# DIY solar hot water system



## woodsy (Oct 13, 2008)

Any easy to read plans w/materials list out there ?
Looking at tieing in to existing 40 gal electric water heater. Will use PV panel to power DC pump.
Would be a year round cold climate type system @ 45 deg. latitude.
Have good southern exposure/orientation from rooftop. 
Craftsman by trade, carpentry, plumbing, electric, mechanical too.
Its a start...then solar electric pay as we go, add on as we go.
Thanks for the input


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## Kevingr (Mar 10, 2006)

Check out Gary's website. www.builditsolar.com Tons of info there.


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## wendle (Feb 22, 2006)

I recommend getting the book "Solar water heating" by Bob Ramlow. It's an awsome book with lots of explanations and pictures, very easy to understand. It talks about different types of systems along with pros and cons. 

http://www.arthaonline.com/bookpage.html

Good luck and please post your progress and experiences


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## SolarGary (Sep 8, 2005)

Hi,
Here is the one I am using:
http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm

We are at N lat 45.5 degrees, so we get a lot of cold weather -- the drain back system has done fine.
There is a collector version based on PEX-AL-PEX, and one based on copper pipe -- $4 and $6 per sqft respectively.

In terms of being less expensive than commercial systems (which seem to now run up the $7000 area), the storage tank, heat exchanger, pump and control arrangement are just as important as the collector -- this system tries to put together a whole combination that is less than $1K, but still uses high quality materials. 
As long as the vertical rise from tank to collector is not too large, you can use a PV driven pump on the system if you want to -- that's actually the way I have been running it the last couple weeks.

As Kevin says, lots more plans for other types of solar water heaters in the solar water heating section:
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

Gary


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## woodsy (Oct 13, 2008)

Thanks for the input everyone.
The budget is an issue for me and I like Gary's idea of keeping the cost to a minimum,
hence, trying to build as much of the system as possible myself.

Looks like I'll have my work cut out for me.
Great website BTW Gary, enough info there to get me going i think. 
I did build a gravity fed batch water heater back in the 80's, LOL.
I'm sure to be back with more questions.!


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## maxny (Aug 18, 2008)

I'm collecting parts and am going to build this one. It's very inexpensive. A friend of mine built one and it works well.

http://www.byexample.com/library/illustrations/batch_collector/illustration_bc.jpg/view


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## woodsy (Oct 13, 2008)

So, getting some of the terminology down, surfing around the web looking at and for various plans(freebies of course).
Starting with the panels, found Gary's info *very* helpful on construction of panels, thanks. Should be No problem here with building my own.
Found this panel diagram on Mother Earth News which is similar to Garys with a few exceptions.
I plan to take the sum of many plans and create my own for convenience and readily available materials.
Any particular reason the header pipes are 3/4" as opposed to 1/2"? Doesn't seem like a big deal either way?
Looking like it will be a two tank system now as our current electric HW 40 gal heater is due for replacement after 18 yrs. Will this older tank be suitable(life expectancy) for extra storage or will it start leaking in a few years?
The heat exchanger component of the system is still being hashed out but time is on my side as i wont start building the panels till it warms up in the shop in a couple months.
Also, will soldered copper joints hold up in the panel?


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## SolarGary (Sep 8, 2005)

Hi,
On most collectors the supply and return manifolds along the top and bottom of the collector are larger diameter than the risers. The idea is that the larger pipes will distribute the flow evenly to all the risers. It also lets you hook several panels together in parallel by just connecting the manifolds together.

The problem with larger diameter manifolds for homemade collectors is that the 3/4 by 1/2 reducing Tees are hard to find and very expensive when you can find them. I used half inch manifolds and arranged things so that the supply and return go to opposite corners of the collector (eg supply to lower right, return from upper left) -- this way the flow path length through each riser is exactly the same, so pressure drop should be the same, so flow should be the same. The panel performs well, so I guess it works. One thing I want to do is take the glazing off the panel and see if the surface temp varies over the panel, which would indicate uneven flow -- but, I'm not expecting to find a problem.

The limitation of the half inch manifolds is that it would not be a good idea to string together several collectors in parallel by just coupling the manifolds together. For a solar hot water system with a lot of collector area, the best scheme would probably be to use two side by side riser arrays, and connect the supply lines to the bottom outside corners of the arrays, and do the return from the upper inside corners of the two riser arrays.
I believe that this arrangement would work OK up to around 100 sqft of collector.


Did you look at the storage tank/heat exchanger I used? I think its the best feature of the whole system. The non-pressurized tank is cheap and easy to build, and they have a good track record dating back to the 80's -- when the liner needs replacing in 15 years or so, instead of throwing the whole tank out, you just put a new $50 liner in. The large plastic pipe coil heat exchanger has no track record at all, but (so far) has worked very well. Its also cheap and easy. Under most conditions its a 100% efficient heat exchanger because it holds so much hot water right inside the exchanger.

To me, the nice thing about this whole setup is that with the inexpensive collector and tank, you can afford to oversize both compared to the sizing used in most commercial systems -- this will get you a larger solar fraction with the ability to span several cloudy days. Our solar fraction for February in Montana was 98.5%.

Tank/Heat Exchanger:
http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm#TankHX
http://www.builditsolar.com/Experimental/PEXColDHW/HXPerformance.htm

System Performance:
http://www.builditsolar.com/Experimental/PEXColDHW/Performance.htm

Gary


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## woodsy (Oct 13, 2008)

Yes i checked out your entire system Gary, looks great, large capacity and great price too. I'll be looking it over some more.
Thanks for the help and plans, explaining the tube size question , just what i was looking for.
I'm figuring on making two panels for approx. 60 sq. ft. total.
Now to start gathering the material.


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## SnakeRiver (Feb 7, 2009)

Cool stuff! this gives me some idea for heating the critter spaces.


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## quietstar (Dec 11, 2002)

Gary..I have to say thanks for all the wonderful information you make easily available...Glen


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## SolarGary (Sep 8, 2005)

quietstar said:


> Gary..I have to say thanks for all the wonderful information you make easily available...Glen


Hi Glen,
You are most welcome -- some of the best projects on BuildItSolar came from people on this forum.

Gary


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## woodsy (Oct 13, 2008)

I've noticed some of the solar collector panel mfgs. mention small airholes in the box for ventilation to combat condensation in the panels.
I've been wondering about this as I build my panels. Any comments on this??
Making good progress on two of them btw. I figure there are about 150 pieces to assemble in each one of them including screws, fasteners etc. No small job but doable if you are handy and have some extra time.
I think the heat exchanger tank i will use is still buried in snow on the farm dump out back in the woods. A square galvanized bin of some kind that i've noticed in the past.
Will post a picture or two of my DIY panels soon, about two hundred bucks apiece for materials.


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## SolarGary (Sep 8, 2005)

woodsy said:


> I've noticed some of the solar collector panel mfgs. mention small airholes in the box for ventilation to combat condensation in the panels.
> I've been wondering about this as I build my panels. Any comments on this?? ...


Hi Woodsy,
I drill a small hole (maybe 3/16ths) in in the lower end of my collectors. It acts as a vent and drain hole (if something springs a leak inside).
I've never noticed any condensation in my collectors, but we are in a dry climate.
For me, the idea for the small drain/vent hole came from NZ Mike on the Solar Thermal forum -- he has been building good collectors for many years, and I tend to trust his methods.

Gary


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## woodsy (Oct 13, 2008)

Thanks Gary, sounds like a good idea.


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## woodsy (Oct 13, 2008)

Could someone explain the (1/2" sweat) just after the model number in this link.
Says the pump is for 3/4"+ connections, just a little confused on this
Also, my system is all 1/2", can I go from a 3/4" pump down to a 1/2" system without stressing the pump? It seems ok to go up but not down?
Thanks, having fun now...


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## SolarGary (Sep 8, 2005)

Hi Windy,
I believe that Taco offers all of these connections sizes and types to the pump inlet and outlet: "Connection Sizes: 3/4", 1 , 1-1/4", 1-1/2" CI Flanged or 1/2 Swt, 3/4" Swt, 3/4 NPT, or Union",

and that this particular one has the half inch sweat (solder) fittings. I believe that this means it will solder directly to half inch copper pipe.
Its odd that the picture shows a flanged fitting, but I guess they did not want to make separate pictures for each pump.

The downside of using the sweat fittings is that its harder to remove the pump once its soldered in. If you use the flange connection ones (like the one in the picture), then flange on the pump mates with a same size flange you mount to your half inch pipe, and the two flanges are held together with bolts -- there is a rubber gasket between the flanges to prevent leaks. This way, you can remove the pump without having to do any unsoldering. A union on either side of the pump would accomplish the same thing.

