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jamieF

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Reply with quote  #41 
so I did a test of a flat piece of flashing behind the pipe then a fin on top stapled through both into the insulation.   That test piece hit -1 last night, was too hot to touch while in full sun during the day and then this morning I pulled it apart to see how well put together it was.    both pieces easily lifted off of the insulation.  That's not shocking.  The good news is both pieces are stuck together well enough I'll need to pull hard and risk tearing the fin.   At the moment I'm leaning towards just going with this approach as the silicon will help hold things in place and I'll be pulling everything together a lot better when doing final assembly.  


Tonight I finished wiring the temperature sensor harness for the collector and testing that it will in fact transmit the data down 90' of wire.     So that gives me a total run of 110 feet to the furthest sensor.  The harness has 5 sensors,   Return water temp,   inlet water temp,  left, center and right side of collector.   the last 3 will measure the temperature of the fins roughly center of the panel and about 18" in from the sides.   I figure between the 5 temps I should get a good idea of whats going on and be able to figure out when to turn on the pump easy enough.

Tomorrow's task is to get the long 90' of cable pulled,  some more heatshrink on the harness as I ran out and then I think I'll lay out the insulation and start making a box shape.  For now the collector grid will just be floating in place.  I still have more fins needing bent and then painted as my coil of flashing was raw aluminum....

Garage_Hermit

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Reply with quote  #42 
Quote:
So that gives me a total run of 110 feet to the furthest sensor. 


This is good news for me !

will be watching out for your feedback, as my (planned) longest is ... 100 ft  [smile]

G_H

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stmbtwle

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Reply with quote  #43 
On my water collector I did not fasten the flashing to the insulation, rather I spaced the collector off about 1/2".  I figured it would reduce heat loss out the back.  Whether it actually helps or not I can't say.
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gbwillson

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Reply with quote  #44 
Just remember that if you have two or more wired thermometers that each has to have wire of the same length. Otherwise the readings will be off.

Greg in MN[comp]
Garage_Hermit

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Reply with quote  #45 
I am wondering if rigid black Corpolast would not make a reasonable substrate for copper pipes ?

I have the 4-mm stuff, it is rigid like you would not believe...

and it takes drywall screws really neat (although I have not yet tried a pull-out test...).

If a long-enough screw were used, it would traverse the insulation and penetrate into the plywood backing, for example, making a strong attachment.


ADDED:

If not using plywood backing (I think that this is your case, from memory...), then a sandwich comprising two layers of Corpolast with a foam core might be a good, strong, lightweight way to go...

Since Coroplast is tough to bond, such an assembly might best be assembled by through-bolting through metal lathes etc.

G_H


@greg

Quote:
Just remember that if you have two or more wired thermometers that each has to have wire of the same length. Otherwise the readings will be off.


Not sure we are talking about the same thing !

Our references to "temperature sensors" means digital devices, operating over a network, using the one-wire protocol.  They are not actually thermometers, since they do not read temperature: they just pick up temperature information and send it some place, in digital form, so wire length is not really an issue per se: what counts most is the "network typology", meaning, how the network is configured (which, on the other hand, *DOES* pose certain constraints regarding wire length...)

More info here:  http://www.maximintegrated.com/en/app-notes/index.mvp/id/148

G_H



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jamieF

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Reply with quote  #46 
Thanks Hermit, I was just going to post that link.      I definitely don't keep wire length consistent.  on this harness it's something close to the following
90' wire, plug, 5' wire, s1, 3' wire, s2, 7' wire, s3, 7' wire, s4, 3' wire , s5  

Right now they're sitting on the floor of my office and I placed all 5 sensors within an inch of each other at and all the same height from the floor and at the moment the readings are 18.0, 18.0, 18.0, 17.94, 18.0  all in  C.  My other runs are even more radically different when it comes to wire lengths  and if they are slightly inaccurate we're talking less then 1/2 a degree C.      

   What makes a  difference is  the heat shrink on some but not on others.   Those with heatshrink have a delay in recognizing the temperature change.  We're talking a few seconds at most behind those without heatshrink  but I can see it when the temperatures update every second on my program.  

I really really like the ds18b20 and arduino combination for it's ease of implementation, cost and accuracy. 

