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Solarguy2018

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Posts: 17
Reply with quote  #21 
Hi Greg

Would the best way to build a solar furnace be with PV or would you have other potential ways of creating heat

Thanks
Lyndsey

gbwillson

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Reply with quote  #22 
Lyndsey-

It would be quite inefficient to use PV to produce heat, but you could use PV to power fans blowing air through a solar air heater. A small collector could use 12v computer type fans. Although with a large collector it becomes more difficult as the airflow requirements can rather high, this is especially difficult when using small computer fans. There are PV powered attic ventilation fans that would move enough air, but they tend to be rather loud. Best suggestion would be to build a collector using household current to power a fan so you know the CFM requirements of your collector. At a later date you could experiment with using PV to power your collector with DC fans.

Greg in MN
Solarguy2018

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Posts: 17
Reply with quote  #23 
Hi Greg so the best way to build my collector would be to use aluminum downspout from somewhere like Home Depot or Lowe’s then put it all into a wooden frame?

Thanks
Lyndsey
gbwillson

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Reply with quote  #24 
Best way? There isn't really a BEST way. Every collector build can have merit. While you can use aluminum cans or downspouts for your collector, using window screen is less expensive than downspouts and easier to build than cans. In any case, the screen, or cans, or downspouts are placed inside a box, insulated, ventilated, and the heat is moved into your home.

Greg in MN
Solarguy2018

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Posts: 17
Reply with quote  #25 
Hi all

It’s been a little while since I posted
I am truly interested in finding opportunities to work with people in the chat group to learn how to make this project happen

Anyone willing to assist me with this would be greatly appreciated

Thanks
Solarguy2018
jezter6

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Reply with quote  #26 
There's a chat group?

tiggerboy

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Posts: 2
Reply with quote  #27 
I'am new to this site and I feel a that most of what you say is mostly correct, but most people are looking for low cost easily put together systems.
I firmly believe in the KISS (KEEP IT SIMPLE), but if someone wants to spend $100's of dollars and days of work building elaborate boxes so be it.
I look at the pictures on this sight of these systems and most have white reflective drapes or shades on their south facing windows ?.
I read on the FAQ being stated that a buildings  south facing windows already let in all the thermal heating available already. (UNTRUE) 
1  white shades reflect all the suns energy
2  even if the shades are removed the solar gain is greatly improved but not maximized.
Answer: the simplest improvement = heavy mil black trash bag maybe $.25 cents with pull string easiest, cut down both sides (you now have about 3'x 6' sheet with a sleeve at both end to insert a curtain rod in both ends. hang it back up on the wall hardware most windows already have attached (use rods that bent with 2 or 3 inch returns at the ends ) this lets cooler air down low to enter the space between window and plastic then exits at the top  .
Using two meat thermostats the differences is usually about 25+ degrees ,screening also is an added improvement inside the plastic
There are so many ways to improve what we already have, that's what ought be dicussed and improve instead of boxes of beer cans with pipes drilled into a house

I live in Florida right now @12.37 pm this date it is 58 degrees out-side and breezy, house was 66 @ 7.30 am. THree bedrooms with the window treatment are 80+ and with doors open and the fans on low ,its now 69 and should get up 70+ before sun-down so simple does work.

WHen the weather warms up for good it will take about 30 minutes to rehang the curtains, so 1 hour labor  $.75 cents plastic, existing curtain rods= warm house.
stmbtwle

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Reply with quote  #28 
Hi Tiggerboy welcome to the forum.

You are on the right track, but there's a reason for what we do.

The reflective drapes: They are drapes, they can be opened and closed at will.  The pictures you saw may have been taken in the summer, when the drapes were closed to keep the sun OUT. In the winter they would be opened to let it in.

Windows are relatively good solar collectors, but experience has shown that putting a solar absorber INSIDE the window doesn't accomplish much. The light/heat entering the window would normally be absorbed by the walls, floor, and furniture anyway, and this in turn heats the air.  A black plastic sheet or black screen will heat up the AIR in the room more quickly, but the furnishings will remain cold. It's pretty much a wash. 

Then there are aesthetics. Most of us have a wife or significant other who would take a REALLY dim view of us hanging plastic garbage bags in the windows, so that option is out for us (trust me).

The idea behind the "expensive" boxes and ductwork is to capture MORE heat than would normally be captured through the windows. In a way they're "extra" windows that we can turn on or off on demand. A great many of the members live in northern latitudes, where the homes are better insulated than ours and the usual windows are smaller, to keep the heat in, compared to our big Florida windows which can lose as much heat as they gain (which is why we have drapes).  

Here in Florida there's not that much call for solar thermal, as most of the time we have more heat than we want, and when we DO want it it's usually at night, when the sun isn't shining anyway.  You CAN build a system to capture the heat during the day and use it at night, but storage is expensive and complicated, and for the couple months a year that it is used it's simply not cost effective (been there).  

But keep at it... there is always room for improvement, and if you can invent a cheap solar COOLER you will have a gold mine. 





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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
tiggerboy

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Posts: 2
Reply with quote  #29 
Well since my garbage bag drapes don't seem to innovative , I remembered a PHD lecturer saying that running a/c supply lines thru the attic is assinine which it is. I came to the conculsion that my attic is just a big solar box not doing anything.  So I turned my a/c fan to on with main system on off, guess what, the air coming out of the vents after running awhile is putting out 80 +/- degrees today (that's with full sun and 64 out side.
So the next thing to figure out is how to have fan turned on/off when the attic gets warmed enough. I don't have that know-how so maybe if this is well received some one wiill sent me an e-mail with suggestions/ Thanks
Just checked again after 1 hour running with fan on  still 80 degrees @3pm this date
stmbtwle

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Reply with quote  #30 
An ordinary attic fan thermostat in the attic would do that. By heating the house you are cooling the attic, which is what attic fans are designed to do.    

You'll probably also want a regular thermostat in the house to turn the fan OFF when the house is warm enough to suit you.

I think you'll want a filter of some sort to keep out dust, bugs, etc.

__________________
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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