I don't see any problem in going from 3/4 at the pump down to half inch. The longer your half inch lines, the greater the pressure drop, and the less flow your pump will put out, but it won't hurt it. Here is the way the flow rate vs pressure drop in the pipes works out:
http://www.builditsolar.com/References/Pumps/PumpCurves.htm
So, this 006 puts out 10 gpm with no pipe resistance dropping to 5 gpm with 5 ft of water head pipe resistance.

These pumps are very rugged, just don't run them dry.

The $134 looks like a good price to me.
Gary


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## woodsy (Oct 13, 2008)

> SolarGary
> I believe that Taco offers all of these connections sizes and types to the pump inlet and outlet: "Connection Sizes: 3/4", 1 , 1-1/4", 1-1/2" CI Flanged or 1/2 Swt, 3/4" Swt, 3/4 NPT, or Union",
> 
> and that this particular one has the half inch sweat (solder) fittings. I believe that this means it will solder directly to half inch copper pipe.


Thats what i assumed it meant too, wanted to be sure.
sweat fitting at the pump is probably not the way to go given the life expectancy of a pump.






> I don't see any problem in going from 3/4 at the pump down to half inch. The longer your half inch lines, the greater the pressure drop, and the less flow your pump will put out, but it won't hurt it. Here is the way the flow rate vs pressure drop in the pipes works out:
> 
> http://www.builditsolar.com/References/Pumps/PumpCurves.htm
> So, this 006 puts out 10 gpm with no pipe resistance dropping to 5 gpm with 5 ft of water head pipe resistance.


Well that makes life easier not having to go with a 1/2" outlet pump.
I've just started looking at pumps and its mind boggling all the different pumps for different applications, a new but interesting area for me.
BTW Gary, nice job on your pump page 
Thats a big help in narrowing things down.
Thanks again


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## woodsy (Oct 13, 2008)

Along with Gary's solar system pump page that i posted above, found this 2009 solar pump (AC/DC)catalog with some helpful sizing information in the opening paragraphs pertaining to head and flow rate if anyone else is considering a solar hot water system. Prices in the catalog are somewhat higher than other pump retailers though.


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## woodsy (Oct 13, 2008)

Am considering running my 4X8' collectors in parallel with water running into bottom of one, out the top of the other. Its all 1/2" pipe including manifolds. It seems a simpler way to go,
but will it work OK? 
I am going to do a test, solder the bottoms of my 2nd pipe grid together, stand up and pump water into it @ 2 gpm and see if it exits the top of pipes at the same time.
This should be a rough indicator how 2 coupled together will work.
Any expert opinions welcome...


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## SolarGary (Sep 8, 2005)

Hi Woodsy,

The test is not quite fair in that if you supply water at the (say) lower left corner of the collector, and water exits at the upper right, the total length length of the flow path for every riser is the same. For example, the left riser has no bottom manifold length in its flow path, but a full top manifold. A middle riser has half a bottom manifold and half a top manifold in its flow path. And so on, each riser flow path has one manifold length in it.
But, in your test, the riser next to the supply pipe has no manifold length in its path, and the riser furthest from the supply has a full manifold length in its path.

I think that one thing you could say is that if you get descent flow from each pipe in your test that you are OK, but the opposite may not be true.

Did you see this test?
http://www.builditsolar.com/Experimental/CopperAlumCollector/FlowTest.htm
Based on it, I think (but not sure) that the 8 ft wide would be OK as long as supply and return are on opposite corners.

Another way you could do it with no risk is to supply water to the two lower outside corners, and have a common return from the top center. Its a little more plumbing, but not a lot.

The 2 gpm of for 64 sqft of collector is a bit on the light side to me -- 0.03 gpm per sqft.


If you do the test of flow with only the bottoms of the risers soldered in, I'd really like to hear how it comes out.

Gary


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## woodsy (Oct 13, 2008)

No, I had not seen your test.
Thanks for the input , Interesting test you did there with the temps. of individual risers.Good explanation on how the water flows through the grid.
Should have my test done by later today and will post on it.


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## woodsy (Oct 13, 2008)

My test of the 1/2 " pipe grid showed that with 10 risers, 4.25 " apart, grid width 38.5" x 89.5" high , there was no lag time in any of the risers whatsoever at 2 gpm *or*4 gpm. The water rose equally in all the pipes. The grid was tilted 1/2" as it will be for drainback purposes.
This test was done using a garden hose, measured and timed flow using a gallon jug to set up the gpm flow rate.
The only thing different i can see using this method over a circulator pump is that there was no pressure loss ( I don't think) as head height was attained, the house water supply system runs at about 35 lbs. per sq. in.


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## SolarGary (Sep 8, 2005)

woodsy said:


> My test of the 1/2 " pipe grid showed that with 10 risers, 4.25 " apart, grid width 38.5" x 89.5" high , there was no lag time in any of the risers whatsoever at 2 gpm *or*4 gpm. The water rose equally in all the pipes. The grid was tilted 1/2" as it will be for drainback purposes.
> This test was done using a garden hose, measured and timed flow using a gallon jug to set up the gpm flow rate.
> The only thing different i can see using this method over a circulator pump is that there was no pressure loss ( I don't think) as head height was attained, the house water supply system runs at about 35 lbs. per sq. in.


Hi Woodsy.
Thanks -- good stuff.

Once the flow was going, did you see any difference in the flow rates coming out of each riser? Did the flow from the risers furthest away from the supply seem to be getting any less flow?

Gary


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## woodsy (Oct 13, 2008)

SolarGary said:


> Hi Woodsy.
> Thanks -- good stuff.
> 
> Once the flow was going, did you see any difference in the flow rates coming out of each riser? Did the flow from the risers furthest away from the supply seem to be getting any less flow?
> ...


Hard telling the flow rate from individual tubes without having some means of collecting it.
I'm satisfied that i can couple two 4X8 collectors with minimal loss of fluid flow.
I think i calculated about 56 sq. ft. of collector area with the two I built.


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## woodsy (Oct 13, 2008)

The system is starting to come together.
Built 2 4x8' collector panels and stood one up yesterday to check out 
the location, upper manifold temp check (maxed out at 218 deg.)and tilt angle, 60 degrees it is. Used the fin forming technique that SolarGary suggested except mine are inverted leaving the copper piping exposed to the sun. Had to add some extra bend in the fin so they would clamp the pipe. The whole absorber plate is sitting on 4 horizontal aluminum angle strips about 1" off the foil face insulation.
Plans have changed some from the initial scheme.
Initially thought the panels would be roof mounted but for ease of installation, maintenance, pumping etc. they will now be mounted on the lower south wall and still have full sun.
Found this water tank sitting in the woods on an old farm dump.Got a chain and binder around it and twitched it out with the Deere. Great drainback/heat exchanger tank with no temp restrictions(well maybe some depending on the piping used). Am planning on installing a tempering valve before the electric water heater(per mfgs instructions). 
The tank is a beauty, insulated , rugged , holds about 150 gals.,no leaks just need to make a cover and cut the overflow pipe down closer to the bottom. The pump should hook up easily at the drain pipe with a little adapting, galvanized to copper.
Now, time to do some house plumbing :sing:


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## wendle (Feb 22, 2006)

Nice panels !!! Did you figure out total cost to build?


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## woodsy (Oct 13, 2008)

Thanks, 
The panels were about $200.00 each to build, throw some running around for materials gas money and small misc. stuff on top of that.


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## wendle (Feb 22, 2006)

It looks like all new materials, and they will pay for themselves pretty quickly. I've been staying away from installing on the roof too, mostly because I don't want holes in the roof. The other reason is because if there are any issues, it's so much nicer to work on them at ground level. It turns out there have been some issues to work out, like tightening a few hoses for leaks, rerouting which way the water goes, and cleaning snow off so they will heat up more quickly. I had some issues with getting air out of the lines as well. It all worked out and now I am able to enjoy solar heated water.


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## woodsy (Oct 13, 2008)

> The tank is a beauty


Well, i may have spoken too soon on that.
Found the right coupling and plug to adapt to the threaded drain pipe on the tank. Wanted to seal the drain pipe to see if it leaked.
And ....... drum roll please.......it did.
Water had sat in the overflow/drainpipe and froze cracking the elbow at bottom of tank. Doesn't look to be replaceabale.
If its too good to be true it probably is....


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## wendle (Feb 22, 2006)

Maybe you could ask a welder if it can be fixed or plugged and replaced?
It seems like a nice tank to let go to waste.


