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SolarInterested

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Reply with quote  #11 
TNWillie this might be an interesting read for you:

http://www.builditsolar.com/Projects/Sunspace/sunspaces.htm#LowMassSS

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Both temperature rise and airflow are integral to comparing hot air collectors

gbwillson

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Reply with quote  #12 
TNWillie-

Dan's correct in that a heater inside the conditioned envelope of the house is ineffective since the solar gain has already entered the household. There are devices you will see online being sold that hang in front of a window. What they do is essentially intercept the sun's rays and concentrate them in one spot in the room, directly in front of the window instead of the walls, floors, and furniture. So if you were to be near the window heater, you might feel warmer, but the rest of the room will actually be colder. In addition, the room will cool off faster after the sun goes down since the one warm object in the room is right next to a cold window due to the greater temperature differential, so the heat loss will be faster.

Now if you were keep the sunroom doors closed and somehow duct the warmed air into the house... 

As far as how much actual BTU's your heater will produce the square footage of the unit is the key, so build as large as possible. A 4x8 2-screen will give you up to 5,000 BTU's per hour on a sunny day. That's what an electric space heater will give you, but the solar heater only costs a few cents, or free with a solar panel, to run all day. Whereas the electric heater can jack up your electric bill in a hurry! A large unit takes roughly the same amount of time to build as a small unit. Material costs are higher, but often has less waste since a lot of the materials used come in 4x8 sheets.

Greg in MN
TNWillie

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Reply with quote  #13 
Phew! Where do I begin to respond to the latest info presented?  That you guys have provided me with food for thought would be an understatement.
I bought a 2 x 8 sheet of Tuftex, a roll of metalized bubble wrap type insulation, 1x4 boards, plywood and screen today. Having read the last few responses, I'm tempted to return these matls and rethink the entire sunroom collector idea.
Greg, the sunroom doesn't have doors because the opening from the master bedroom is so large. None the less, it could be done to accomplish your idea of using the room to heat more of the house via ducting. I'll look into that idea further. A few yrs ago, I placed 2x6 panels covered with black cloth in the sunroom with the idea of creating some solar generated heat. IF I was successful, it was to a minor degree. No pun intended. I figured that an actual solar collector with a fan would be more efficient. That's one reason I wanted to do this project.
I like the idea of a sunspace located outside the south facing wall and will research that idea as well. Two issues that come to mind are 1) how close the house is to the property line. I'm guessing there isn't much allowable space left, if any, to build within the code specs. and 2) Whether or not there are two soffit vents on that side of the house that lead to the crawlspace under the living room. I know there is one but unsure of an additional one. If so, and I have the room to build, I'd be able to run the ducting through the vents and cycle air through existing vents in the floor. I'll be checking on that the next time I visit there.
Now, I think I'll call it a day and sleep on all the info that has been posted.
THANKS guys!
Willie in TN

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I believe that common sense has become so uncommon that it should be considered a super power. Funny, I agree, but pretty sad too.
TNWillie

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Reply with quote  #14 
Well, having given a lot of thought to everything that has been posted on this thread, I have another question to ask. Simply put, would it be wiser to hang black cloth panels on the walls of the sunroom that face the windows? If so, I could also cover the floor of the sunroom, which is carpeted, with black cloth as well. If I went this route, a couple of box fans on timers suspended in the doorway would move the warmed air into the master bedroom.
This idea would be far easier and probably cheaper than building an indoor collector.
I look forward to your comments, one and all.
Willie in TN

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I believe that common sense has become so uncommon that it should be considered a super power. Funny, I agree, but pretty sad too.
TNWillie

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Reply with quote  #15 
After all the responses I got, I was hoping someone would have commented by now.
Was it something I wrote or perhaps my choice of words?
I hope not and apologize if that's the case.

