# Wood to Solar transition



## Nofossil (Apr 12, 2008)

Just about the end of the wood season for me - got heat from both wood and solar in the last 24 hours.

Graph show boiler heating storage tank, then storage tank heating house, then solar panels heating storage tank. One of my glazed panel suffered freeze damage. I was heating with only two until late in the day when I brought the third back online, too late to do much.


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## antknee2 (Apr 12, 2008)

It 's my first spring with this solar system taking over the job of DHW and the last of the heating requirement's . Very good feeling to capture some of the sun's awesome power and store it for  later use . My personal feeling is every home should have a DHW system to help supplement hot water needs .


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## heaterman (Apr 12, 2008)

What prompted your choice of evac tubes vs regular panels?

I agree that a well engineered and integrated solar collector should be included in all heating systems.


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## antknee2 (Apr 12, 2008)

heaterman said:
			
		

> What prompted your choice of evac tubes vs regular panels?
> 
> I agree that a well engineered and integrated solar collector should be included in all heating systems.



What I like about the tubes is there ability to produce very high temperatures in the dead of the winter all they need is a clear day and some sort of storage system that exchanges with main heat loads .
The other reason I like the EV tubes is I tend to work by my self and all the parts are light weight and easy to assemble especially on a flat roof only 13' off the ground . There are allot of parts.  Anthony


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## BrownianHeatingTech (Apr 13, 2008)

Anthony D said:
			
		

> The other reason I like the EV tubes is I tend to work by my self and all the parts are light weight and easy to assemble especially on a flat roof only 13' off the ground



Aside from the efficiency, this is a big plus for do-it-yourselfers and contractors, alike.

I don't want to think about the liability involved in installing a multi-hundred-pound traditional panel on a roof using only ladders, or the equipment rental costs to get power scaffolding involved.  Evacuated panels go up in little, lightweight pieces.  The heaviest component is the manifold, and I don't think that weighs more than 50 pounds...

We put up a 30-tube Thermomax panel in the dead of winter on a standing-seam metal roof, a few months ago.  Got the system up and running with no trouble at all.

By the way, to anyone looking to do solar, check out Caleffi's SolFlex piping system.  Two flexible stainless steel pipes and a wire for the collector sensor, insulated and wrapped with armor.  It's like working with PEX, and greatly simplifies things compared to rigid pipe.  We were able to come out the end wall and wrap up over the edge of that metal roof, rather than having to penetrate the roof and risk a leak.  I can't say enough good about this stuff.  Saved a lot of man-hours and a lot of liability, even on a small, single-collector job like that.  Other than a big commercial installation, I can't imagine that I will ever pipe solar with rigid pipe again.

Joe


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## wdc1160 (Apr 13, 2008)

Anthony D,  I really think that your approach of year round mitigation of energy requirement is the model I would like to emulate.  One thing that would be awesome would be if you could estimate output.  You know the real world performance.


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## SteveJ (Apr 13, 2008)

Anthony,

Thanks for the pictures...

Questions (as usual   ):

1. Is the chimney in the first picture for the Seton? If so, what type of cap are you using?

2. When did you get the solar tubes installed?

3. Did you do any estimate of a payback period on the solar?

4. Did you get the Federal Tax Credit?

Thanks as always and nice job!!
Steve


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## SteveJ (Apr 13, 2008)

nofossil,

In your graph, is the first dip in the "Solar In" due to reverse thermosiphoning?

Do you run the solar panels all winter or drain the system?

Thanks,
Steve


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## antknee2 (Apr 13, 2008)

ABGWD4U said:
			
		

> Anthony D,  I really think that your approach of year round mitigation of energy requirement is the model I would like to emulate.  One thing that would be awesome would be if you could estimate output.  You know the real world performance.



I agree with you 100% , A new differential controller that has energy calculation capabilities is on my wish list , would be even better if the data could be downloaded to a computer . Any suggestions or recommendations would be very much appreciated .The Goldline GL 30 is a great controller , which is in service on this system , only problem no data .

Any thoughts on this controller 
http://www.thermomax.com/BTU_Meter.htm
Thanks Anthony


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## antknee2 (Apr 13, 2008)

SteveJ said:
			
		

> Anthony,
> 
> Thanks for the pictures...
> 
> ...



Hi Stevej good to hear from you .
The camo green chimney is for the Seton .
The solar system went on line the first or second week of 01/2008.
Pay back for me is had to calculate because we have always use free wood to heat this house and work shop . We will save about 600 gallons of fuel oil for DHW and keeping my home brew endless pool at 83 degrees F all year.
We did not take a tax credit ,my accountant acted weird when we talked about the subject .


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## Nofossil (Apr 13, 2008)

SteveJ said:
			
		

> nofossil,
> 
> In your graph, is the first dip in the "Solar In" due to reverse thermosiphoning?



No - it's the not-quite-famous 'cold lock' phenomenon. When the panels start to heat up first thing in the morning, there's a slug of cold water in the lines between the panels and the storage. This cold slug has to be pushed through the system before hot water can flow. I provide a bypass for it, but it has to happen nonetheless. The sensor is right at the storage inlet, so it sees the cold slug passing by.



> Do you run the solar panels all winter or drain the system?
> 
> Thanks,
> Steve



I drain them. If it's cold enough for the panels to freeze, then I'm burning wood and I don't need the panels. During the winter, the best I could hope for from the panels if I optimized everything would be only enough to offset half an hour of wood burning on a good day - hardly worth the aggravation.

I'm an inveterate cheapskate. My total solar investment in panels, plumbing, controls, instrumentation, and heat exchangers is about $200. Payback was pretty quick. It provides 100% of my hot water needs June through August, and better than 75% during the shoulder months. Wood provides 100% mid October through mid April.


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## drizler (Apr 13, 2008)

nofossil said:
			
		

> SteveJ said:
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## wdc1160 (Apr 13, 2008)

Anthony.  The primary thing this controlller lacks is logging.  Take it from a computer scientist, they made logs for a reason.  We don't want to hover over our equipment all day long.

I am so interested in the outcome of this antony I would send you a controller.  I just havne't found one that is user friendly.  I have been working with a similar controller to Nofossil's.  But, for people who don't want to learn the finer points of php and linux, its not likely a good fit.  I wanted to contribute to the board by donating a setup script of a controller like nofos.  And, I still think I will, but I haven't found the time yet.  

I will have more time to wrestle with an answer to the question after april 15.  