For a coroplast backer I'd be concerned about it melting in the box.   I intend to stagnate the collector during the summer if my tank temp is high enough.   My small scale 2 sqft collector hit 103 C in mediocre conditions when stagnated. I'm thinking I'll basically make all of the flashing and piping one big piece that is loosely stapled into the box.  The inlet and return pipe also goes out the back of the box so it will help hold things in place inside a bit as well.  Then a few small spacers to keep things in place if needed.  


 
jamieF

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Reply with quote  #47 
Today the wire was pulled through the conduit and the  collector harness was tested in it's final location.  The missing heat shrink was added and it's all working just fine.  I'll haul it back inside to wait until the collector is ready for now. 

I also hauled my 2" polyiso sheets out and set them up in the carport.  I've split 1 of them so I have them laid out  as 4x4,8x4,4x4.  I'll use small pieces of down to pin them together and spray foam or silicon them into one large 4x16 sheet.  After that the 2x2 edge pieces can be cut and put into place.   Next step after that is to drill the holes for the sensors, and the collector grid and then fit all of that.  

The issue is I've run out of funds for awhile for this project and to finish the collector will require flashing for the edges, coroplast for the back and glazing...   It'll be a few weeks before I can even think about working on that stuff.     So luckily I've got a bunch of crap kicking around the house that I can continue work on.   I long ago put cinderblocks into the ground to mount the panel to so I'll build the stand and have that in place.  Also I have a coil of flashing and more fins are needed.   Related to that I was thinking of drilling and pop riveting the fin to the back flashing.  I can afford a box of aluminum rivets and have the gun and time...  It would put to rest any concerns I have of the staples letting go without a real backing.

Being a programmer the software is never done.  Tonight I tweaked the arduino code so that it only sends temperature changes to the webapp and not every single reading.  Also the current sensors now send their readings as well.   So the next step there is to get the webapp up and running again and add handling for the current sensors.   It will continue to be ugly for awhile most likely but I want my readings logging again.


Garage_Hermit

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Reply with quote  #48 
Jamie,

Glad to hear the gizmo is operational even if on standby [smile]
Quote:

"run out of funds for this project"
, I know the feeling...

This is when one quits shopping and rolls up the sleeves to tackle those long-ignored physical tasks like shifting rock, tidying up, doing MORE DESIGN...

G_H

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jamieF

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Reply with quote  #49 
I'm trying to save some  money and thinking about switching from aluminum flashing to steel stud as the outer case of my collector.   
 The construction will be .157" of coroplast, 2" of polyiso, 3/4" of copper plus any thing from the flashing fins.  so that works out to  just under 3" if my math is reasonable.  

In town I can pick up 26GA GALVANIZED TRACK 3-5/8X10' for $4 each which is far cheaper then the 10' aluminum L's I was going to go with.  3"x3"x 10' L's are $9 each and I'd need 2 per section.    I'm aiming for pretty but $18 for 10' loses to $4 for 10 feet when I need 40 feet worth.     I can probably take back enough bottles to cover the steel [wink]

That 3 5/8" stuf  would only put 5/8" between the fins and the glazing.    I'll likely be going with the suntuff which isn't flat so I think it will be 5/8" then 1 1/8" up and down.    I'm not sure if that's too close or not.  My original plan was to have 1" between fins and glazing but I was also hoping to go with twinwall at that point.   Budget has ended that idea.

The extra gap from the 2" to the top of the stud can easily be filled with a thin strip of polyiso. I was originally going to add a 2"x 2" border to the top but it can be 2"x1.5" or whatever it actually needs to be in the end.

Garage_Hermit

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Reply with quote  #50 
I think it would be possible to stack two lengths of stud - Solar Dan did this and it looked OK !
Solar USMC also used stud & I think it looks great - far neater than wood (for example)...

If you have the time & energy, post a drawing, it might help you, and it will certainly help us [cool]

Otherwise, why not go frameless: just Corpolast back; PIR insulation bonded (or bolted) to it; side longerons made of PIR board cut into square section.
Then fix more Corpolast down the sides, as side frame: these "slats" would be angled back over making an "L" to allow fixing to the rear Corpolast.

Then add the glazing module: Suntuff, trapped into aluminum U-channel for  example, or even
rubber hose pipe.
The wavy ends of the glazing are sealed inside an "end glazing bar" made of foam insulation, held in compression by any system you can think of...

Well,  was only trying to brain-storm you [biggrin]

G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
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