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## woodsy (Oct 13, 2008)

wendle said:


> Maybe you could ask a welder if it can be fixed or plugged and replaced?
> It seems like a nice tank to let go to waste.


Along with the leaking drain pipe, i also discovered some serious rotten wood 
framing inside the tank walls/floor when i opened up the bottom exterior panel.
If i can't use it for a drainback tank will use it to store rainwater from the roof for watering the garden.
What do you have for a solar hot water system wendle?


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## wendle (Feb 22, 2006)

I found 6 2X7 solar pool heaters(the ones with copper tubing) on ebay. These are set up in a closed unit system with two water heater tanks. These are heated with 3 side arm heat exchangers, so I don't need any extra pumps, but go on convection. I use a 007 taco pump to circulate the water through the panels, . I don't have any sort of timer or sensors set up but have to turn the pump on manually . My tanks are plumbed to the household water , one is 80 gallon and the other is 40 gallon. The system is also hooked up with an outdoor boiler for winter, or many cloudy cold days. I have some radiant floor heating plumbed in so far, but came across some used baseboard heaters and plan on adding those this winter. 
My plans are to add some more air heaters to the south side of the house and run a few water lines through that to get more hot water in the colder months. 
Yesterday was junk day, I found one more baseboard heater, and a hot tub, which will be added to the system as well. I have been using pv panels with battery storage to power the taco pump on the system. It's cool because when I take a shower I know the water is heated with renewable energy, and most of my system is put together with used(recycled) parts.


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## woodsy (Oct 13, 2008)

Nice setup wendle, thanks for sharing that.

Speaking of recycling, my drainback tank is getting an overhaul, stripped the outer walls and bottom off it, and will rebuild the wood frame and re-insulate . It will be almost as good as new when i get done with it. Its also much easier and lighter to move around stripped down to the inner walls..
The brass elbow that cracked can be brazed for a few bucks.
Good thing that elbow cracked after all seeing the rotten mess that was inside the walls!
My wife wasn't quite as excited about it as i was when i hauled it up to the house with the tractor, LOL. Now i know why.


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## woodsy (Oct 13, 2008)

> The brass elbow that cracked can be brazed for a few bucks.


Turned out to be a bronze elbow but found a guy with a TIG welder and got it fixed for 
$15.00. Back in action framing up the new tank base and shell. 
Buying pump, PEX tubing and more this week.
Looking forward to circulating some water soon....
Speaking of PEX tubing, I don't need the oxygen barrier tubing do I ? 
Another question., Is the head height the height from top of upper manifold to the pump or the point from which water is being drawn.?( near bottom of tank) If I mount the pump just below the tank water line as opposed to the bottom of tank will i be reducing head height?


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## SolarGary (Sep 8, 2005)

woodsy said:


> Turned out to be a bronze elbow but found a guy with a TIG welder and got it fixed for
> $15.00. Back in action framing up the new tank base and shell.
> Buying pump, PEX tubing and more this week.
> Looking forward to circulating some water soon....
> ...


Hi,
If the PEX is the for the pipe coil heat exchanger, you don't need the oxygen barrier. The oxygen barrier is (I believe) intended for closed systems with iron components (like pumps) -- the oxygen barrier keeps air from getting into the system and rusting the pump.

The start up head requirement is the vertical distance from the top surface of the water in the storage tank to the top manifold of the collector. Putting the pump closer to the surface won't make any difference. 

Sounds like you are getting close!

Gary


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## woodsy (Oct 13, 2008)

Thanks Gary
I believe thats called static head which opens up more possibilities for pumps than
i had hoped for. 
Looking at about a 7'-8' head, great news!


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## woodsy (Oct 13, 2008)

I have found determining pump head to be a bit confusing .
Found this link which has helped clear things up for me and thought 
i would share it with others who may have found it confusing.
It seems that total head and static head are the same and this is what the 
pump mfgs use when specifying head criteria.


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## wendle (Feb 22, 2006)

Hey thanks for the link.


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## woodsy (Oct 13, 2008)

wendle said:


> Yesterday was junk day, I found one more baseboard heater, and a hot tub, which will be added to the system as well. I have been using pv panels with battery storage to power the taco pump on the system. It's cool because when I take a shower I know the water is heated with renewable energy, and most of my system is put together with used(recycled) parts.


I was thinking that a hot tub would make a good heat storage vault.
What do you have for PV panel(s)/batteries to run the Taco 007.?
Looks like my pump is going to be the Taco 006.


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## woodsy (Oct 13, 2008)

Stripped down version of salvaged tank

Anyone foresee any issues i might have with this 18 gauge galvanized tank in using it with hot water to 150 deg. maybe ?????.

Haves since rebuilt the base and frame and have it on a 4x4 stand in the basement, almost ready for plumbing.

Its 3'x3'x2.5' deep and with 300' coil of tubing should hold about 125 gallons.


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## ericjeeper (Feb 25, 2006)

Your system is really coming along nicely..
If you have any worries about the tank you can always add a waterproof liner of some sort. Either in a liquid form such as fiberglass resin,or some type of marine paint possibly.


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## wendle (Feb 22, 2006)

This system is 84 square feet of solar water panels(used from a pool system)








The taco pump is run with 450 watts of solar panels and 4 six volt batteries combined to make a 12 volt system. I don't know that the solar panels are the "right" amount, and have also been able to run other things at the same time, with no troubles. 
Below is a picture of the plumbing. This is my first plumbing job, so it isn't the neatest, or the best. I have already found things I need to tweak to make it better. 
The water could go slower through the panels in the spring and fall to gain higher temperatures. I also plan on adding more plumbing through a few of my solar air heaters , besides adding a holding tank to the closed loop system. 

The panels could be insulated and will be. 

The second water heater isn't set up to run with the wood boiler system, just the solar water heater, and even though it isn't needed, it would be more hot water storage. 

Two of the heat exchangers are cheaply made(thus the bent piping) I had some difficulty with some messed up threads from the manufacturer, so ended up with some leakage, and the thin copper would bend easily. 
The tank on the left has two heat exchangers each about 12 inches. This was my first one to install. The tank on the right(40gal) has one heat exchanger about 18 inches long. 
There are two taco pumps, one for the boiler and one for the solar. I set them up sort of two separate systems, but will change that, so either pump can be used. 
The lines going every which way on the left tank are for the radiant floor heating, connected to two manifolds. 
Each tank has it's own pr valve, plus one on the outdoor boiler, and one in line near the gauges. 

It all looks somewhat disorganized, but works well. 











I was thinking the hot tub can be some water storage, but only up to a certain temperature if I am going to use it myself. I might have to use a heat exchanger on that as well, or just plumb it into the regular household water system.


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## woodsy (Oct 13, 2008)

My pump and PEX tubing coil should be on the doorstep tomorrow. The PEX tubing will be used for heat exchanger incorporated into the house potable water supply.
I am new to PEX tubing but can run copper like theres no tomorrow.
What would be the best connection device to go from 1" PEX pipe to 3/4" copper?????
I've looked into the sharkbite and watts brass reducers and they are pricey but look like a quick fix. Any other just as good alternatives cheaper?
house water system runs about 45psi.
Thanks.


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## woodsy (Oct 13, 2008)

The new DIY custom designed/built drainback solar hot water system is up and ready for sunshine. Heres a







[/IMG] of the tank and 300' x 1" coil heat exchanger PEX tubing. I picked the pretty blue color for contrast.
The Taco 006 is circulating the water at about 3 gpm.
More later....


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## wendle (Feb 22, 2006)

Wow!!Nice set up! You have been working on it. Please let us know what sort of heat you are getting out of it.


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## woodsy (Oct 13, 2008)

1st day of partial sunshine brought the 125 gallons of water in the drainback tank up 25 degrees, starting out at a cold 51 deg and rising to 76 deg. Ran the pump 2-3 hours.
It will be a manual operation for now till some money for the controller comes in.
I want to tell you all how grateful I am to SolarGary and his Build it Solar Website. All of the details he has provided on how to and what to use has helped make this project come together nicely.
There were a couple moments of despair over the course of about 4 weeks it took to assemble everything, once when i opened the valve to the new house plumbing and had 3 leaks to fix, again when i turned the circulator pump on and had 2 more leaks to fix. Overall not too bad considering the magnitude of the project being built from scratch and 150 soldered connections later.
The Panels don't look too bad mounted on side of the house and seem to compliment my passive solar design/build. You can't see it through the glass but the drainback tank sits just below the window bottom left of picture. We use only wood to heat this house, about 4 cord per year max.