I really have spent most of my controller time on my controller.  Maybe someone can find a simplier controller that has logging.  PS If you'll notice from nofo's logs we can see most aspects of his energy use.  He happens to put his data in graph from which helps analysis, but I think even a txt file would help enormously.  We could turn the txt into a graph easily enough.  I am getting off topic.  

in summation, the btu meter you show has only a delta t of 50F, which I think is a deal breaker, and no logging.  Which means that at best its not a controller, just a bad sensor.

I will spend a couple hours on Wed or TR looking at the problem.


Thanks for your pioneering and sharing anthony.


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## VeggieFarmer (Apr 14, 2008)

NoFo: I friend of mine says I should plumb the solar coil into the dhw tank, not into the main storage tank, because the main storage tank will never get hot enough from my two panels to make dhw. I recall you writing that the stratification in the main tank is more than adequate, and I notice that the goal of your first mixing valve is to prevent the main tank water from scalding the shower occupants. Did you always have it set up this way, or did you start off running your solar into the dhw tank?  

From another angle, if you're draining the solar in the winter, and not using/needing the big storage tank in the summer, why not just go straight from the solar to the dhw? (Do you think you're getting enough heat off the panels in the shoulder season to make it worth it?) Thanks.


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## Nofossil (Apr 14, 2008)

VeggieFarmer said:
			
		

> NoFo: I friend of mine says I should plumb the solar coil into the dhw tank, not into the main storage tank, because the main storage tank will never get hot enough from my two panels to make dhw. I recall you writing that the stratification in the main tank is more than adequate, and I notice that the goal of your first mixing valve is to prevent the main tank water from scalding the shower occupants. Did you always have it set up this way, or did you start off running your solar into the dhw tank?



I've always had it set up this way. Part of the issue is that I can thermosiphon from the panels to the big storage tank, but my DHW tank is too low. If I could design my ultimate system, the panels would heat the DHW tank first, then the big storage tank. This would require the DHW tank to be above the storage tank. With three glazed panels and an above-ground pool heater, I got the top of my 880 gallon storage tank above 150 degrees last summer.



> From another angle, if you're draining the solar in the winter, and not using/needing the big storage tank in the summer, why not just go straight from the solar to the dhw? (Do you think you're getting enough heat off the panels in the shoulder season to make it worth it?) Thanks.



It's the thermosiphon problem mentioned above. I do get quite a bit of usable heat even in the shoulder months. I was getting 150 degree water off the panels yesterday, for instance. Had to drain them today, though. Supposed to be upper 20's tonight, and lower 20's tomorrow night.


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## BrownianHeatingTech (Apr 14, 2008)

ABGWD4U said:
			
		

> Anthony.  The primary thing this controlller lacks is logging.  Take it from a computer scientist, they made logs for a reason.  We don't want to hover over our equipment all day long.
> 
> I am so interested in the outcome of this antony I would send you a controller.  I just havne't found one that is user friendly.  I have been working with a similar controller to Nofossil's.  But, for people who don't want to learn the finer points of php and linux, its not likely a good fit.  I wanted to contribute to the board by donating a setup script of a controller like nofos.  And, I still think I will, but I haven't found the time yet.
> 
> ...



Resol controllers have always worked well for me, and offer data logging (with an external data logger that is attached to the controller).

They are re-sold by a number of companies.  I happen to use Caleffi as a supplier, because I buy most of my other solar piping and controls from them...
http://www.caleffi.us/en_US/caleffi/Details/News/files/257_Series.pdf

That file doesn't show the data logger, but if you look for the Resol data logger on the web, I'm sure you can find it...

Joe


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## ISeeDeadBTUs (Apr 14, 2008)

BrownianHeatingTech said:
			
		

> We put up a 30-tube Thermomax panel in the dead of winter on a standing-seam metal roof, a few months ago.  Got the system up and running with no trouble at all.
> 
> Joe



Joe. . . . I have 16" seams, what sort of mounting hardware is available? How much wind can it withstand? Does anyone make a mounting system that would reposition the panel as the sun progresses throughout the day? 

Jimbo


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## Moosestache (Apr 14, 2008)

I always wondered about the possible payback on a solar system if you are using a wood boiler.  Solar vs oil at $3 or more seems like the payback would be quick, solar vs wood seems like the payback would take quite a while.  I guess it depends on how much the solar system costs, and how much of your summer hot water costs are, if you decide to stop using your wood boiler.  What kinds of costs should one expect to put in a solar system to cover the "shoulder" and summer months, and hopefully do away with oil usage almost completely?  Thansk


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## VeggieFarmer (Apr 14, 2008)

Moosetache: some of these questions are discussed at the following thread (though I'm sure there's more to say): https://www.hearth.com/econtent/index.php/forums/viewthread/14272/


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## BrownianHeatingTech (Apr 14, 2008)

ISeeDeadBTUs said:
			
		

> Joe. . . . I have 16" seams, what sort of mounting hardware is available?



Depends on your roof pitch.  This was a 6/12 pitch.  For summer performance, you want the panels to match your latitude.  For winter performance, check a solar chart.  In this case, we wanted to enhance winter performance, to provide a small amount of backup space heating as well as to avoid overheating the tank in the summer, so we decided on an angle around 60 degrees.  To mount the panels, we used a flat roof frame (similar to what's shown in the pictures in this thread) to bring the panels up at a steeper angle than the roof.



			
				ISeeDeadBTUs said:
			
		

> How much wind can it withstand?



I've never heard of a problem with wind.  The evacuated tubes let a lot of the wind flow right through.  For actual wind performance numbers, I'd contact the manufacturer.

To mount the "feet" of the frame, we used lag bolts into the strapping under the metal roof, which held everything nice and steady, then we drilled through the roof and used stainless bolts with nuts and fender washers inside the attic.



			
				ISeeDeadBTUs said:
			
		

> Does anyone make a mounting system that would reposition the panel as the sun progresses throughout the day?



Theoretically, you could use one of those trackers that they make for PV panels, and use the flexible piping to allow it to move the panel around, but you might fatigue the piping.

But there really wouldn't be much benefit, with the efficiency of the evacuated tubes.  They pull in a lot of solar energy, and you can turn each individual tube during installation so that it points due south, even if the roof isn't exactly dead-on south-facing.  I don't think there would be a benefit to tracking.  I've seen systems where the roof ridge was north-south, where they put a panel on each roof, and use a controller to just switch panels as the sun moved.  If you had a roof facing east, one facing south, and one facing west, I suppose you could cycle through the panels as they heated up, and avoid the maintenance issue of a tracker and flexible piping getting continuously flexed.  In the long run, that would probably be cheaper than maintaining a tracker.

