Using 50' roll of 3/4" Copper ,painted black, in enclos

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TheyCallMeDave
Posts: 45
Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Tue Jun 02, 2009 2:55 pm

Greetings. Im wondering if anyone has tried this specific approach to a Solar Collector for water ? I cant find any info for such a Collector online. How do u think it would work out by using a 50' roll of copper as a collector, then sending the heated water to a storage tank below utilizing a small pump ? Any thoughts, tips, or online resources would be MUCH appreciated. Thanks.


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flcruising
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Location: Florida Panhandle

Thu Jun 04, 2009 6:45 pm

Here you go neighbor, more information than you asked for, but lots to inspire.

http://www.builditsolar.com/
[color=blue]Aaron[/color]

TheyCallMeDave
Posts: 45
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Location: Northern Florida

Fri Jun 05, 2009 11:53 am

flcruising wrote:Here you go neighbor, more information than you asked for, but lots to inspire.

http://www.builditsolar.com/
Aaron, Thanks for the site. I looked thru the whole thing, but nothing on using a roll of copper IN the actual solar collector that id place on the roof. I think it would work quite well if i took a 60' roll of 3/4" id Copper and painted it flat black and had it fastened to sheetmetal also painted flat black using triple pane glass on the top . (Under the sheetmetal would be 2" of styrofoam then 1/2" plywood ). Ill be buying a new electric water heater since i need one anyway...and using it as my Solar Storage Tank while keeping the heating elements as a backup. Im going to plumb the water from the Solar Collector into the Drain Valve and T&P Valve openings of the water heater ; ill still use a T&P valve but have it in a Tee right next to the water heater , and same with the Drain Valve. Ill be using a Groco CB-20-BB 12 vdc Circulating Pump which only uses 34 watts of power which will get from a couple of deepcell RV Batteries I have ; each night the Batteries will get a trickle charge for 8 hours while the Pump is off --- both pump and Battery Charger will be on Timers.

Have you considered going solar for your hot water needs ? SInce i live by myself, i KNOW it is going to easily meet all of my hot water needs . I figure payback will be approx. 1 year on this project. No sense in giving the money to CHELCO is there ?!

I have a rough idea where you live. Nice house. Is it a manufactured house ? Doesnt look like it.

David.

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flcruising
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Fri Jun 05, 2009 4:42 pm

Here's another link. I thought that site might send you to this one, but I guess I found it through Google.

About 3/4 of the way down the page is a setup similar to what you are describing, with the exception being that they used polyethylene tubing. Copper would provide better efficiency, but it is definitely more expensive.

http://www.1887brand.com/070613.htm

This guy compared Copper and PEX collectors, and concluded a difference of only 14% in performance. Unless you have the copper on hand, I think that you would be just as well off going with the cheaper material.

http://www.builditsolar.com/Experimenta ... lTests.htm

I have seriously considered going solar. I want to start off simple though, with just a batch setup using a black painted tank. The setup/controllers required for a DIY intelligent system just makes it seem like a huge leap on my part instead of baby steps that would more likely make it a reality. If you need a hand on anything, let me know, cause it would certainly inspire me to get going with it myself if I actually had you as a guinea pig. :P

BTW, thanks for the complement. Yes our house is a manufactured. We paid alot, got exactly what we wanted, just not exactly where we want it.
[color=blue]Aaron[/color]

TheyCallMeDave
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Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Fri Jun 05, 2009 6:50 pm

flcruising wrote:Here's another link. I thought that site might send you to this one, but I guess I found it through Google.

