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jjackstone

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Posts: 62
Reply with quote  #1 




End View.jpg 
End view.


Full frontal early.jpg
Full frontal.

So I built this thing a couple months ago pretty much as cheaply as I could. I bought three 1” x6” x 8’ boards for the frame. Already had some backing material, insulation, and glazing. The glazing was not top quality. It was just 6mil plastic shower curtain that I caught on sale for $5 a curtain a couple years back. Two of them overlapped worked just fine for this project. I did buy what I consider reasonably expensive 4” aluminum flex dryer duct to act as my collector. Went through three cans of spray paint for the back of the box and the first bit of flex duct. Cut two 4” holes in the same end of the box to attach more duct to get air in and out of the house. Slapped it all together. Used bathroom sealant along the edges of the box to attach the shower curtains so at this time no additional holes needed to be made. Being my first experiment I wasn’t worried about perfection. Just wanted something to play with. Added a piece of ¾” x 10 ft conduit to the back so it would be easy to rotate the box to the sun. Mounted it on a couple old jack stands that had been converted to cable pull stands. Picked up a 4” fan as my blower.  Also you can probably see in the photo that I only had the box half full of collector material to begin with. Ran it this way for a couple weeks and it did alright. Nothing great. Warmed a 250 sq. ft. bedroom about an extra five degrees over the rest of the house on 55 to 65 degree days outside. Closed the door to the bedroom to help separate it. This room does get better direct sunlight than the rest of the house so that helps a little too.

Completed Upgrade.jpg Current status. Still need to shorten the duct from the collector to the house.


  Flex Hangers.jpg
Flex hangers.

Eventually I wanted better performance. So I added another 50 foot section of flex and installed some SunTuf. It is sealed better now. I used one type or another of foam window seal all around the border. The extra length of flex definitely slowed the air flow so I have a 6” blower on the way right now. Originally the flex was just kind of laying there. I tied it up at each end so that it was stretched out for better air flow. It appears that the heater is working better because the same room is showing a higher heat increase now. Although that is based on one day only. We have had intermittent rain here ever since I upgraded the system last week. So I don’t have a large data set yet. I have a Kestrel 200 for measuring temp and air flow. The air flow is really terrible. Looks like about 25cfm. 250 – 300 ft/min out a 4 in duct. Temperature is fine though. I‘ve had as hi as 150 degrees coming out at this flow rate with low to mid 60 degree inputs. I expect the 6 in blower should help bring down the output temperature and heat the bedroom much quicker.

JJ





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gbwillson

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Reply with quote  #2 
Kinda hard to move enough air through 4" ducts with so many bends and ribbed tubes. Two fans, one at each end, may be better than a single, powerful fan.

Greg in MN
KevinH

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Posts: 557
Reply with quote  #3 
Welcome to the group JJ.  There is a lot satisfaction feeling the hot air coming out of your first collector build.  You are in the right place to learn more for any future builds you do.

I also saw your post on reflectors.  I use them on my collectors and have a couple reflecting into windows.

As Greg mentioned, the serpentine flow creates some tight bends that can be restrictive, requiring a stronger fan.  Also, you can get better heating with flat black paint.  My last two collectors used 3" aluminum flex duct with the tubes in parallel (plenum at each end).

Kevin H
MN
jjackstone

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Posts: 62
Reply with quote  #4 
Yeah after doing the calculations even with a 6" fan I don't expect this build to perform especially well. Just something I could put together really quickly. Eventually I'll test a ZP model and I was thinking of a screen model with an aluminum honeycomb core sandwiched between two screens to increase collector surface area. The aluminum honeycomb is a little expensive though so for a near zero dollar build that won't work so well.
JJ

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gbwillson

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Reply with quote  #5 
JJ-

There has been a bit of discussion about adding a third layer in the middle of the screen gap, but it has always been a middle layer of screen, which is cheap. The trick is how to hold the middle layer of screen without its frame partially blocking the screen gap. So a thin frame or some other system to hold the screen tight and in place would be needed. 

Greg in MN
jjackstone

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Posts: 62
Reply with quote  #6 
Has anyone on here, that you know of, just taken a couple of old screen doors or window frames and just popped them into a box to use instead of making a separate frame for the screen material?
JJ

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stmbtwle

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Reply with quote  #7 
Someone probably has but I haven't heard about it. To do so you would have to make the collector to fit the screen. Seems easier to build the box first to whatever dimensions you like, and make the screen to fit. Screen is cheap, twinwall and plywood isn't.

Doors are a rather odd size, making a collector box to fit them would probably result in a lot of waste, unless you have a good supply of doors...


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

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Posts: 62
Reply with quote  #8 
How annoying. I received the 6" blower five days ago. I have had 4 good hours of sunshine since then. That was two days ago. the output is better. Best I could measure is about 25% more heat transfer. Anywhere from 60-70 degree temp difference at a rate of about 40cfm. From the general consensus I guess I should be blowing around 90 cfm. Looks like at least two or three more days of rain before I see the sun again. [frown]  Don't know how you guys with snow can handle it.
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