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jamieF

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Reply with quote  #31 
Dan if I'm understanding correctly you're suggesting this? hizer redesign3.png that would require a 3/4" 16' long and another 4' to go back down but should work.    The reason the original design had 2 1/2" going across as the inlet was because I have a bunch of 1/2" and I was hoping that would compensate for not being a 3/4"    although is there any reason 2 1/2" won't work?
hizer redesign4.png
<EDIT>   hmm think I've answered my own question.   the bottom one won't drain in my dual 1/2" returns.    and If I exit from the bottom not the top then I stagnate the top of return risers.

jamieF

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Reply with quote  #32 
OK so most cost effective for me ie. what I have on hand   would be the following I think 
hizer redesign5.png  yes having the return line outside of the box hurts but it's cheap compared to another 20' of 3/4" copper ($36 for 12 feet right now)   This change would require a few inches of 1/2" and likely a switch of some T's from 1/2,1/2,3/4 to 3/4,1/2,3/4  I like have enough of everything as is.


Garage_Hermit

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Reply with quote  #33 
Hello,

I don't think you necessarily have to slope the entire panel to the right, for drainback:

one problem I have read about with these hizers, is pipe *SAG*: the weight of water makes the pipe droop, so it forms a "trough" that won't drain.

Sloping the entire panel to the right might not necessarily cater for this problem (such as in a case where the amount of sag exceeds the gradient...).

Could I suggest leaving the panel dead horizontal, but "stressing" the center of the pipes upward by a half-inch or so, using clamps or a deadman: then each hizer has a high point in its center, thus ensuring not only that it won't droop, but that there are two negative gradients, one in each half of the hizer, so the water is obliged to run towards either the feed or the return line.

G_H

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jamieF

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Reply with quote  #34 
Well if I go with that bottom drawing sloping towards the return will definitely result in trapped fluid as the return will exit from the top of the panel.     I'll definitely need to work on making sure the lines stay with a constant slope back.    I wonder if the absorber plates will be enough to hold them in place or if I'll need to add a brace off of the bottom that will push them up.  I'll see how bad it is when assembled I guess.   I'll definitely pay attention for them during assembly thogh
jamieF

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Reply with quote  #35 

copper grid for the collector is built and undergoing pressure testing. It's connected to my garden hose and holding mains pressure at the moment.   I'd love to say no leaks first time  but that would be a lie.   One took a bit more solder to seal  and another took taking the fitting apart cleaning it up and trying again.    I've almost never soldered before and both were among the first few I did.  It got easier as I got further.

Sitting on the saw horses undergoing pressure.
[IMG_20150221_165859] 

the return outlet.  You can see the well for the temperature sensor on top.  The inlet is almost identical just the temp sensor it on the top of that header.
[IMG_20150221_165907] 

I'll leave it under pressure for a couple of hours then drain it for the night.   My wife strongly suggested I help around the house tomorrow meaning "stop messing around with that and do something useful."   I now know exactly where everything will end up so I can wire up the temp sensors for it though and get that run and tested.  After that it's time to build the box.  My old 2" polyiso is looking pretty beat up.  I'm really thinking I'll need to add the coroplast or some ply as a back to keep things looking nice and sealed up.

If I was doing this again I'd spend more money and build 2 4'x8's.   the 4'x16' saves money but a portable 4'x16' isn't the most portable and what a pain in the ass to work on.    When full of water it's damn heavy even to just shift.



<edit>  excuse the disaster that is my carport...  There's a never ending list of projects flowing through there with multiple underway at any point. <edit>

Garage_Hermit

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Reply with quote  #36 
Nice !
It is Very Encouraging (to me...) to see the state of your soldering for a newbie !

(er... that carport looks like it has a south-facing wall...) (say no more...)

G_H

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jamieF

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Reply with quote  #37 
nope the opening to the carport is perfectly south.  I bought this house almost entirely because it has amazing solar exposure.   road in front is perfectly south,   no major trees or buildings causing any shade on the front roof, slight slope up hill to the north....  

I was wanting it for gardening as my old house was on a north facing slope of a hill and it was frozen a month early and stayed frosty a month later the the rest of town.

Today because it was sunny heat gain from the front windows was enough to move the house temperature to borderline too hot and will keep the furnace from kicking on until tomorrow at 7am when it will run for an hour or 2 and then the sun will be warming things enough for it to kick off. 

Thanks for the compliment on the soldering.   It's like my welding.  Not the best  but not awful.
jamieF

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Reply with quote  #38 
I did a test yesterday.  you can see it in one of the pictures above. 

I took a 1/2" length of copper, placed it on a scrap piece of 2" polyiso and then stapled an aluminum fin to it.   It held pretty well so I was happy.  It spent the day sitting on the floor baking in the sun then last night temps got down to near freezing.      This morning I noticed that the expansion and contraction of the fin has wiggled the staples loose and the fin is on the verge of falling off.      So This means no stapling of the fins directly to the insulation.    I'll need some sort of backer in there to hold it all together.     I've been doing everything I can to avoid wood in the collector but a sheet of 3/16" ontop of the insulation to attach the grid to is starting to look inevitable.    I also happen to have a roll of really thin (think heavy tin foil thickness) copper sheet that I can put down on top of the wood.   That may assist in getting the heat spread evenly to the back of the pipes.


SolarInterested

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Reply with quote  #39 
Quote:
Originally Posted by jamieF
...    So This means no stapling of the fins directly to the insulation.    I'll need some sort of backer in there to hold it all together.     I've been doing everything I can to avoid wood in the collector but a sheet of 3/16" ontop of the insulation to attach the grid to is starting to look inevitable.

Gary from BuildItSolar uses a thin strip of flashing material as backing. This has the advantage of effectively doubling the thickness of the fins.

http://www.builditsolar.com/Projects/WaterHeating/Fins/Fins.htm

http://www.builditsolar.com/Experimental/PEXCollector/SmallPanelAirVsSilicone.htm

[SmallP11]

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jamieF

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Reply with quote  #40 
Thanks,    new test fin on pipe, stapled to flat flashing sheet and then the insulation is baking in the sun I'll let everyone know how it goes.  
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