About 3/4 of the way down the page is a setup similar to what you are describing, with the exception being that they used polyethylene tubing. Copper would provide better efficiency, but it is definitely more expensive.

http://www.1887brand.com/070613.htm

This guy compared Copper and PEX collectors, and concluded a difference of only 14% in performance. Unless you have the copper on hand, I think that you would be just as well off going with the cheaper material.

http://www.builditsolar.com/Experimenta ... lTests.htm

I have seriously considered going solar. I want to start off simple though, with just a batch setup using a black painted tank. The setup/controllers required for a DIY intelligent system just makes it seem like a huge leap on my part instead of baby steps that would more likely make it a reality. If you need a hand on anything, let me know, cause it would certainly inspire me to get going with it myself if I actually had you as a guinea pig. :P

BTW, thanks for the complement. Yes our house is a manufactured. We paid alot, got exactly what we wanted, just not exactly where we want it.
Thanks Aaron for the sites. The collector they used on the Farm was pretty lowbuck..yet it yielded a very good return, so, im very encouraged as to how my setup will work and pay for itself . I can buy a 60' roll of 3/4" id Copper for $130.00 which i dont mind paying ; id be leary of using plastic tubing as its not going to stand up to extreme heat when the circulating pump is dormant. In fact, one article i read indicated theres a good chance of actual boiling taking place in the collector on hot days when the sun is out and no water circulation. I see they used 400' of Polyethylene Tubing ..but then again they were trying to have enough hot water for a large family. I have a good feeling that using 60' of wound single layer Copper Tubing as a Collector , painted ultra flat black, securely fastened to sheetmetal also flat black, and triple pane clear glass .... will be more than enough for my 30 gallon Water Heater . Im going with simple controls using a Water Heater bi-metal Thermostat set at 110 f. to activate the 12vdc circ. pump. Ill install a checkvalve in the system so I dont loose heat from the Water Heater back to the Collector at night / and on cloudy days.

I wont be starting this project till winter as i have alot of other more pressing projects to do around the house , plus, its soon to be unbearable up on the roof.


TheyCallMeDave
Posts: 45
Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Sun Jun 07, 2009 2:10 pm

TheyCallMeDave wrote:Greetings. Im wondering if anyone has tried this specific approach to a Solar Collector for water ? I cant find any info for such a Collector online. How do u think it would work out by using a 50' roll of copper as a collector, then sending the heated water to a storage tank below utilizing a small pump ? Any thoughts, tips, or online resources would be MUCH appreciated. Thanks.
I finally found someone else whos done the Copper Roll thing : http://www.ehow.com/how_4669902_solar-h ... n=yssp_art

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flcruising
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Fri Jun 12, 2009 1:12 pm

That looks easy enough Dave. Most rolls of copper come precoiled in flat boxes, so setting it in a frame should be real easy too.

Here's the one I'd like to try.

http://www.byexample.com/projects/curre ... collector/
[color=blue]Aaron[/color]

TheyCallMeDave
Posts: 45
Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Fri Jun 12, 2009 4:12 pm

flcruising wrote:That looks easy enough Dave. Most rolls of copper come precoiled in flat boxes, so setting it in a frame should be real easy too.

Here's the one I'd like to try.

http://www.byexample.com/projects/curre ... collector/
Yes...i saw that project awhile back. What im going to do with the roll of copper is solder it to the metal plate that its going to sit on to get conductive heat as well as radiation heat from solar rays. Ive decided to go with a 50 gallon electric water heater/storage tank because down the road , Im going to want to try space heating my Mobile and will need a larger tank (plus the addition of another 50 gallon tank too) . I just had a drop ceiling grid put in my cathedral ceiling living room and im in the process of putting in R30 batt insulation above the lay in ceiling tiles -- it should drastically cut down on heat gain and heat loss which should reflect in lower Chelco bills !