Now, being able to vary the pitch of the panels between summer and winter would be a benefit.  I think I'll be doing that when I put mine in either this summer or next.  I'll manufacture my own frame with hinges and such to allow for that, and have a few "stops" in the adjustment, so I can move it a few times during the year as the sun's angle changes.  During the summer, the panels will be just barely steeper than my 12/12 roof (since the latitude is roughly 43* here), and during the winter they will be able to go all the way up to 70* or so.  I'll probably just have it work with a hand-crank, since I can walk out onto the roof from one of my windows.  Remove the pins, crank it up or down, and they re-install the pins at the new angle.

Joe


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## wdc1160 (Apr 14, 2008)

anthony,

The Resol RESOL DL1(logger)  that Brownian Heating tech mentions does log and save to PC.  However, It won't log anthing except 1 thermostat from what I can tell.

I am still looking at them.


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## BrownianHeatingTech (Apr 14, 2008)

ABGWD4U said:
			
		

> The Resol RESOL DL1(logger)  that Brownian Heating tech mentions does log and save to PC.  However, It won't log anthing except 1 thermostat from what I can tell.
> 
> I am still looking at them.



Hmm... I'll check with them when I get a chance, since I thought it logged more than that.  I've never had reason to use one.

Of course, the controllers communicate by a RS232 serial signal, IIRC, so it might be possible to just connect directly...

Joe


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## Bob Rohr (Apr 14, 2008)

Crunch the numbers carefully when comparing evac tubes to flat panel collectors.  Yes they may be easier to install, and they may provide a bit higher temperatures.  

If you run the calcs over a year with a good program using daily radiation, like Maui Solar, you'll be hard pressed to find a 10% difference in performance.  At close to 3 times the cost adding additional flat panels would give you better performance, at a much lower cost.

What the evac tubes bring to the table is a more efficient insulation, the vacuum between the glass layers.  But the bottom line is there just isn't much energy to harvest from a cold winter sky.  Go to the NASA website and plug in your location to see the  Solar Energy Available Tables to compare December, to July for example.  And notice the amount of energy available in December for your area.

The more efficient insulation offered by the evac tubes over the flat panels can't make up for the lack of energy available, regardless of how they spin the numbers.

The performance of any collector has the most to do with the conditions that the load presents to them.  Mainly the ambient air temperature, and the fluid temperature returning to them.  Low temperature radiant emitters are a better match for solar than higher temperature fin tube baseboard, for example.

 As you can see on this graph based on ASHRAE 93-77 data the un-glazed pool collectors will outperform both flat panel and evac tubes at the right conditions.

By their own admission the evac tube manufacturers projected a 10 year realistic life span.  Newer models with better seals are looking for 15 years.  Quiz the manufacture about the warranty with any panel or tube.

I visited with a bunch of solar contractors in Denver this weekend.  One told me of a 100 tube array installed 5 years ago that has had 25 tubes failures, lost vacuum.  A very un happy customer.

I have 20 year old flat panels on my home and shop that are collecting as well as they did 20 years ago.

I believe there is a place for the evac tubes, under the right conditions, just be sure to do the numbers by the data available at the SRCC.  To say they are better under all conditions???

here is a free download that will help with your solar planning and design.

http://www.caleffi.us/caleffi/en_US...gazine_detail_0000063/type/magazine/index.sdo

 hr


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## BrownianHeatingTech (Apr 14, 2008)

master of sparks said:
			
		

> Crunch the numbers carefully when comparing evac tubes to flat panel collectors.  Yes they may be easier to install, and they may provide a bit higher temperatures.



The temps are the big thing.  Capturing energy isn't meaningful, if the absolute temperature is too low to put it to use.  Efficiency numbers that don't take that into consideration aren't helpful.



			
				master of sparks said:
			
		

> By their own admission the evac tube manufacturers projected a 10 year realistic life span.  Newer models with better seals are looking for 15 years.  Quiz the manufacture about the warranty with any panel or tube.
> 
> I visited with a bunch of solar contractors in Denver this weekend.  One told me of a 100 tube array installed 5 years ago that has had 25 tubes failures, lost vacuum.  A very un happy customer.



Which manufacturers say that?

Thermomax tubes have a 10-year warranty, and are likely to last at least twice that, if not longer.

Actually, the last shipment I got was dropped and speared with a forklift by the freight company.  Of 30 tubes, one was damaged.  It had the condenser end sheared right off it.  Still had vacuum integrity (and still does, sitting in the corner of my shop, a couple months later).



			
				master of sparks said:
			
		

> I believe there is a place for the evac tubes, under the right conditions, just be sure to do the numbers by the data available at the SRCC.  To say they are better under all conditions???



I would hope no one would say that...

Joe


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## wdc1160 (Apr 14, 2008)

Master,  Awesome link, here is another helpful link that I found on that same page

http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_3_us.pdf


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## SteveJ (Apr 14, 2008)

Here is a link to a comparison of flat plate and evacuated tubes used all year in a freezing climate:

http://www.solarh2ot.com/images/Performance%20-%20Flat%20Plate%20vs%20Vacuum%20Tube.pdf


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## wdc1160 (Apr 14, 2008)

Steve,  If you read that close, they are testing with the evac tubes cover with snow.  That maybe  real world test, but in central indiana it doesn't represent what is normal.  Especially if you put the evac tubes at 70 degrees raise.  I am not sure those give graphs give me a good representation of what I can expect here in IN.  Anthony's expereince only underscores that.  He has stories were he simply create too much heat in some cases.  Your thoughts?


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## BrownianHeatingTech (Apr 14, 2008)

ABGWD4U said:
			
		

> Steve,  If you read that close, they are testing with the evac tubes cover with snow.  That maybe  real world test, but in central indiana it doesn't represent what is normal.  Especially if you put the evac tubes at 70 degrees raise.  I am not sure those give graphs give me a good representation of what I can expect here in IN.  Anthony's expereince only underscores that.  He has stories were he simply create too much heat in some cases.  Your thoughts?



Exactly.  If you keep them clean, they work great.  If you don't keep them clean... well, the reason that flat plate collectors stay clean is because they are wasting heat to melt the snow.  I'd rather just run a foam-edged roof rake over them to knock the snow off.  And, like you said, the angle will help to reduce that.  As will using a frame to keep them elevated from the roof more.