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## woodsy (Oct 13, 2008)

Two partly sunny days has brought the tank water to 90 deg, full sun today and hoping for 120 deg. by days end.
The electric water heater was piped with 2 valves, i can direct water from 
the heat exchanger through it or completely bypass it.
Once we get to the 120 deg mark i expect we will be mostly bypassing the electric water heater and keep it power off .
The circulator pump draws 60 watts , a WHOLE LOT less that the electric water heater.


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## SolarGary (Sep 8, 2005)

Hi,
Looking good.

Great job on the house as well -- I notice that most of the windows are well shaded by the roof overhangs.

Gary


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## woodsy (Oct 13, 2008)

Thanks, the overhangs are adequate and the roof windows get covered with upside down lightweight wooden boxes i made, usually go on in June and come off in Sept sometime.
So when the tank water hit 100 today about 1pm, i topped it off with about 6" of 50 deg water.(20-25 gals.? )
Got it back up to 100 by days end so maybe 120 tomorrow? pretty good considering it was 70 deg starting out. 
The pump runs very well with but gets pretty hot when running constantly.
Overall everything is holding up well, all those soldered connections etc.
I am really excited about having this running so well and cutting the electric bill in 1/2 hopefully!
Gary, once i get caught up on other put aside tasks, i'll put together a detailed account for you to consider for BIS.

woodsy


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## woodsy (Oct 13, 2008)

We have had a pretty good start-up week with most days being at least partly sunny. Have probably run the circulator pump about 16 hrs. in 4 days.
Shut the power off to the electric water heater early yesterday morning and closed the ball valve to it and we are now getting our hot water direct from the heat exchanger piping in the drainback tank, bypassing the electric water heater completely.
Its been averaging 100-110 degrees in the tank as of yesterday and we have been drawing 50 deg. water through it all week.
Expecting the temp to increase as days go by and we get accustomed to using the hot water more conservatively, and adjusting our usage to when the sun shines down upon us .
There are 3 members in this household using it.
I think this system is going to work great!


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## woodsy (Oct 13, 2008)

System performance seems to be good, don't really know what to expect being a greenhorn.
Had a couple days of no solar gain and heat exchange tank temp dropped to 75 deg. Of course we were drawing cold water through it and running the electric water heater some, the high schooler needs a long wake-up shower in the morn.
Yesterday was a prime solar gain day, deep blue sky and no clouds at all, ran the circulator pump 8.5 hrs. and brought the 130+- gals. of water in the heat exchange tank to 105 deg.
That seems to be pretty good considering the # of gallons we are heating. Up 30 degrees in a day.
Not really sure yet.
Saving money on electricty though, payback has already started!
Don't know if circulating 3 gals. per minute is too much for 52-53 sq. ft. of absorber area?
If i reduce the water level in the tank some i can reduce the flow rate some.


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## frank (Dec 16, 2008)

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## frank (Dec 16, 2008)




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## frank (Dec 16, 2008)




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## frank (Dec 16, 2008)

Woodsy Congrats on discovering Garys' system!

Thanks again Gary!


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## frank (Dec 16, 2008)

Mine is serpentine 1/2" copper, home depot submersible pond pump on a timer, and a second serpentine collector on the cover.No fins on the cover collector, just copper sprayed black under a polycarbonite cover with pvc sides/silicone for now. Temp star elec 15 in the house(which is shut off) even fills the jacuzzi tub outside! Unreal how well this thing works! Elect from 140, to 80, then 60$


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## woodsy (Oct 13, 2008)

frank said:


> Woodsy Congrats on discovering Garys' system!
> 
> Thanks again Gary!


Yeah, great find, ask and ye shall receive kind of thing. I am liking it.



frank said:


> Mine is serpentine 1/2" copper, home depot submersible pond pump on a timer, and a second serpentine collector on the cover.No fins on the cover collector, just copper sprayed black under a polycarbonite cover with pvc sides/silicone for now. Temp star elec 15 in the house(which is shut off) even fills the jacuzzi tub outside! Unreal how well this thing works! Elect from 140, to 80, then 60$


I'm hoping to see that kind of reduction in my elec. bill too.
Looks like you've got something good going too.
Something i didn't realize about the PEX tubing we are using is when you order 1" tubing you get 3/4" I.D. tubing, not 1" I.D.
However, this seems to exchange the heat very well with the thick walled tubing.
.


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## SolarGary (Sep 8, 2005)

woodsy said:


> System performance seems to be good, don't really know what to expect being a greenhorn.
> Had a couple days of no solar gain and heat exchange tank temp dropped to 75 deg. Of course we were drawing cold water through it and running the electric water heater some, the high schooler needs a long wake-up shower in the morn.
> Yesterday was a prime solar gain day, deep blue sky and no clouds at all, ran the circulator pump 8.5 hrs. and brought the 130+- gals. of water in the heat exchange tank to 105 deg.
> That seems to be pretty good considering the # of gallons we are heating. Up 30 degrees in a day.
> ...



Hi Woodsy,
System is looking good.

It does take the tank a while to react when you get a good day or two of sun because the tank is pretty large, but that allows you to store more heat for cloudy days.

The 3 gpm for 52 sf is fine. Its 0.06 gpm/sf. The recommended range from Heliodyne is 0.025 up to 0.07 gpm per sf -- so you are just a bit above the middle of that range.
If you ever wanted to add more collector, you could nearly double the collector area, and still be in the OK flow rate range on that pump.

Gary


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## woodsy (Oct 13, 2008)

Thanks for the input Gary, 
You have been a really big help with all the technical data.
We are cooking today with full sun and 88 deg.
hoping to see some 110-120 deg storage tank temps today.
Pretty exciting after all that work.


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## woodsy (Oct 13, 2008)

Getting ready to make the last purchase on the hot water system 
But, which controller ?
Looking at this one(AIBC) but not sure if the surge protection is adequate 
The Steca 0301 U looks good for more money($46.00 more in total)
Both get good reviews, any personal experiences with either model out there?


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## SolarGary (Sep 8, 2005)

woodsy said:


> Getting ready to make the last purchase on the hot water system
> But, which controller ?
> Looking at this one(AIBC) but not sure if the surge protection is adequate
> The Steca 0301 U looks good for more money($46.00 more in total)
> Both get good reviews, any personal experiences with either model out there?



Hi,
I use the Steca one and like it. Its nice compared to the Goldline style controllers in that it has some readouts so you can see temps at a glance.

Had not heard of the AIBC one -- it may be new.
It appears to have more features and more flexibility -- it can apparently control a variety of pumps and valves. Also comes with 4 temperature sensors (I guess) -- the Steca comes with 2, and will take a 3rd as an option.
It would be nice if you could get some reading on its reliability, since this is what you really want from a differential controller more than anything else.

If you get the AIBC, would like to hear how it works out.

Gary


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## woodsy (Oct 13, 2008)

Thanks for your input Gary, I seem to recall you said that your Steca controller failed once? 
If so what was the problem?
I found this review of 4 different make controllers incl. the AIBC model, about all i could find so passing it along to anyone else that might be interested, has a brief conclusion @ bottom of page.
Looking forward to hooking this piece of equipment up, today i've made about 8 trips to basement to turn the pump on and off as the sun appears and disappears for spells..


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## SolarGary (Sep 8, 2005)

Hi,
I did have a failure of the Steca. It would run the pump all the time, no mater what the collector or tank temp -- kind of like the pump relay or scr was stuck on. They replaced it under waurantee, and have had no trouble with the new one. I guess I am willing to chaulk it up to one bad unit.

I read through the manual on the AIBC one. This is just me, but I would not buy it until I heard from some satisfied users that it works reliably. It has more features than you can imagine, and the manual feels like one of those translated badly from some other language -- this all just makes me uncomfortable -- the combination of something that has a lot of complex features and no track record. Again, this is just me.

If you don't need the readouts, I've had the Goldline working on the solar heating system now for 3 seasons -- its out where its exposed to cold temps, and has never missed a beat. This also their reputation -- quite reliable. But, I do like the readout on the Steca -- it tells you at a glance how things are going.

Gary


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## greif (May 31, 2009)

"For me, the idea for the small drain/vent hole came from NZ Mike on the Solar Thermal forum"

gary, were is this solar thermal froum?

thanks
greif


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## woodsy (Oct 13, 2008)

SolarGary said:


> Hi,
> 
> 
> I read through the manual on the AIBC one. This is just me, but I would not buy it until I heard from some satisfied users that it works reliably. It has more features than you can imagine, and the manual feels like one of those translated badly from some other language -- this all just makes me uncomfortable -- the combination of something that has a lot of complex features and no track record. Again, this is just me.
> ...


