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gbwillson

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Reply with quote  #11 
While it very well could be that a sunspace has the same efficiency as a collector, the sunspace has WAY more variables affecting performance. The size, depth, colors inside the sunspace, and furnishings, will all have an effect to some degree. While with a collector of a specific size and build, you can have a pretty good idea of the output. That is mostly due to the fact that many collector are built, and sadly, few sunspaces. If I had any space on the South side of my home, I'd opt for the sunspace every time.

Even if your sunspace doesn't add much heat or warmed air to the house, it will still warm the house wall behind the sunspace. It will also give you a nice cozy place to relax in the sunshine. 

Greg in MN

gregkn73

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Reply with quote  #12 
I intend to make it is a close to low thermal mass as possible. Lay insulation on the ground and to no glazed surfaces, no furniture and very few plants. Also I will paint black all the non glazed surfaces, except the walls of the house....I try to figure out what will be the best idea, to temporary cover the walls with something black. I red that Dan's idea for his subspace didn't work well
gbwillson

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Reply with quote  #13 
The thing about living in a frigid winter climate is that just being in the sunshine, out of the wind tends to feel very nice. And Dan lives in one of the coldest parts of the civilized world come winter in northern Minnesota. Every spring you will see people outside enjoying the sunshine when it's only 40˚F outside after a long, dark winter. No lie, but shorts, t-shirts, and the occasional bikini's worn by the co-ed's at the many local universities at such temps. The LOOOONG, cold winters where you get up and go to work in the dark and come home from work in the dark as well can really get you down. But the coldest days are also the sunniest! Years ago lived in a 100 year old house that had an uninsulated 3-season porch. The windows were leaky single pane storm windows. It was ice cold until I warmed up my favorite chair. But every sunny weekend morning I would sit out there and read the newspaper. 

I like the temporary black wall idea, and think fabric would be nicer than any sort of plastic. Maybe a small heated blanket or throw would be needed until the space warmed a bit. But the point is you have extended your winter livable space, and might add a bit of free heat to your home at the same time.

Greg in Minnesota 
JohnGuest

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Reply with quote  #14 
I find landscape fabric works well as an absorber especially if you have an airgap behind it. The spunbond polyprop type will handle a stagnation temp of 80C (176F) without any problem.
gregkn73

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Reply with quote  #15 
Quote:
Originally Posted by JohnGuest
I find landscape fabric works well as an absorber especially if you have an airgap behind it. The spunbond polyprop type will handle a stagnation temp of 80C (176F) without any problem.

This is what Dan has done, with no good results. I still wonder why?
gbwillson

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Reply with quote  #16 
If no air is passing through the fabric, or in close proximity to the fabric, there won't be much heat transfer. Same thing if a screen collector has the screens laying flat against the back of the collector. The dark surface simply reduces the rays reflecting back towards the glazing.

You could try leaving a small gap between the fabric and the wall and have the air flowing in this gap behind the fabric. This would allow the air to pick up the heat absorbed by the fabric. 

Greg in MN
JohnGuest

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Reply with quote  #17 
It looks like Dan had the landscape fabric attached directly to the wall so the heat transferred into the wall mainly via radiation and conduction. With a reasonable air gap, you`d gain upward convection between the wall and fabric.
gregkn73

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Reply with quote  #18 
Thanks again Greg and John, for the useful info. I am gathering materials to start making the subspace. The fan I am going to purchase is 935h3/h and he had a 20cm pipe diameter. It will be placed into the subspace, pushing hot,air into the house. Because I am going to open holes in my bacement made by cement, I will open one 20cm hole for the pipe transfer air into the house, the other hole moving air from passively from the house to the subspace, shall I make it exactly the same dimensions or it doesn't matter if I make it little smaller?
gbwillson

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Reply with quote  #19 
935h3/h? Is that the free-air rating of the fan?

I would wait on the purchase of a fan until see what the conditions are within the sunspace before you make a fan purchase. I'm sure you have a spare fan or two you could use in the short term. Waiting on the fan purchase might also change the size or capacity of the fan needed. Which in turn could change the size of the hole in the wall.

Greg in MN


gregkn73

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Reply with quote  #20 
935m3/h=550cfm, an inline centrifugal fan. in any case my question is if the inlet hole where the fan actively push air through the duct, should be the same dimensions as the outlet hole, where air passively returns in the sunspace? Does  it matter the latter one , be a little bit smaller?
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