leads to the next and the sum of everyone's thoughts will be a great help thinking through your project.

If you have already built some solar projects, please tell the group what you have been doing and how it is working for you.  Pictures in your posts really encouraged here.  As always, a picture is worth a thousand words and takes much less time to absorb!

Most of all, jump in, participate and have fun!  In addition to all the other great reasons for solar, building solar projects and sharing ideas is a fantastic pastime!

One suggestion.  If you have a lot of questions, for the best input from the group, try to avoid a really long narrative in a single post.  Instead, break your questions down into manageable, bite sized chunks.  You'll get a lot more good information and ideas that way!

If you know others that may be interested in having fun, saving money and helping the environment with solar, please tell them about our forum!

Thanks again for joining the Simply Solar forum!  We are very glad you've joined us!

Warmly,
Scott

p.s.  For more about me, please visit: http://www.n3fjp.com/whon3fjp.html


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alvin_the_writer

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Reply with quote  #2 
Many thanks to G. Scott Davis for his "Love for his Neighbor" = (Me) .  This whole forum has the Imformation I need to allow me to continue My Life on Planet Earth.  I saw one of your Solar Collector Videos Then many days later I still remembered your video and was comparing others to the way you presented yours and thought I must learn more about "Scott Davis" and I did find You. I am very humbled to find a Man who devotes his time to help other Americans as the Forum and its mision to reduse our dependence on foreign countries. Now is the Time for we th People to rebuild America with Solar energy.  Again Thank You G. Scott Davis for leading us ~ ~ etc.
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jjmccoy

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Reply with quote  #3 
Thank you very much for the welcome, I'm new in this, but I would like learn too much here, again tank you and lets go to start!

From Mexico

Julian[smile]

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JJ
Scott Davis

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Reply with quote  #4 
Thanks so much for your very kind words Alvin and Julian!
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sjlsr

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Reply with quote  #5 
I want to build a 12ft long by 3ft high down spout solar heat unit for the south side of my shop.  Where is the best place to get construction plans?  In the pictures I've seen it appears the spouts have space between them and I haven't been able to find the explanation for that.

SJLSR
Garage_Hermit

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Reply with quote  #6 
Hello,

I guess a DS (downspout) person will answer this more fullly, but basically the idea is, having air space between the downspouts means that said air absorbs solar heat more quickly than plain metal (even aluminum): that is because air has a lot lower specific density than metal (and only a quarter of that of water, for example).

So the idea is, the air heats up and then conducts heat into the metal of the nearest downspout.

Because the downspouts are separated by air, there is a greater surface area of metal for the air to touch...
This is called, "wetted surface".

This might sound contradictory - less metal, therefore more metal, but the reasoning is simply arithmetic:

If your collector is 36 inches high, and your downspout is five inches, then you could place 7 DS side by side, for sure.

You therefore get 35 inches height, times the length of DS, = total metal area.

If you use one less DS, then you get 6 DS of height, = 6 x 5 = 30 inches of DS height,
PLUS
the horizontal tops and bottoms of six DS;

So now imagining the DS is also 3 inches WIDE, then you ge to add
6 inches of DS width, for each DS, because the DS roof is 3 inch wide, and the DS floor is also 3 inch wide, and they are touching hot air...

So for a foot of DS length,
in the first variant you would get 12 x 35 = 420 square inches of metal
and in the second variant you would get 12 x 30 inches = 360 + (12 x 6) = 72 totalling  432 square inches of metal.

====

Putting it simpler:
a hard-mounted DS gives you a surface area of LxH
whereas a DS in air gives you a surface area of L x H + (2 x W)

So in our example, using one less DS (six, instead of seven) gives 3% more metal area...

Less DS = less cost... (around 16 percent less).
========
Against this cost / heat-density equation, you have to offset actual airflow...

For a given airflow through the collector, six downspouts have to manage more pressure, more density, = more velocity.

You would offset the pressure issue by increasing the size of the end plenums (which has the added effect of decreasing the length of DS material, thus more savings from the purchasing viewpoint...)

You would offset the velocity issue by increasing the size of the fan (which would in turn lead to greater fan cost, greater power consumption...).

So all these factors have to be offsetted against overall system performance (amount of heat delivered, in BTUH, per cubic foot of throughput, per square foot of collector).

Whence the need for some careful thinking before investing in materials...

Welcome to the site, and good luck with your build !

Garage Hermit



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Scott Davis

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Reply with quote  #7 
Hi G_H,

Actually, the air in the downspout collector isn't particularly relevant.  Sunlight shines right through the air, striking the downspout, which causes it to heat up.  If there is spacing between the downspouts, something like aluminum flashing between, against the back wall, does a lot better job of conducting the heat to the downspouts than air would.

SJLSR, take a look at this video for how I built my downspout collector:

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JohnnyMac

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Reply with quote  #8 
Glad to be here. Scott this is a great site and info. I want to do a solar hot air project on my house in Buffalo, NY. I'm afraid of the solar hot water collector and freezing of the pex piping. During the night it gets cold enough to freeze the water in the collector, and the piping to the house has to be buried quite deep underground.
I will have lots of questions as time goes by
netttech

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Reply with quote  #9 

Welcome Johnny,

There's several ways to handle Solar Hot Water, freezing issues. I am using Anti-Freeze instead of water.

I'm pumping the heated AF thru pex radiant tubing under my floor.

There are drain-back systems also.

Solar hot air is the easiest to get involved with Solar heat tho. It's also the least expensive.

Ask away for all questions you may have.

Jeff
Central IL

JohnnyMac

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Reply with quote  #10 

Jeff, Thanks for the response. If you run the AF through pex do you have to be careful of not having it too hot? I think I read that too much heat can damage the flooring such as  Dry out and crack wood floor and sub-floor. How do you regulate the liquid temperature?

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