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flcruising
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Fri Jun 12, 2009 5:01 pm

So you're going to solder the copper coil to plate copper? You would need a pretty thick plate to have the 'heat sink' mass neccessary to gain efficiency and prevent your flat plate from deforming.
[color=blue]Aaron[/color]

TheyCallMeDave
Posts: 45
Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Fri Jun 12, 2009 7:06 pm

flcruising wrote:So you're going to solder the copper coil to plate copper? You would need a pretty thick plate to have the 'heat sink' mass neccessary to gain efficiency and prevent your flat plate from deforming.
Ill see what i can come up with. Otherwise, ill fasten it down some other way to where it makes sufficient contact.

roongee
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Sat Jul 11, 2009 8:59 am

flcruising wrote:So you're going to solder the copper coil to plate copper? You would need a pretty thick plate to have the 'heat sink' mass neccessary to gain efficiency and prevent your flat plate from deforming.
well that's right..thanks for the info


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Copper sinks
Last edited by roongee on Tue Jul 14, 2009 3:24 am, edited 1 time in total.

Gary Gary
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Sat Jul 11, 2009 8:12 pm

TheyCallMeDave wrote:Greetings. Im wondering if anyone has tried this specific approach to a Solar Collector for water ? I cant find any info for such a Collector online. How do u think it would work out by using a 50' roll of copper as a collector, then sending the heated water to a storage tank below utilizing a small pump ? Any thoughts, tips, or online resources would be MUCH appreciated. Thanks.
Hi,
If you are going to solder the copper coil to a metal plate, then I think it should work well. This is a lot of soldering -- my limited experience with soldering copper tubing to copper sheet is that unless you have quite a good clamping system, the sheet tends to wrinkle up as you solder.
You need to get a fairly continuous solder joint, as most of the solar energy is going to be absorbed by the metal plate, and you have to provide it a good path into the copper tubes.

If you bend the copper coil into a serpentine path going down the sheet in such a way the the tube always slopes down, you would be able to use a drain back system for freeze protection -- otherwise you will have to use a closed loop with antifreeze.

I've been building my collectors like this:
http://www.builditsolar.com/Experimenta ... lumCol.htm

They perform within 4% of a collector using copper tubes soldered to copper sheeting, and they are easy to put together.
http://www.builditsolar.com/Experimenta ... lTests.htm

Gary

TheyCallMeDave
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Location: Northern Florida

Sun Jul 12, 2009 3:24 pm

Gary, Thanks for the tips. Even if i cant solder the copper roll to the backplate, I think its still going to get extremely hot being painted flat black. Since i want a very slow flow of water thru the copper roll, im now thinking of going with 1/2" OD copper instead of 3/4" OD . But ill increase it to 3/4" once out of the collector.

Gary Gary
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Sun Jul 12, 2009 7:45 pm

Hi,
Almost all of the solar radiation coming into the collector is going to be absorbed by the metal plate, not by the copper tubing. Unless you have a good heat transfer path to transfer the heat from the plate to the tubing, I think that you won't have a very efficient collector.
The absorber will get very hot (because the tubing is not taking the heat away), and the hot absorber will just lose a lot of heat out the collector glazing.

On the flow in the tubes, most places recommend about 0.04 gpm per sqft of collector. If you run it too much less than that, then again, the plate gets very hot and loses a lot of heat out the glazing.

The most efficient collectors have have good heat transfer from absorber to tubes, and run enough water through the tubes to keep the absorber near the temperature of the storage tank water.
The hotter a collector runs, the less efficient it is -- you can see that by using this calculator:
http://www.builditsolar.com/References/ ... c.htm#efic

For example, if you run it with 40 F outdoor temp, and 110F absorber temp, you get an efficiency of 64.5%, but if you raise the absorber temp up to 200F, the efficiency drops to 44.7%.


Gary

TheyCallMeDave
Posts: 45
Joined: Fri May 29, 2009 6:37 pm
Location: Northern Florida

Sun Jul 12, 2009 8:39 pm

Gary, Something tells me that Ill have plenty of heat absorbtion thru the copper roll , when you consider the writeup in the Build-it Solar article of a guy who used just black polyethylene 3/4" coiled pipe on the top of his garage and measured an exit temp. as high as 150 f. + from running cold water thru it at normal water pressure . The Collector box ill be making is going to have triple glazed clear windows to boot. My real concern is one of OVER-heating . Dave.

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