Joe


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## antknee2 (Apr 14, 2008)

BrownianHeatingTech said:
			
		

> ABGWD4U said:
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Bill & Joe thank you very much for your input and links . I am starting to realize that without any data logging I have no clue what happens during the day especially with the solar energy produced . Like today , perfect clear day I figured the tanks temps would be around 170-180 . Not today 140 F , but pool temp up 4 degrees , if the return water temperature to the solar system rises to 190 F it triggers pool heater zone to kick in . All other zones are set very low . Go figure ??


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## wdc1160 (Apr 14, 2008)

Anthony,  from your observations I know those things are going to make you pool boil this summer.   I don't know how big your pool is, but raising even 15K gallons(small pool) 4 degrees is alot of heat. You can do the math.   I think the newest era solar evac tubes must be just ridiculous.  I am more intersted in real world winter doability.

As an example if you system inthe winter could do 50000 btu on a clear day in winter - half of purported daily output.  That may be able heat my house even at 30F during winter- an almost certainly heat my house at 40.  If I turn down certain zones it could even fare better.  Now all I have to do is learn how to eliminate cloud cover??


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## Bob Rohr (Apr 14, 2008)

BrownianHeatingTech said:
			
		

> master of sparks said:
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## Bob Rohr (Apr 14, 2008)

ABGWD4U said:
			
		

> Master,  Awesome link, here is another helpful link that I found on that same page
> 
> http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_3_us.pdf



A solar webinar will be presented May 1 also, sponsored by Caleffi, and presented by well know hydronic and solar guru John sigenthaler.  A bargin at 49 bucks if solar is in your plan.

hr

http://www.caleffi.us/caleffi/en_US...s~news_detail_0000391/type/newshome/index.sdo


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## Bob Rohr (Apr 14, 2008)

BrownianHeatingTech said:
			
		

> ABGWD4U said:
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Is it realistic to expect the homeowner to "rake" off their solar collector after snowfalls?  Just make sure they don't snag the clips that hold they onto the rack  

 hr


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## wdc1160 (Apr 14, 2008)

I guess, it depends on where the solar panel is located.  But, I don't have snowfall like many of you do.  Although It does get cold and windy, I am located in a place where snow fall is a minor nuisance.  I don't know where the testing took place.  I just know the average winter day in Lafayette doesn't include any snow.  When it does, it usually melts quickly due to ambient temps.  

My hurdle is my local government rapes me on Nat gas prices.  So on a btu per dollar basis, people in Chicago pay much less than I do.  They are working on a way to tax the sun, but so far have become unsuccessful.  

Although you point is valid, the test doesn't hold true to my locality.


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## steam man (Apr 14, 2008)

I haven't been on for a while since I am traveling and currently in Puerto Rico for a short stay. I have 9 older flat plate collectors that have yet to be installed (and may not) but just purchased a 120 evacuated tube system. I am waiting on a re-roofing this spring. I am considering doing a hybrid setup to actually study the differences over time between the two systems or just adding another 60 tubes to get where I would like to be. I am running out of roof space. I've looked at the resol controller and thought of using the setup for an east-west panel system for a flat plate/evacuated tube system with data logging. I've read the research on the winter verses the summer performance and it intrigues me. The ease of installation of the evacuated tubes sort of swings me to that side. Not only that but I plan to add the tubes to utilize the heat as I build the system I want in stages. The heating calculations tell me that I would need add quite a few more tubes for pool heating. I think I am about 40-50% on space heating with the 120 tubes but there are no guarantees with anything. I am also looking at data logging but haven't decided on any one setup yet. I do have an interesting concept design for the solar and wood boiler heating combination. When I get it fully drawn out I will let you guys "rip" it apart. LOL. 

I just blew a safety valve on a large marine boiler coming into port today. It wasn't one of my finer moments. %X#%^&*


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## steam man (Apr 14, 2008)

I just saw the picture of the panels with the snow cover. I can have 3 ft of snow on my roof easily. I plan on raising the feet up somewhat higher off the roof and maximizing the angle for snow shedding and winter heating. The wind load is something I will take into consideration. I have also looked at somehow adjusting the angle of the panels for different seasons but the risk of panel damage and complexity for a large array along with the cost leads me to believe it would be easier just to add extra panel area for summer use with a larger tilt angle for winter. Certainly I should have the summer covered.


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## Bob Rohr (Apr 14, 2008)

One nice thing about evac tubes is you can easily remove some to adjust summer output.  I built some racks on the ceiling of my shop to store "off season" tubes. 

 Solar contractors with snow country experience tell me at least a 45 pitch to help with snow slide. Another suggested some of those windshield waxes to help the snow slide off the tubes.

I've seen pictures of evac tubes in a vertical position also.  The U of Maryland Decathlon home had an Apricus array mounted vertically.  Although the winning home had flat panels 

I'm still researching longevity issues with evac tubes.  I have talked with longtime solar installers in Colorado, New Mexico, and North Carolina recently, trying to get a feel for tube reliability.  I'm still researching, but all three tell me tube replacement is a real consideration.

You can get more absorber plate per square foot on the roof with panels when you consider the space between the tubes, the vacuum space,  and the header.

The Apricus website shows tubes on pole mounted tracking racks if you really want to maximize the solar window 

 hr


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## antknee2 (Apr 14, 2008)

ABGWD4U said:
			
		

> Anthony,  from your observations I know those things are going to make you pool boil this summer.   I don't know how big your pool is, but raising even 15K gallons(small pool) 4 degrees is alot of heat. You can do the math.   I think the newest era solar evac tubes must be just ridiculous.  I am more intersted in real world winter doability.
> 
> As an example if you system inthe winter could do 50000 btu on a clear day in winter - half of purported daily output.  That may be able heat my house even at 30F during winter- an almost certainly heat my house at 40.  If I turn down certain zones it could even fare better.  Now all I have to do is learn how to eliminate cloud cover??



The pool is only 14 x 8' x 4' deep very well insulates and always covered with 2'' styro foam panels , they float on the water . The pool is indoors . Bill you have a good point about overheating the pool if the water is over 83 degrees that would make my workout allot harder . Cool water is the way to go .


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## Nofossil (Apr 15, 2008)

If you don't heat with wood, I guess it might make sense to look at really expensive high-performance solar collectors that can heat your DHW in the midst of winter.

On this forum, though, I'd assume anyone with enough ambition to do solar is already heating DHW with wood during the winter. In that case, a much less expensive and exotic solar system can easily provide DHW during the summer months.

I just built my last fire, and starting in about two days, I expect to get very nearly 100% of my DHW from my el cheapo solar panels.