And, i think the AIBC unit can only be bought from across the pond as we say around here( U.K.), therefore, any problems means big hassle w/shipping and time issues.
I do like the Steca model, but can only find a couple dealers back east
One dealer is 30.00 more than the other, the other won't take credit card orders over the phone and is acting like a real hassle to deal with. Guy is credit card theft paranoid.
Somehow online CC transactions are more secure than land line?
I have found that dealing with some of these outfits is a PIA w/ personal information , needing to register for company on line accounts etc. etc. in order to purchase anything from them.
Anyone know where I can get a Steca TR0301U for under 160.00?
I've already looked into East Coast Solar and Sun Earth Inc
Thanks
BTW, the new system is working great, brought tank(130 gals.) temp up 35 degrees yesterday, 
i think one more collector would make this system rock !


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## SolarGary (Sep 8, 2005)

woodsy said:


> And, i think the AIBC unit can only be bought from across the pond as we say around here( U.K.), therefore, any problems means big hassle w/shipping and time issues.
> I do like the Steca model, but can only find a couple dealers back east
> One dealer is 30.00 more than the other, the other won't take credit card orders over the phone and is acting like a real hassle to deal with. Guy is credit card theft paranoid.
> Somehow online CC transactions are more secure than land line?
> ...


Hi,
I got my Steca from SolarTrope (I hope thats the right spelling).
You might give them a try.
On a scale of 0 to 10, I would give them a 5 on customer service, but when my first unit failed they did eventually come through with a replacement.

Gary


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## SolarGary (Sep 8, 2005)

greif said:


> "For me, the idea for the small drain/vent hole came from NZ Mike on the Solar Thermal forum"
> 
> gary, were is this solar thermal froum?
> 
> ...


Hi Gary,
The group is alt.solar.thermal -- its a usenet group. Not to active, but some good people on it. If you don't have a usenet provider, Google has a setup that allows you to post to usenet groups. Just Google for Google Groups 

Gary


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## woodsy (Oct 13, 2008)

The system is now complete and fully automatic with the installation of the Steca controller this week.
The electric bill shows a $ 30.00 reduction in the 1st complete month of use (29 days) and can count on two hands the # of full sun days we've had last month, it is rainy season here.
We had about 10 days of solar direct hot water over the last month.(bypassing the electric water heater completely). 
To put it into perspective, we used 446 KWH last month, big improvement, down from 6-700 KWH per month. 
Woohooo!!!!


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## SolarGary (Sep 8, 2005)

woodsy said:


> The system is now complete and fully automatic with the installation of the Steca controller this week.
> The electric bill shows a $ 30.00 reduction in the 1st complete month of use (29 days) and can count on two hands the # of full sun days we've had last month, it is rainy season here.
> We had about 10 days of solar direct hot water over the last month.(bypassing the electric water heater completely).
> To put it into perspective, we used 446 KWH last month, big improvement, down from 6-700 KWH per month.
> Woohooo!!!!


Sounds good!

Got any more pictures?

Gary


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## artificer (Feb 26, 2007)

woodsy said:


> ...
> Anyone know where I can get a Steca TR0301U for under 160.00?
> I've already looked into East Coast Solar and Sun Earth Inc
> Thanks


$139.95 with $13.45 shipping (9 days from 24Jun09)
http://cgi.ebay.com/STECA-TR0301U-S...-CONTROL-_W0QQitemZ170318264111QQcmdZViewItem

$159.95 
http://www.eastcoastsolarsystems.com/comersus/store/comersus_viewItem.asp?idProduct=39


I've seen the ebay add on dozens of sites. Everything else is $159.95 or $175.

Michael


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## woodsy (Oct 13, 2008)

SolarGary said:


> Sounds good!
> 
> Got any more pictures?
> 
> Gary


I do have a couple pics of the completed system in the basement, i need to upload them( dial-up, arrgh!).
I'll be putting together the construction details w/photos sometime soon for BIS
but still can't get outlook express to work, a computer glitch on my end. 
We'll get it to you somehow Gary.


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## woodsy (Oct 13, 2008)

artificer said:


> $139.95 with $13.45 shipping (9 days from 24Jun09)
> http://cgi.ebay.com/STECA-TR0301U-S...-CONTROL-_W0QQitemZ170318264111QQcmdZViewItem
> 
> $159.95
> ...


My Steca came all the way from New Mexico, took about 12 days on the slow train, a couple days longer than expected.
Hard to believe these controllers can't be distributed from somewhere on the East coast, the company i ordered it from was on the East Coast, but was not East Coast Solar.


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## summerdaze (Jun 11, 2009)

Kevingr said:


> Check out Gary's website. www.builditsolar.com Tons of info there.


Decided to check out the site. Under new content was an article "who knew there were so many ways to use old tires?" There's a guy, Cory Christofferson, that made 8 miles of fencing, numerous corrals for his animals, shelters, windbreaks, etc all from used tires. He had a large garden that he grew inside of tires too. His creative ideas and hard work are inspiring! I love to see the awesome things that can be made from "junk" and turned into something useful again.

Unfortunately, the state stepped in, took him to court, and made his life miserable. They drained him of his money, threatened to take away his farm etc..He appealed but lost.

This just shouldn't happen to good, hard working, not to mention creative and thrift folks by state government. It's probably only the tip of the iceberg though, now that government's putting it's nose more and more into our business. 

But anyway, The pictures are worth seeing, and I'm sure there are other states that would welcome people with good recycling ideas. Here's a tip North Dakota...burying in a landfill and incineration is NOT recycling!! 

Guess this has nothing to do with the topic at hand, but thought it was worth passing along since it was generated from a recommended website here.


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## greif (May 31, 2009)

why, where they worried about tires fire or something?


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## summerdaze (Jun 11, 2009)

They mentioned that but it sounded like there wasn't any prairie grass around it to burn and catch the fence on fire. The fencing was all in a straight line, so if by chance it did catch, he would just need to knock a section down with a back-hoe which he had on the property. They also said that they'd fill up with water and attract mosquitoes, although the guy and his neighbor did an independent test and found no problems. Not one of the "experts" that testified for the state against him had ever been out to his place or run any tests of their own. It was all a bunch of "what if?" it sounded like. Now they're demanding that he take it all down and dispose of the tires in the excepted method-landfill. I don't get it. It's interesting too, that the guy always requested and received the proper permits etc, (which you can view online) and had the ok from the state to go ahead with his project. At some point the state people changed their minds and started making his life a living ugh,.. nightmare. Sad and discouraging story. Government squashes the little guy again.


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## woodsy (Oct 13, 2008)

For those of you who have followed this thread and are interested in more complete details including pictures of the project, Solar Gary has taken the time to work with me on a draft of the project for his website and it can now be seen on BuildItSolar.com.

Thank you Gary for all the help and information you provide at BuildItSolar. !!
A great resource for DIYers !!


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## frank (Dec 16, 2008)

Hi Gary & Woodsy, 
I just received my Stecca 0301. It came with two sensors (round pin crimped on silicone cable) Is the sensor waterproof, or should I put the sensor under the epdm in the side/bottom of the tank liner? Or can I just immerse the sensor in the tank water? I don't want to partially disassemble the tank to get "under" the liner if I don't have to. Thanks for any input...

By the way, I'm very impressed with this design. It works well even without the Stecca!

Thanks once more Gary!
Frank


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## frank (Dec 16, 2008)

Woodsy, I read your link above...about the woodstove...I installed 3/8 copper in the exhaust on my dogwood stove 6". It works very well and without it I would have had to turn on my electric heater in the house...lol. My tank (and stove) are outsine. I use a quick disconnect shark byte to switch the pump output to the stove and the stove has it's own return line. this setup is working really well.
Frank


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## woodsy (Oct 13, 2008)

frank said:


> Hi Gary & Woodsy,
> I just received my Stecca 0301. It came with two sensors (round pin crimped on silicone cable) Is the sensor waterproof, or should I put the sensor under the epdm in the side/bottom of the tank liner? Or can I just immerse the sensor in the tank water? I don't want to partially disassemble the tank to get "under" the liner if I don't have to. Thanks for any input...
> 
> By the way, I'm very impressed with this design. It works well even without the Stecca!
> ...