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I believe that common sense has become so uncommon that it should be considered a super power. Funny, I agree, but pretty sad too.
solardan1959

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Reply with quote  #16 
I had redwood colored walls but hung some black landscape fabric the length of the wall.  The walls already would get hot even before the sunspace was built but I think the darker walls helped .  I did not take any before or after measurements I don't think.  My sunspace just the other day was generating over 90 degrees in the room when it was zero outside, so yes it works very well.  Because it is on the back wall of the garage I have been very hesitant about adding vents to blow the air into the garage.  I'm sure there is a code against having the garage vents going into the sunspace and allowing the car exhaust to enter that space though it would be very minimal.
I would cover the walls if light colored but would probably leave the carpet alone.  Unless it is white, it will do a good job of absorbing heat as it is.
gbwillson

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Reply with quote  #17 
TNWillie-

Busy, busy, busy...

Any dark surface will absorb the suns rays and help keep these rays from bouncing back out the window. I'd keep any dark curtains or fabric away from the incoming windows and exterior walls to keep the warmed surface away from the cold surface. Remember, you are not gaining any heat than that which has already entered the sunroom. You are simply trying to capture the warmed air and possibly move it to another room. Any feeling of warmth might be negated by the breeze from the fan.

So, in "theory" a collector inside the sunroom would capture the most amount of heat, and if you could effectively draw your intake air from the bedroom(cold air) and replace it with the warm air from the collector you would have net gain. 

Greg in MN
TNWillie

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Reply with quote  #18 
Thanks guys. I bought some landscape fabric and rolled it out over the sunroom carpet earlier today. The carpet is a very faded light tan so it has to help. I also looked at the area on the South side of my house and was disappointed to find the neighbor's house blocks the sun from reaching the ground even in the least. I guess its just as well since there is only one soffit vent on that side anyway. The neighbors are really great so I can't see asking them to remove their garage to allow the sun to land where I need it.  Their place really wouldn't look good with it removed anyway.
My last hope is to determine when the sun arrives on my deck which also faces West. If its reasonably early, perhaps I could fabricate and install an outside collector on the deck. All things considered, its looking like a project for next yr, if at all. If not, I'll say my goodbyes before signing off.
Merry Christmas and Happy New Year to all and to all a bright and sunny tomorrow!
Willie in TN

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I believe that common sense has become so uncommon that it should be considered a super power. Funny, I agree, but pretty sad too.
billdad

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Reply with quote  #19 
Hello Willie, 
There is good advice and experience on this site. I gleaned much info here after I was about half finished with my unit. You can see it in users projects. My advice to new comers is "never make a soda/beer can heater". It works very well but is so labor intensive. I will never do it like this again! How is that for advice? 
I had dreamed of making one for 25 years and finally found the time and shop space to do it.
I designed mine to vent through a shop window so I didn't have to put holes in my new addition stucco. Also, it meets code in my area since it is not permanently attached to the building. I went with the steel stud top/bottom plates for the frame due to fire, weather, cracking and aging resistants. I considered an adjustable snap switch but opted for a standard off/on unit after brainstorming with others here. The standard snap switch works very well for me. I found a great selection of fans at Digi-key.com. I used a 12 volt computer fan so I could install a solar panel to power it in the future. More airflow is better. I had trouble believing this from other members here and undersized my fan. It still pumps out a lot of warm air to the shop but may be a bit small. I used an 80cfm 12v fan in a 4'x8' unit.
Welcome to the site and have fun with it!


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TNWillie

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Reply with quote  #20 
Thanks for the advice, the welcome and the suggestions. FWIW, I haven't given up on the idea of a solar heat collector. The biggest problem is that the sun's rays don't land on the western side of my house until about 1:00. That really doesn't provide much time for a collector to heat up enough to produce a worthwhile amount of heat. If you guys don't agree, please respond.
None the less, I see myself visiting the forum from time to time to see what others are up to. I've learned a lot in the short time I've been hear and will definitely be recommending the site to friends.

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I believe that common sense has become so uncommon that it should be considered a super power. Funny, I agree, but pretty sad too.
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