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## antknee2 (Apr 15, 2008)

Supplementing with solar as a boost to you thermal storage system is a definite wild card when it comes to predicting what your energy requirement for the day in the winter . I will admit on the very clear days when you see the solar system keeping up and then some with you heating requirements , it will bring a smile to your face and save some wood .


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## Nofossil (Apr 15, 2008)

Anthony D said:
			
		

> Supplementing with solar as a boost to you thermal storage system is a definite wild card when it comes to predicting what your energy requirement for the day in the winter . I will admit on the very clear days when you see the solar system keeping up and then some with you heating requirements , it will bring a smile to your face and save some wood .



We have plenty of southern facing glass. If it's calm, sunny, and over 20 degrees we don't need any heat during the day. Nighttime is another story, but I don't think even the best solar collectors do much with moonlight ;-)

My solar panels put out something in the order of 100,000 BTU/day in early summer. If I could protect them from heat loss to the environment, they still wouldn't do more than a third of that on the best winter days, when I don't need heat anyway. Mostly when I need heat it's cloudy and/or dark. 30,000 BTU is less than 1/2 hour of boiler operation. I did a back-of-the-envelope calculation and decided that even an ambitious solar system would save me only a fraction of a cord of wood per year. I put the money in a gasifier instead, and my next investment is a radiant zone.

Again, my choices are based on my situation. Others may arrive at different conclusions. It would be interesting to put together a budget guideline / spreadsheet providing some sort of roadmap about what investments have the best return: If this is your situation and you have X to spend, this is a likely best approach. For instance, insulation is probably the best investment up to a certain level, then better windows, and so on. Wood stoves, conventional boilers, gasification boilers, solar DHW, solar heating, PV, and other goodies fall in at different points along the continuum.


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## Bob Rohr (Apr 15, 2008)

good points NoFo.  A solar array that would supply even a small portion of a winter heating load will turn into an overheating machine in the summer.  How much would one spend to purchase a 6-8 month system.  A 4X8 panel may only provide 20K per DAY

It may be that a PV system with it's year around energy use potential, and buy back, net metering from the power company, may be a better investment for some.

 hr


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## BrownianHeatingTech (Apr 15, 2008)

master of sparks said:
			
		

> Is it realistic to expect the homeowner to "rake" off their solar collector after snowfalls?



Yes.  Most folks around here own roof rakes, and rake their roof anyway, so why not rake the panel while they're at it?



			
				steam man said:
			
		

> I have also looked at somehow adjusting the angle of the panels for different seasons but the risk of panel damage and complexity for a large array along with the cost leads me to believe it would be easier just to add extra panel area for summer use with a larger tilt angle for winter. Certainly I should have the summer covered.



If you look at the pictures of how the frames work, back on the first page of the thread, it's pretty easy to just un-bolt the brace and re-bolt it at a different angle (provided that you design your braces slightly different from the ones shown in that picture, so the angle-iron doesn't interfere with the panel.



			
				master of sparks said:
			
		

> Another suggested some of those windshield waxes to help the snow slide off the tubes.



I like that idea, although it would probably want to be done after installation, to avoid dropping tubes while handling them...



			
				master of sparks said:
			
		

> I'm still researching longevity issues with evac tubes.  I have talked with longtime solar installers in Colorado, New Mexico, and North Carolina recently, trying to get a feel for tube reliability.  I'm still researching, but all three tell me tube replacement is a real consideration.



What brand tubes are they using?  I've never heard of a failed Thermomax tube (except the one that the freight company broke).  I had (at the time) two suppliers for the tubes, and they were both scratching their heads on how to get me a single tube, because they had literally never had to ship out a replacement tube before.  One had to replace a whole box of ten tubes that got rolled-over by a truck, but never any for repair use.  I ran into a similar problem when I first started carrying these things, and I wanted a single tube to use as a demonstration model for home shows and the like.

I always tell my customers that, if a tube ever breaks due to natural causes (except not something like a tree falling on the house, which would break anything, flat-plate or evacuated), I'll replace it free of charge.  I don't expect to ever need to honor that warranty.

Joe


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## BrownianHeatingTech (Apr 15, 2008)

nofossil said:
			
		

> I did a back-of-the-envelope calculation and decided that even an ambitious solar system would save me only a fraction of a cord of wood per year.



Personally, on a residential scale, I don't think solar (when purchased retail and installed by a contractor) will actually have a reasonable return on investment.  If you do it yourself, as you did, then it can.

I sell the stuff, but I don't tell my customers that it will pay for itself.  The ones who have done solar have done it because they like the idea of solar and the convenience of using little or no fuel during the summer.  At current technology costs and fuel costs, solar is something that you do because you _want_ solar, not because you think that it will save you massive amounts of money.  If it does return on the investment and saves you something, that's a bonus.

There's nothing wrong with doing something for those purposes.  Look at central air.  It's not likely to save you money - quite the opposite.  But a lot of people still have it for the convenience and just because they want it.

Joe


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## Bob Rohr (Apr 15, 2008)

BrownianHeatingTech said:
			
		

> master of sparks said:
> 
> 
> 
> ...


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## BrownianHeatingTech (Apr 15, 2008)

master of sparks said:
			
		

> Joe, at the next RPA get together just start asking the members that specialize in solar for their experience with tubes.  I'm sure they will share brand, % of failures, location and pictures if you would like.  I'm not here to flame manufacturers in a public forum.  The data is real, and it's out there.  Or ask the people that make evac tubes, they should give an honest answer, they have the numbers as they send out the replacements.  If not the installers doing the replacements will



Drop me an email with the info, if you don't mind.  It's good to know what issues may exist, if someone asks my opinion on Brand X.  I know some are such low quality that they actually ship spare tubes with the panels.  Others are such high quality that (as I mentioned), they don't even know how to go about ordering a replacement tube.



			
				master of sparks said:
			
		

> Kudos for you for taking care of any warranty issue for your customer, regardless of the cause, that's the best policy you can offer.



My favorite kind of warranty is the one I don't expect to ever need to actually honor (not that I wouldn't, but I like warranting products that I expect to be highly reliable).

Joe


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## Bob Rohr (Apr 15, 2008)

As more and more of my customer starting asking about solar I set out to find out what products are out there and which have good track records.  It doesn't take long to figure out the  product info and reputation "spiel" you get from the sales and marketing folks differs somewhat, often greatly  from the info I recievied from the installers"in the field"

Furthermore as you discover how the sales and marketing personal move from company to company their  stories change dramatically.  Suddenly the previous brand they worked for had nothing but problems   Seems the company they currently work for is the one and only trouble free product   Do you have the same experience?  Really doesn't matter what the product is trucks, boilers, solar collectors, etc.  It's a common tale.