I did not read anywhere that the sensor and wire could not be submerged in water, and my tank sensor is in the tank water. Seems to be fine so far.



frank said:


> Woodsy, I read your link above...about the woodstove...I installed 3/8 copper in the exhaust on my dogwood stove 6". It works very well and without it I would have had to turn on my electric heater in the house...lol. My tank (and stove) are outsine. I use a quick disconnect shark byte to switch the pump output to the stove and the stove has it's own return line. this setup is working really well.
> Frank


Thats interesting, been trying to figure out how to use the circulator pump
to feed the wood stove loop.
I 'm thinking if i add a T downstream of pump with a shutoff valve for the collector side of the system and another shutoff valve for the wood stove loop it would work with either loop or both loops running, but should have all the details worked out by winter.
A 50' 1/2" copper coil laying on top of the box type wood heater, open loop.
Should have plenty of hot water this winter...


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## SolarGary (Sep 8, 2005)

frank said:


> Hi Gary & Woodsy,
> I just received my Stecca 0301. It came with two sensors (round pin crimped on silicone cable) Is the sensor waterproof, or should I put the sensor under the epdm in the side/bottom of the tank liner? Or can I just immerse the sensor in the tank water? I don't want to partially disassemble the tank to get "under" the liner if I don't have to. Thanks for any input...
> 
> By the way, I'm very impressed with this design. It works well even without the Stecca!
> ...



Hi Frank,
I've also been running with the sensor submerged in the tank -- no problems.

Gary


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## frank (Dec 16, 2008)

Thanks guys, I appreciate the input... Woodsy, I ran 20 feet of 3/8 in a coil inside the 6 inch exhaust and it gets really hot! 'Haven't measured the temp but I think you might boil with 50 feet of copper...depending on where the copper is located in/on your stove. The selector valve sounds good to me. Mine is real simple , I just grab the shark byte and plug into the stove. On cloudy days ( 2or3 in a row) it works awesome. Thanks again!
FRank


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## Jennifer L. (May 10, 2002)

Hey, this is probably a dumb question, but when you build a 4 x 8 (for example) collector for a system like this, does it make any difference as far as ability to drain back if the collector is set up on its long side rather than its short side? It seems that it would be better to put it tall side up, but is that more of an illusion than anything? It gets pretty cold here in the wintertime and the logical spot I have for a collector (don't really want to go the roof route) would be better long side down.

And while I'm at it, is there any formula for figuring out how many risers you need in the collector? Or is it more or less common sense on the amount of soldering and fussing you want to do with the aluminum backing? Is the only benefit to more risers faster heating to the tank? Which may not be much of an advantage when push comes to shove.

Thanks. This has been a fascinationg thread to read and Gary's site is great, too.

Jennifer


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## SolarGary (Sep 8, 2005)

Hi,
All good questions.

You can orient the collector vertical or horizontal as long as the riser run up and down. For good drain back, the whole assembly of manifolds and risers needs to be "clocked" a little bit so that the lower manifold slopes toward the side where the supply pipe comes in. 
One of the advantages of building it yourself is that you can make the collector just about any shape you want.

You want the riser spacing to be narrow enough so that for the fin material you use, the fin is able to efficiently transfer the heat into the riser tubes. This depends on the fin material and the fin thickness. There is a fin efficiency equation that can be used to calculate it, but some combination that work pretty well:

My homemade collector uses 0.018 thick aluminum fins with a riser spacing of 6 inches -- this gives about 95% fin efficiency. This 0.018 alum is sold as aluminum soffit material -- its called Rollex System 3 soffit.

A lot of commercial collectors use copper fins that are about 0.008 thick with about 4.5 inch riser spacing -- if I am recalling right, they also come out about 95% fin efficiency.

Gary


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## woodsy (Oct 13, 2008)

I could not find the Rollex Soffit material anywhere in this area .

Therefore, followed the pipe spacing practices of the manufactured collectors thinking that more pipes = more heating surface.


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## woodsy (Oct 13, 2008)

Solar hot water system update/savings:
The 2nd full month of operation during a very rainy month showed another 200 KWH+ reduction in electric bill for savings of $30.00. Backup is electric water heater, mostly off but used it when needed.
If we can get some normal weather in here, savings could jump up to $40.00 or more per month!
I highly recommend anyone wanting to save some money on utilities to look into solar hot water. 
We pay about .15 cents per KWH in these parts so it really adds up.
Estimating payback for this homebuilt system within 2-3 years.


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## woodsy (Oct 13, 2008)

Update, for anyone interested.
The DIY system has been working better than could have imagined. 

The unusually wet summer finally broke some 3-4 weeks ago and the heat exchange tank with 140 gals of water has been seeing 130- 140 degree temps almost daily, with regular use of hot water for showers, dishes, laundry etc. 
The controller has shut the pump down on a couple afternoons recently.

Last months electric bill showed another $30.00 in savings and the electric water heater has been shut off at the breaker for about a solid month.

The 60 degree tilt on the collectors is starting to really crank the hot water out as the sun lowers on the horizon.

Its fun getting all of our hot water from the sun!


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## byexample (Aug 28, 2009)

If you are in a climate that is subject to deep freezes I strongly recommend against the panel collectors unless you also include an anti-freezing drain-back system or are running a system that uses an anti-freeze operating liquid with a heat exchanger.

Our first solar hot water collector was a basic flat panel collector that worked very well. But we had a freak unexpected freeze one night that totally wrecked the collector. And it didn't even get that cold... something in the low 20s as I recall.

Our second collector is a batch heater that we've been using for 4 years now. It's survived temperatures below zero many times now over the years. It's essentially a stripped down, painted tank in an insulated box with a patio door on top... very inexpensive to build since most of the materials were salvaged. Here's a link to an article about how it was constructed:

http://www.byexample.com/projects/current/batch_collector/index.html

We've seen condensation issues on both of our collectors here in AZ. Moisture will build up on the glazing of the collector and then it actually blocks some of the thermal energy and slows down the morning warm-up time of solar hot water. Definitely recommend some sort of vent and drain on all solar hot water collectors.

A few more very important pieces of advice for do-it-yourself solar hot water systems:

1). Expect leaks... and make sure you have drains installed!!! (learned this the hard way... had to bail the box out with a bucket once)

2). Have a plan for draining the system. Water weights a lot... a 40 gallon tank has 320 lbs of water in it. Sooner or later you will need to do some maintenance, more the collector, etc.. You got to be able to drain the system... especially if you are building a batch collector.

3). Try not to use a tank that's been sitting outside unprotected. Even if there isn't freeze damage there likely is rust damage and the tanks will rot out on you faster. Most tanks are steel... and steel rusts in the presence of oxygen and water.

4). Make sure you orient your tank(s) so that you can get ALL the air out of them. Again, steel rusts in the presence of oxygen and water. Get the air out and you reduce the rust / rot factor.

5). Make sure you have a Temperature Pressure Relief (TPR) Valve installed. As water heats up it expands, which increases pressure in the system. The TPR will let out a little water if need be to bring the pressure down to a safe level.

6). Saved this for last because I think it's the most important... solar hot water can get very, very hot. Dangerously hot. We've seen temperatures in our batch collector above 150F!!! That's hot enough to scald in seconds. Water this hot is dangerous for the very young and very old. I strongly recommend that any and all solar hot water systems include the use of a tempering valve. A tempering valve mixes in a little cold water into your hot water line to keep the temperature regulated to a more reasonable level. Something like 120F. This makes the water safe for the little ones and it also makes your hot water last longer... a lot longer.

Best of luck with your solar hot water heater. Solar hot water is fabulous and can save you lots of money if you build your own system.

Be well,

Patrick Harris
http://ByExample.com


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## woodsy (Oct 13, 2008)

DIY, part two, open loop 20' copper coil on top of woodstove (under vented grate) .

This loop will flow through the existing open loop solar hot water heat exchange tank(150 gallons).
I plan to tee off the existing line out of tank above the pump and install shut off valves to the solar side as well as the wood stove loop so they may be used independently or together.
Cost for this extra water heating source about $100.00 for materials.
The circulator pump will be switched on and off manually.
Anyone see a problem with this add on ? Any dangers or other problems that i am not realizing ? The current system is good to 180* but only planning to go 140-150*.


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## SolarGary (Sep 8, 2005)

woodsy said:


> DIY, part two, open loop 20' copper coil on top of woodstove (under vented grate) .
> 
> This loop will flow through the existing open loop solar hot water heat exchange tank(150 gallons).
> I plan to tee off the existing line out of tank above the pump and install shut off valves to the solar side as well as the wood stove loop so they may be used independently or together.
> ...