So I decided to start polling contractors I know with 20 years or more of hands on solar experience.  The more service experience they have, with solar, the better the data.  It's reallly the service contractors that get exposed to more of the problem systems.  Many times the original installers are long gone by the time the problems occur.

I noticed you are an RPA member and I know a dozen or more RPA members with many years of solar installation and repair experience.  Same with the gang at heatinghelp.com.  200 of us gathered in Denver last weekend to talk hydronics and solar.  It was a great place to meet face to face and get first hand experience from hands on folks.

I'm not looking to discredit one type or brand, just looking for real world experience.  You have the power of the keyboard to do this research, call on your peers, this is why we form and join associations.  Share the knowledge.  Knowledge is power and it buys you less headaches, many times.

When I hear lines like we don't know how to ship... because we never have had a failure, that make me wonder.  Doesn't it you?

hr


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## BrownianHeatingTech (Apr 15, 2008)

master of sparks said:
			
		

> Furthermore as you discover how the sales and marketing personal move from company to company their  stories change dramatically.  Suddenly the previous brand they worked for had nothing but problems   Seems the company they currently work for is the one and only trouble free product   Do you have the same experience?  Really doesn't matter what the product is trucks, boilers, solar collectors, etc.  It's a common tale.



Indeed.  That's one of the ways I've found to sort the professionals from the less-than-professional.

For example, I recently was talking to one of my suppliers about some material for a particular job.  They said, "well, I can sell you this, but [name of competing supply house] stocks [other brand], which will work better and be less money for you in this application."  This isn't the first time that they've done that for me.



			
				master of sparks said:
			
		

> I noticed you are an RPA member and I know a dozen or more RPA members with many years of solar installation and repair experience.  Same with the gang at heatinghelp.com.  200 of us gathered in Denver last weekend to talk hydronics and solar.  It was a great place to meet face to face and get first hand experience from hands on folks.



Sounds like a good time.  I haven't managed to travel anywhere out of the general area in many years.  If I did, I'd have to visit some family members as a higher priority than conventions, though.



			
				master of sparks said:
			
		

> I'm not looking to discredit one type or brand, just looking for real world experience.  You have the power of the keyboard to do this research, call on your peers, this is why we form and join associations.  Share the knowledge.  Knowledge is power and it buys you less headaches, many times.



Yeah... that's why I asked your opinion on the matter. 



			
				master of sparks said:
			
		

> When I hear lines like we don't know how to ship... because we never have had a failure, that make me wonder.  Doesn't it you?



Not in this case.  The response was the same from two completely separate companies (the first of which was the supplier mentioned above), and there actually isn't even a part number for a single tube in the manufacturer's catalog (or, at least, was not at that time - I haven't checked recently).

Joe


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## Bob Rohr (Apr 15, 2008)

Here is how I handle evac tube shipping.  This tube has traveled with me to numerous seminars, in my check on airline baggage!
I put one wrap of plastic bubble wrap around it.  This demo tube was shipped to me in the manufacturers box encased in foam blocks, as was the 8 tube array I installed on my shop.

With the info I have gathered to date, and the personal hands on experience I have, I feel comfortable in saying the flat panels have a much better longevity track record.  Consider also there are many more panel installatons than tubes in this country.

If the question is installation ease, yes, tubes do have an edge there.  Performance difference for my designs is pretty much a wash.  Return on investment IF both can go 20 years without a replacement, hands down the flat panels.  

Not all contractors are as generous as you with the 10 year no charge labor and parts replacement.  In the case I mentioned above with 25 tubes replaced in 5 years, even with a miniuum truck/ labor SOMEBODY has to pay for that.  Even with a free tube, there are costs to be absorbed.  Even a generous contractor, at some point has to question that business decision.

Just my 2 cents.  I'm off to install a tube system as we speak :0

 hr


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## BrownianHeatingTech (Apr 15, 2008)

master of sparks said:
			
		

> Here is how I handle evac tube shipping.  This tube has traveled with me to numerous seminars, in my check on airline baggage!
> I put one wrap of plastic bubble wrap around it.  This demo tube was shipped to me in the manufacturers box encased in foam blocks, as was the 8 tube array I installed on my shop.



Little different from an actual, full-length tube 



			
				master of sparks said:
			
		

> With the info I have gathered to date, and the personal hands on experience I have, I feel comfortable in saying the flat panels have a much better longevity track record.  Consider also there are many more panel installatons than tubes in this country.



There are a _lot_ of non-functional panels around here.  Seems that snow and ice plus flat glass equals... cracked panel.  I know of one individual who has literally replaced the glass after every winter.  The panel has been up for 15 years, and has had to have the glass replaced each of 15 springs.

Breaking a quality evacuated tube is very difficult.  It's strong glass, in the best possible shape for strength (other than a sphere, which would not be practical).



			
				master of sparks said:
			
		

> Not all contractors are as generous as you with the 10 year no charge labor and parts replacement.  In the case I mentioned above with 25 tubes replaced in 5 years, even with a miniuum truck/ labor SOMEBODY has to pay for that.  Even with a free tube, there are costs to be absorbed.  Even a generous contractor, at some point has to question that business decision.



Which is why it's important to choose quality products, which you won't actually have to warranty, because they won't fail.

Joe


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## Bob Rohr (Apr 15, 2008)

Sounds like your mind is made up, Joe.  Or you just like to argue 

I try to keep an open mind to options, which is one reason  why I installed tubes on my own place to get a true comparison.

I'd love to see that panel installation that need new glass every year, post a picture of the installation if you could.  That need to be in the Guiness book of records as possibly the only solar panel in the world that need yearly glass replacement.  Maybe that owner needs to reconsider his solar future. 

 Being a professional in the field I would think that would surprise you and offer a challange as to why, and how to correct.  It's glass over copper for crying out loud, not rocket science.  Schuco and Solar Skies both have pictures of people standing on their glass collectors.

 My 30 years experience with glass covered flat panels on 4 of my own homes and shops and hundreds of other customer installations has yet to present a broken glass.  My early Piper Hydro panels had a thin plastic covering and lasted for many years in the high mountains of Utah.

I did see one out a four panel array break with baseball sized hail a few years back in my area.  A fairly flat angle installation may have been part of it.

It's not the case of the glass breaking on evac tubes, as you mentioned that shape is very strong.  Their failure is typically loss of vacuum, although hail has been know to break even evac tube glass.

Another weak link in my mind is the dependency on the thermal transfer grease connection between the header and tube connection.  A lot of heat transfer "faith" is placed in that film.

 hr


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## BrownianHeatingTech (Apr 15, 2008)

master of sparks said:
			
		

> Sounds like your mind is made up, Joe.  Or you just like to argue



Not at all.  That's why I asked you to drop me an email with your findings.  I'm more than happy to learn something new...



			
				master of sparks said:
			
		

> I'd love to see that panel installation that need new glass every year, post a picture of the installation if you could.  That need to be in the Guiness book of records as possibly the only solar panel in the world that need yearly glass replacement.  Maybe that owner needs to reconsider his solar future.
> 
> Being a professional in the field I would think that would surprise you and offer a challange as to why, and how to correct.  It's glass over copper for crying out loud, not rocket science.  Schuco and Solar Skies both have pictures of people standing on their glass collectors.



The installation is not exactly nearby, so it's unlikely that I will be able to take photos of it any time soon.  The glass has broken under the snow and ice load every year.



			
				master of sparks said:
			
		

> It's not the case of the glass breaking on evac tubes, as you mentioned that shape is very strong.  Their failure is typically loss of vacuum, although hail has been know to break even evac tube glass.



And how does the vacuum fail?  Something has to break for that to happen.



			
				master of sparks said:
			
		

> Another weak link in my mind is the dependency on the thermal transfer grease connection between the header and tube connection.  A lot of heat transfer "faith" is placed in that film.



I guess that would depend upon the header design being used.  The Thermomax headers make pretty good metal to metal contact, so I doubt that the grease is doing all that much.  And the performance of heat transfer greases isn't exactly an article of faith; they've been used for many years in many different environments, for many different technologies.  Simple stuff, really.  And it's sealed inside the header, so there's not much to go wrong with it, once the tubes are installed.  I suppose if you pull some of the tubes each summer, you might have an issue - I just size the tanks to handle the peak load, and use controllers that have cooling capability.

Joe


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## wdc1160 (Apr 15, 2008)

master of sparks said:
			
		

> good points NoFo.  A solar array that would supply even a small portion of a winter heating load will turn into an overheating machine in the summer.
> 
> hr



Master,  You bring up a good point.  About year round use.  I thought that I could create a use for some of this ultra hot water.  Where I live it is extremely humid in the summer.  I thought I may be able to use the hot water in conjuntion with a wood drying kiln.  That is what I wanted to do with the extra heat.  I also will have very large storage soon as well.  And, during the summer months will only require 120 -140 degree water.  Essentially I would be able to dry the wood even at night.

As for winter usage (I am only going of anthony D's example)  I figured that some days anthony D's setup would gain 40K but in winter.  His overall system is speced for 100K btu.  We don't know actual numbers as he doesn't log or track except on a per observation basis.  

Is 40K in the dead of winter doable?



Further, some of the literature that you put up said one could run the evac tubes dry, if you don't want hot water from them.  Do you agree with this?


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## BrownianHeatingTech (Apr 15, 2008)

ABGWD4U said:
			
		

> Further, some of the literature that you put up said one could run the evac tubes dry, if you don't want hot water from them.  Do you agree with this?



That's generally considered to be a "very bad idea."

Some tubes have thermal cutoff valves built into them, but intentionally cycling those valves would be a bad plan.

If you really wanted to shut down or reduce the heat output, you could always just build a shutter and clamp it over some or all of the tubes.  That's what we do (albeit with cardboard and zip ties) when we are installing tubes during the day.

Joe


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## wdc1160 (Apr 15, 2008)

I defer to your experience, but why would the literature say  runnem dry if you like

Any idea on what would fail if this approach was taken??  It sounded like a too good to be true situation.


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## Bob Rohr (Apr 15, 2008)

I have heard of some drainback designs using evac tubes. Apricus mentions that at their webste.  Sounds like some incredible thermal shock potential?

 I measured over 400F on the evac tube that I had lying in the sun.  That was some of my concern with the thermal transfer grease.  That is much hotter than and aquastat well in a boiler or indirect tank sees.   Some of the transfer grease manufacturers suggest removing, checking and re-greasing from time to time on high temperature applications.  You need to use the proper type of grease for the application.  I applied some typical off the shelf grease from Johnstone Supply and it turned to rock within minutes at those temperatures.

 hr


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## Bob Rohr (Apr 15, 2008)

master of sparks said:
			
		

> It's not the case of the glass breaking on evac tubes, as you mentioned that shape is very strong.  Their failure is typically loss of vacuum, although hail has been know to break even evac tube glass.



And how does the vacuum fail?  Something has to break for that to happen.

There are different types of evac tubes, but they all have a seal somewhere to keep the vacuum.  It my understanding when an evac tube fogs it has to do with a failed seal, not broken glass shells necessarily.

Some info on various types from www.Apricus.com

Type 1 (Glass-Glass) tubes consists of two glass tubes which are fused together at one end. The inner tube is coated with a selective surface that absorbs solar energy well but inhibits radiative heat loss. The air is withdrawn ("evacuated") from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss. These tubes perform very well in overcast conditions as well as low temperatures. Because the tube is 100% glass, the problem with loss of vacuum due to a broken seal is greatly minimized. Glass-glass solar tubes may be used in a number of different ways, including direct flow, heat pipe, or U pipe configuration. Apricus uses a high efficiency heat pipe and heat transfer fin design to conduct the heat from within the evacuated tube up to the header. For more information about heat pipes, click here.

Type 2 (Glass-Metal) tubes consist of a single glass tube. Inside the tube is a flat or curved aluminium plate which is attached to a copper heat pipe or water flow pipe. The aluminium plate is generally coated with Tinox, or similar selective coating. These type of tubes are very efficient but can have problems relating to loss of vacuum. This is primarily due to the fact that their seal is glass to metal. The heat expansion rates of these two materials. Glass-glass tubes although not quite as efficient glass-metal tubes are generally more reliable and much cheaper.

Type 3 (Glass-glass - water flow path) tubes incorporate a water flow path into the tube itself. The problem with these tubes is that if a tube is ever damaged water will pour from the collector onto the roof and the collector must be "shut-down" until the tube is replaced.


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## BrownianHeatingTech (Apr 16, 2008)

master of sparks said:
			
		

> Some of the transfer grease manufacturers suggest removing, checking and re-greasing from time to time on high temperature applications.  You need to use the proper type of grease for the application.  I applied some typical off the shelf grease from Johnstone Supply and it turned to rock within minutes at those temperatures.