Hi Woodsy,
One thing to be careful about is that the loop through the wood stove either 1) cannot be isolated with valves, or 2) has a pressure/temperature relief valve in it. If you have a closed loop (valved off on both ends) that goes through the stove, you can get a steam explosion, and they can be very very damaging.
http://www.woodheat.org/dhw/dhw.htm

If you do add a pressure/temperature relief valve, make sure that it can't be isolated from the part of the loop that goes through the stove with the valves you are using to shut each loop off.

Gary


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## byexample (Aug 28, 2009)

SolarGary said:


> Hi Woodsy,
> One thing to be careful about is that the loop through the wood stove either 1) cannot be isolated with valves, or 2) has a pressure/temperature relief valve in it. If you have a closed loop (valved off on both ends) that goes through the stove, you can get a steam explosion, and they can be very very damaging.
> http://www.woodheat.org/dhw/dhw.htm
> 
> ...


I was doing research on steam engines a few years back and I got to talk to an old-timer that used to work with steam and steam engines in the day. At one point he warned me that when working with boilers that *"there's a stick of dynamite in every gallon of water"*.

And he was serious enough about it that it really stuck with me.

Any time you are heating water it's a really good idea to have a TPR somewhere in the system or otherwise you risk a catastrophic leak and perhaps even serious injury. Steam is a powerful force.


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## woodsy (Oct 13, 2008)

SolarGary said:


> Hi Woodsy,
> One thing to be careful about is that the loop through the wood stove either 1) cannot be isolated with valves, or 2) has a pressure/temperature relief valve in it. If you have a closed loop (valved off on both ends) that goes through the stove, you can get a steam explosion, and they can be very very damaging.
> http://www.woodheat.org/dhw/dhw.htm
> 
> ...


Hi Gary, 
Thanks, got it.
Ill have an update for Build it Solar when this new loop is up and heating water by wood stove. Got to love the simplicity of open loop water 
systems. :bow:


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## artificer (Feb 26, 2007)

byexample said:


> I was doing research on steam engines a few years back and I got to talk to an old-timer that used to work with steam and steam engines in the day. At one point he warned me that when working with boilers that *"there's a stick of dynamite in every gallon of water"*.
> 
> And he was serious enough about it that it really stuck with me.
> 
> Any time you are heating water it's a really good idea to have a TPR somewhere in the system or otherwise you risk a catastrophic leak and perhaps even serious injury. Steam is a powerful force.


A quick check finds dynamite has about 3200btu/lb. At around 1000btu/lb for steam, a gallon would be 8000btu/gal. It would take around 4 sticks of dynamite to have the same energy as the gallon of water. NOT something to play around with casually.

Michael


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## byexample (Aug 28, 2009)

> A quick check finds dynamite has about 3200btu/lb. At around 1000btu/lb for steam, a gallon would be 8000btu/gal. It would take around 4 sticks of dynamite to have the same energy as the gallon of water. NOT something to play around with casually.


Wow, you mean that old timer was being conversative??


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## woodsy (Oct 13, 2008)

The new woodstove coil loop got tested out some over the last couple days.
It circulates 1 gpm through the 20' X 3/8" I.D coil.
Any pressure from startup steam is released at the drainback/heat exchange tank which is not completely sealed around the tank cover where the now 2 lines drain into it.
Both loops, solar collector and woodstove can run simultaneously but the smaller woodstove loop must be filled first or else it won't circulate at all. , an interesting quirk, possibly due to the smaller dia. coil and increased resistance from it. ?

The woodstove loop alone is not getting the tank temp charged up as much as I expected, maybe a couple degrees an hour at best. There is only about 3 sq.ft. of stovetop to work with but may be room for another 20' coil or replace the current one with a larger inside dia. coil.
And the hotter dead of winter fires may increase the temp charging rate some too.


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## artificer (Feb 26, 2007)

artificer said:


> A quick check finds dynamite has about 3200btu/lb. At around 1000btu/lb for steam, a gallon would be 8000btu/gal. It would take around 4 sticks of dynamite to have the same energy as the gallon of water.





byexample said:


> Wow, you mean that old timer was being conversative??


I've thought about this, and to be accurate, 4 sticks of dynamite would equal 1 gallon of water turned to steam. 1 gallon of water under presure would only have 180btu/lb, 1440btu/gal, or only 3/4 stick of dynamite. Still... makes you think.

Michael


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## woodsy (Oct 13, 2008)

> The woodstove loop alone is not getting the tank temp charged up as much as I expected, maybe a couple degrees an hour at best. There is only about 3 sq.ft. of stovetop to work with but may be room for another 20' coil or replace the current one with a larger inside dia. coil.
> And the hotter dead of winter fires may increase the temp charging rate some too.


This wood stove loop is working out well in keeping the heat exchange tank in the 80- 100 degree range. I was able to increase the efficiency of the coil by working dry sand in around and on top of the coil to serve as a thermal mass, then covered it with metal plate and topped that off with firebrick. Can get 3-5 degrees per hour rise in temp( 150 gals.) depending on how hot the wood stove is. We have not had much solar gain lately with winter weather and short daylight days but thats changing now for the better.
I usually make sure the valve to the solar side is open in the morning but forgot that this AM and the pump had kicked on when i did check it at 10 o'clock. The outside ambient air temp was 0 and the air temp in the collector was 167 degrees! With the heat exchange tank temp already at 98 *, we should get that into the 120*range from just the solar side today under clear skies .


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## krysto (Jan 18, 2010)

Woodsy - I saw your article on Gary's BuildItSolar site. Great stuff. When you described how you made your aluminum fins for the solar collector with the steel rod method, you said "I then pulled the rod out and continued the bend just enough so that it would clamp the pipe securely". Can you describe a bit more how you continued the bend? By hand? Sorry - I cannot visualize it.

Thanks


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## woodsy (Oct 13, 2008)

Yes, I pulled the fin out of the mold , grasped both sides with hands and continued the bend beyond 180 degrees, then bent only the flat sides of the fin back to roughly180 degrees leaving the round part able to clamp the copper pipe. This took a little practice to get it right, not an exact science.
In retrospect, the fins flat sides came out slightly rippled , not perfectly flat due to the extra bending. It might be possible to find another way to do this, maybe clamp some boards to the metal fins and then do the bending instead of the hand method.
Also, a guy makes these on Build it Solar, may be worth looking in to ? http://www.builditsolar.com/Experimental/TomPress/TomPress.htm#Finished


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## krysto (Jan 18, 2010)

When you pound the steel rod into the aluminum, I assume the two sides bend upwards quite a bit, right? Then you have to straighten them back down - regardless of whether you perform the extra manual bend you describe? How is it that the fins get rippled because of the "extra bending"?


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## SolarGary (Sep 8, 2005)

Hi,
I not sure exactly how Woodsy did his, but there are a couple pictures of the fin pounding process on this page:
http://www.builditsolar.com/Experimental/CopperAlumCollector/Construction.htm
About half way down the page.

The way I've been doing it, I use the flat part of the sledge -- this simultaneously pounds the rod into the groove and flattens out the fin so that the sides don't bend up. 

There are also a couple other grooved fin sources listed with the pictures.

In addition, Tom has a new wrinkle on the fin making in his latest project (which is a dandy):
http://www.builditsolar.com/Projects/SpaceHeating/TomLargeCol/TomCol.htm

Gary


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## krysto (Jan 18, 2010)

Gary -
The jig you use for the fins - is the depth of the groove you make with the two wooden pieces 5/8"? If it was 3/4", would that make too deep a depression in the aluminum - or does the fact that you use the sledge on the flat keep it from going too deep? Your photos are great!


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## woodsy (Oct 13, 2008)

> gary : The way I've been doing it, I use the flat part of the sledge -- this simultaneously pounds the rod into the groove and flattens out the fin so that the sides don't bend up.


Thats the procedure i used too.
krysto, I thought 5/8 " deep was enough to get some wrap around on the 1/2" copper piping.
Get your jig set up like Gary has shown and practice on a couple pieces , practice makes almost perfect. I don't think the fact that the fins may not be perfectly flat affects performance any. But I'm not much for perfection anyway, good enough !


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## krysto (Jan 18, 2010)

What I meant was, standard boards are 3/4" thick. So if the jig used boards like that to form the groove, the groove is 3/4" deep. Does that work for copper pipe that is 5/8" OD? I guess that a 5/8" steel rod cannot get driven deeper than 5/8", no matter how deep the groove is, unless you hit the rod with something narrow. The sledge gets "stuck" on the sides of the jig, and so the rod does not get pushed any deeper than 5/8". Just talking it out to understand it.


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## SolarGary (Sep 8, 2005)

krysto said:


> What I meant was, standard boards are 3/4" thick. So if the jig used boards like that to form the groove, the groove is 3/4" deep. Does that work for copper pipe that is 5/8" OD? I guess that a 5/8" steel rod cannot get driven deeper than 5/8", no matter how deep the groove is, unless you hit the rod with something narrow. The sledge gets "stuck" on the sides of the jig, and so the rod does not get pushed any deeper than 5/8". Just talking it out to understand it.


Hi,
I used 5/8ths plywood, so in my case, the sledge pushes the metal rod down to the bottom of the groove, and the groove is 5/8ths deep. 
It might be a good idea to try it with 3/4 plywood, and let the sledge make the groove a little bit deeper than 5/8ths, then when you install the fin over the tube, use clamps like the ones Tom uses to push the excess into more wrap around the tube. I made a wood version of Tom's clamp that looks like this:
http://www.builditsolar.com/Experimental/CopperAlumCollector/FinClamp.htm
Its not as compact or fast as Tom's clamps, but it works fine. I've only done a small 2 ft test find with it, but it seems to work fine. I plan to use it on my new 100 sqft collector.

All this said, the way that Woodsy and I and Kevin did the grooves also works fine. This is Kevin's method:
http://www.builditsolar.com/Projects/WaterHeating/Kevin1KSystem/KevinSystem.htm

I think that the main thing is that when you are done, is that the fin is in tight contact with the copper, and that if there is a little gap here and there that the gap is paper thin.

Gary


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## woodsy (Oct 13, 2008)

As a testament to the effectiveness of a well made, well insulated solar collector, I did a collector stagnation(dry, no water flowing) temperature test this morning. At 10:45 the outside air temp was 8 degrees, the sun under clear skies was close to perpendicular to the panels ,within about 1/2-1hr. and the temperature in the top of the panels was 206 degrees !!!
Gary, I have not forgotten the system review i promised, but decided to hold off and do an annual summary (May-June) time frame. That way i will have a good average as to the effectiveness and cost savings over a years time.


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## SolarGary (Sep 8, 2005)

woodsy said:


> As a testament to the effectiveness of a well made, well insulated solar collector, I did a collector stagnation(dry, no water flowing) temperature test this morning. At 10:45 the outside air temp was 8 degrees, the sun under clear skies was close to perpendicular to the panels ,within about 1/2-1hr. and the temperature in the top of the panels was 206 degrees !!!
> Gary, I have not forgotten the system review i promised, but decided to hold off and do an annual summary (May-June) time frame. That way i will have a good average as to the effectiveness and cost savings over a years time.



Sounds good -- Thanks!

Gary


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## krysto (Jan 18, 2010)

Gary - On the attached image of your jig, the part that I circled in red - is that bolt the pivot point? And do you have the same thing on the other side?












SolarGary said:


> I made a wood version of Tom's clamp that looks like this:
> http://www.builditsolar.com/Experimental/CopperAlumCollector/FinClamp.htm
> Its not as compact or fast as Tom's clamps, but it works fine. I've only done a small 2 ft test find with it, but it seems to work fine. I plan to use it on my new 100 sqft collector.
> 
> Gary


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## krysto (Jan 18, 2010)

Really cool jig by the way!


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## SolarGary (Sep 8, 2005)

Hi,
Yes -- the bolt is a pivot, and there is another one on the other side.
I should have put a little more description in -- or maybe have a picture with it closed and another with it open.

Gary


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## krysto (Jan 18, 2010)

In the jig photo - is it in the maximum "clamping" position? The handle is as far down as it goes, so this seems like the maximum position. Did you design it so that in maximum clamp position it will be just enough to squeeze the fin just the "right amount"? I suppose I might have made it so that I can squeeze until it can't squeeze anymore - that is, have the fin tell me when to stop rather than the handle bumping up against the jig. Does that make sense?


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## SolarGary (Sep 8, 2005)

krysto said:


> In the jig photo - is it in the maximum "clamping" position? The handle is as far down as it goes, so this seems like the maximum position. Did you design it so that in maximum clamp position it will be just enough to squeeze the fin just the "right amount"? I suppose I might have made it so that I can squeeze until it can't squeeze anymore - that is, have the fin tell me when to stop rather than the handle bumping up against the jig. Does that make sense?



Its set up to squeeze the fin tightly against the tube -- I don't think that it could be made much tighter without breaking something. 
But, you can adjust the tightness by moving the cam shaped piece of wood.

Gary


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## Virgil (Sep 29, 2009)

Thermal Steam Blow-Off
A quick reply to the method of circulating water through a very hot wood stove. 
Several years ago, late 70's, we set up a wood burning furnace of which we circulated both hot air and hot water through it for heat. It is absolutely true that stagnated water inside a hot wood stove can quickly turn into a thermal bomb. We had this system tied into our existing oil furnace baseboard heating system. While the wood stove was producing heat the pressurized water needed to be circulated constantly. One day while working in my cellar shop we temporarily lost electric power. The wood stove was up to normal operating temperature. Within seconds both pressure temperature relief valves opened one located at the wood stove and the other at the furnace. Despite both these valves opening the interconnecting 3/4" copper line between the wood stove and the furnace flexed enough to crack the pipe. I also opened up a manual relief valve once I found a flashlight in the dark. The house filled up with steam and luckily the damage that time was minor. It was a good thing that I was there when this happened or the damage may had been more. Beware, circulating pressurized water through a wood stove is potentially a bomb. 

Virgil


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## krysto (Jan 18, 2010)

Tom Sullivan told me that he would use a 3/4" steel rod to pound the groove in the aluminum to eventually wrap around 1/2" copper pipe (if he still used the pounding method, which he does not since he made a press). That gives more material to wrap around the pipe with his vice grip tool.

How does that sound? My naive impression, not having tried this yet, is that I might end up with too much material to wrap around the pipe.

Thom



SolarGary said:


> Hi,
> I used 5/8ths plywood, so in my case, the sledge pushes the metal rod down to the bottom of the groove, and the groove is 5/8ths deep.
> It might be a good idea to try it with 3/4 plywood, and let the sledge make the groove a little bit deeper than 5/8ths, then when you install the fin over the tube, use clamps like the ones Tom uses to push the excess into more wrap around the tube. I made a wood version of Tom's clamp that looks like this:
> http://www.builditsolar.com/Experimental/CopperAlumCollector/FinClamp.htm
> ...


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## SolarGary (Sep 8, 2005)

krysto said:


> Tom Sullivan told me that he would use a 3/4" steel rod to pound the groove in the aluminum to eventually wrap around 1/2" copper pipe (if he still used the pounding method, which he does not since he made a press). That gives more material to wrap around the pipe with his vice grip tool.
> 
> How does that sound? My naive impression, not having tried this yet, is that I might end up with too much material to wrap around the pipe.
> 
> Thom


Hi,
There is a picture of some plates that Ton did in this way on his latest project posted on BuildItSolar -- they look good to me.

I would guess that the performance of the ones formed with a 5/8ths rod and with the flat alum strip under the center of the copper tube would be close in performance to Tom's fins formed on a 3/4 inch rod.

Gary


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## woodsy (Oct 13, 2008)

The 1K DIY solar hot water system has been in use for a year now and the results are very good.
The elec. bill dropped $399.00 (2,665 KWH) from the previous year .

Its all automatic except in the winter when we flow water through the wood stove coil which is manually turned on/off.

Looking forward to $8,000.00 in savings over the next 20 years :buds:

Thanks to Gary and Build it Solar !

I should add( or brag) that our average monthly elec. consumption over the last 12 months was 505 KWH, (6060 yr.), that is slightly more than 1/2 the national average household usage but very close to average for this state.



> In 2008, the average annual electricity consumption for a U.S. residential utility customer was 11,040 kWh, an average of 920 kilowatt-hours (kWh) per month. Tennessee had the highest annual consumption at 15,624 kWh and Maine the lowest at 6,252 kWh.


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## SolarGary (Sep 8, 2005)

Nice!



woodsy said:


> The 1K DIY solar hot water system has been in use for a year now and the results are very good.
> The elec. bill dropped $399.00 (2,665 KWH) from the previous year .
> 
> Its all automatic except in the winter when we flow water through the wood stove coil which is manually turned on/off.
> ...


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## ChristieAcres (Apr 11, 2009)

DH is building us a solar water system that runs completely independently from our woodstove system (multiple pressure relief valves & also a light to confirm the pump is on). We won't be connecting them. The discussion of having the system on the roof... We are going to counter-balance over the peak, so no holes and won't need tied down. Due to where we are, we will only be using the solar water system in warmer months. During the colder ones, our woodstove system. This is a great thread to refer to


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