Yeah, you should use the right grease.  Just like you should use the right insulation or the right piping, or the right anything else.  These things (whether evac or flat-plate) work best when installed correctly.



			
				master of sparks said:
			
		

> It my understanding when an evac tube fogs it has to do with a failed seal, not broken glass shells necessarily.



It depends on the tubes.  A number of manufacturers include an oxygen-scavenging chemical (typically barium) within the evacuated chamber, which will fog up if exposed to large quantities of oxygen, thereby alerting you to the vacuum failure.  Of course, the tube is still functional without a vacuum - it just loses some of its efficiency.  Good idea to replace it when it's convenient.

Joe


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## Telco (Apr 16, 2008)

ABGWD4U said:
			
		

> [I thought I may be able to use the hot water in conjuntion with a wood drying kiln.  That is what I wanted to do with the extra heat.  I also will have very large storage soon as well.  And, during the summer months will only require 120 -140 degree water.  Essentially I would be able to dry the wood even at night.



Using solar heated water to dry wood is a great idea.  Eventually I plan to do a solar shed with flat panels making up the southern wall to supply the bulk of my hot water, with a 1000 - 2000 gallon storage facility (I believe in overkill), and planned to use an overhang on the roof to control summer heating.  If the overhang wasn't enough, was thinking about adding a thermostat controlled electric awning to deploy and add more shade when needed.  Using the water to heat up a shed full of wood to dry it for the next winter would be a better use, since it means you can use the entire panel year round rather than having to shade half of it for half the year.  This would also let you use summer heat in the winter, since the dried wood would work better in a wood fired stove.  Excellent!


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## brad068 (Apr 17, 2008)

BrownianHeatingTech said:
			
		

> ABGWD4U said:
> 
> 
> 
> ...



Joe, 
I think I'm interested in the Caleffi iSolar 1 or 2. What is the price tag on these. We just had a grand opening for a Caleffi supplier and this item caught my eye. I acquired a solar system with 4- 4x8 tempered glass panels,trellis,couple finetube exchangers and the two piece fiberglass tank, insulation, all the lumber and 150' of copper tubing all for nothing as long as I removed it. I'm still reading through their literature and they sure have alot of products that I will need. Is this good stuff?


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## BrownianHeatingTech (Apr 17, 2008)

Garnification said:
			
		

> I think I'm interested in the Caleffi iSolar 1 or 2. What is the price tag on these.



Excellent question...

I've only used the Plus and the 3, so those are the only ones I have pricing stored for.  And the 3 in the new catalog has a different part number than the 3 that i have pricing for, so I wouldn't trust that price.

The plus would retail for about $450, at a guess (I don't really have retail numbers for it - just my wholesale pricing).

Joe


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## brad068 (Apr 17, 2008)

Joe, Is that electronic output relay for speed control the "cats meow"? Does it work with all circs within the amp rating?


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## antknee2 (Apr 17, 2008)

BrownianHeatingTech said:
			
		

> ABGWD4U said:
> 
> 
> 
> ...



Thanks for the link on Resol controller , I am very interested upgrading to a controller with more advanced features . Any links on a good reseller with a website ? 
Anthony


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## Bob Rohr (Apr 17, 2008)

The Caleffi I-Solar Plus with 2 variable speed outputs lists for $760.00, 

The I solar 3 with standard output relays (no speed control) has a list of $555.00.  Discounts vary from wholesaler to wholesaler depending on their volume.

The relay is rated at 1 amp.  If you connect a valve or another relay to that output you need to lock it in the 100% mode, bypassing the V/S function.

They show 3 sensors included, in the literature, I'd swear my last one had 4 sensors? 

All the Caleffi controllers include a pre wired power cord which is a nice feature.

 Many of the larger chain HVAC  wholesalers have Caleffi inventory.  You should be able to locate a dealer near you on the website.  If no dealers or reps are in your area, you may be able to buy direct.

 hr


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## antknee2 (Apr 17, 2008)

master of sparks said:
			
		

> The Caleffi I-Solar Plus with 2 variable speed outputs lists for $760.00,
> 
> The I solar 3 with standard output relays (no speed control) has a list of $555.00.  Discounts vary from wholesaler to wholesaler depending on their volume.
> 
> ...



Thank you hr 
Definitely looking forward to a major upgrade on the solar controller and a system that can monitor all aspects of my heating system , which has taken on a life of it own out there in the boiler / pool room . 

https://event.on24.com/eventRegistr...5499F8B23B8D49727BA431A85&sourcepage=register


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## BrownianHeatingTech (Apr 17, 2008)

Garnification said:
			
		

> Joe, Is that electronic output relay for speed control the "cats meow"? Does it work with all circs within the amp rating?



I think it's a "nice idea" - not necessarily the be-all, end-all of solar control.  I use the Plus because of how adaptable it is to a variety of situations, and to future expansion.

For that matter, it can actually control charging of a storage tank using a wood boiler (not that a Garn would need that, but others might).



			
				master of sparks said:
			
		

> The Caleffi I-Solar Plus with 2 variable speed outputs lists for $760.00,
> 
> The I solar 3 with standard output relays (no speed control) has a list of $555.00.  Discounts vary from wholesaler to wholesaler depending on their volume.



Man, they make some money on those when they sell them retail, don't they?



			
				master of sparks said:
			
		

> They show 3 sensors included, in the literature, I'd swear my last one had 4 sensors?



Yeah, mine did, as well.  Two with 1.5m lead wires, and two with 2.5m lead wires.

Rumor has it they will be adding their own pumping station to the mix, soon.  The current pumping station (like the controller) is something they outsource.

And a flat-panel collector, for those who like such things 

Joe


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## Bob Rohr (Apr 17, 2008)

Right out of the box the I-Solar controls will do some data logging.  Operating hours for the various relays can be read.  You can dial in the flow rate as observed from the flow meter and type and % of glycol and get some  energy data in KW/hr.  It will not be as accurate as a btu meter that measures the flow constantly, but it does give you some good ball park ideas of energy transfer.

Some homeowner enjoy watching the hour meter to assure they are getting some solar energy return.

I believe the Resol drainback control will be available soon, possibly a control for PV powered pumps.

Remember today is the last day for the earlybird $49 sign up for Siggy's May 1 9o minute webinar on solar design.  This should be an excellent show for those interested in solar design and installation.   www.pmengineer.com

 hr


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