Broken evac tube.

rt_2

I checked out my solar system only to find one of my evac tubes had broken. It was the bottom 6 inches. I removed it and found that the aluminum heat sink, which raps around the heat pipe was coroded a little at the bottom end and I was wondering why!!!!. Upon further investigation I found that the heat pipe had a small split about 1 inch from the bottom end. I'm now thinking that possibly when the heat pipe split, the fluid is what corroded the aluminum. Then with no heat inside that evac tube, possibly condensation built up and collected at the bottom. After enough water had collected at the bottom, it froze and the glass broke. That condensation could have also coroded the aluminum. I have no idea when the pipe split. It could have been months ago. Has anyone ever experienced anything like this?. What would have caused the heat pipe to split and loose all it's liquid. I  thought there was suppose to be a mixture of antifreeze inside the heat pipe. Any comments out there? The system was manufactured by SUNRAIN.  Any idea where I can purchase a new heat pipe and glass tube? The company I purchased the system from up here in New Hampshire is no longer in business.  Thanks.

Rene

hot_rod

Sun Rain

seems to be a large company in China, did you try contacting them directly at their webpage? http://en.sunrain.com/



Is it the local dealer that shut down or the manufacturer?



It sounds like a heat pipe style tube. Generally they have a water/ methanol mix or some other antifreeze blend. Perhaps another brand of tube would fit into your header.



There has been quite an influx of evac tubes arriving in the US from China and it is hard to determine the quality of them without a listing and inspection procedure. An evac tube type of collector is a bit more complex than a flat plate style.



I would guess some of these companies will leave the market if the numbers do not work out for them, the residential solar thermal market is a bit soft right now.



hr

rt_2

SunRain

Thanks Hot rod,

The dealer I purchased it from went belly up. He did tell me that Silicon Solar out of New York should be able to get me anything I want. I'm waiting for a call back from them. Apparently SUNMAX Solar Tubes are the same as SUNRAIN. I wouldn't be surprized if they by them from SUNRAIN. SUNRAIN has been in business for 12 years and employ 1000 people. Sounds like a big company. 

Kevin_in_Denver_2

Silicon Solar/SunMaxx

I've dealt with them and have gotten great service. Their website also has a customer service email address that has worked great for me.



Order a couple of extra heat pipes and use one for a test:



1. Measure the OD of the lower tip of the tube (the small end) with a micrometer.

2. coil it up enough to fit in your freezer, make sure any liquid inside will be in the small end.

3. Freeze it overnite.

4. See if the tip has expanded after freezing.



I heard a rumor that it was 100% water in the heat pipe. If the glass tube loses its vacuum then the heat pipe could freeze overnight. After enough nights, the copper would eventually split and the water would leak out.



To check for failures in any other tubes, just feel them on a sunny day. A slightly warm tube means either the vacuum has failed or the heat pipe has failed. I don't know what causes a heat pipe to fail if it doesn't have a split, but I've seen them in my Apricus panel. A failed vacuum tube would probably fog up after a while.

rt_2

evac tube

Thanks Kevin.

 I thought all this time there was something in the water to keep it from freezing. I hope it's not just water. It gets awfully cold at times up here in New hampshire. I did contact Silicon Solar and ordered 3 heat pipes. They're real cheap.

 I just may try your expirement and I will try to see if there are any other tubes which aren't working using your idea. I also thought that it the glass tube lost it's vacuum, the pipe would not stay clear.

rt

Kevin_in_Denver_2

Update

I talked to another engineer who said that those heat pipes can lose their vacuum. Diffusion of gases thru the copper and/or the brazed joint is the most likely reason. A heat pipe without a its vacuum won't work correctly.



Since the replacements are so cheap, I could get one and cut it to harvest the fluid and see if it smells of alcohol or glycol, and measure the amount.



I also heard that the amount of fluid was so small that even if it froze, it wouldn't split the pipe. Your failed tube might have been originally filled with too much fluid.



Or it didn't have enough alcohol. Since the temperatures get pretty hot, a small leak in the heat pipe could cause the alcohol to evaporate long before the water, then freezing could split the pipe.



During my testing last year, I was able to break an Apricus glass tube by thermal shock. This would only happen in a drainback system where the pump kicks on during a dry stagnation event.

hot_rod

That is my concern

with heat pipe evac tubes, how do you know if the fluid has an adequate vacuum pulled on it? as I understand it the vacuum allows the fluid to boil at 100- 110F degrees. Without the vacuum you have a rolled up flat plate collector.



I have heard of under performing tube arrays I suspected vacuun-less heat pipes could be the problem? With heat pipe style tubes you need to maintain the vacuum in the heat pipe and the glass, in every single tube.



Until recently manufacturers were only providing a 10 year or less warranty on some brands. I wonder if the design improved or just the wording on the sales sheet.



hr

rt_2

heat pipe

I understand that the fluid boils at 86 degrees went it's in a vacuum.



RT

ABSolar

Anyone seen my vacuum?

I thought (at least w/ the Sunmaxx tubes) that you can simply identify lost vacuum w/ the barium "getter" that changes color from silver to oxidized white color (I've seen them and it's quite obvious that one of the tubes looks different in the collector)

rt_2

TO ABSolar

You are right. The tube is suppose to change color when the vacuum is gone. I talked to the guy I purchased the system from tonight and he said the SUNRAIN SOLAR out of china told him that there is a small amount of alcohol in the fluid. This not only keeps the water from freezing, it also lowers the boiling point of the fluid. Silicon Solar also told me that they buy there systems fron SUNRAIN. It may have been just a manufactures defect in the heat tube when it was extruded which may have caused it to split. Like someone said earlier, the alcohol may have evapoprated from the water then the water may have froze causing the split. Who knows!!!. I received 3 new heat pipes fron Silicon Solar today. Now I'm just waiting for the snow to melt off my roof so I can get up there and install the new evac tube and the new heat pipe. There's about 18 inches of snow up there. Spring is coming but not fast enough for me.



Rene

rt_2

t

rt_2

To Kevin in Denver

Kevin,

I changed out my broken evac tube yesterday with a new tube and a new heat pipe. While I was up on the roof, I checked a few of the tubes to see if any were warm loike you recommended. About half of them was just a touch warm as compared to the other half. Maybe a couple of degrees that all. They haven't changed color so I know they haven't lost their vacumm. If a heat pipe lost it's vacumm, how would that make the glass get a little warmer than all the other tubes?

RT

Kevin_in_Denver_2

Get a $30 IR point & shoot thermometer

You can find it at the local auto parts store.  Extremely useful for troubleshooting, etc.



It works great on any glass or painted surface and water, but not on shiny copper or galvanized pipes .



An evacuated tube has a high vacuum between the two walls of glass.   If the vacuum fails, the shiny silver surface at the bottom of the tube goes smoky white/clear.   Of course, a failed tube will be hotter.  Note this color change is only at the very bottom.   You might even have to unscrew the cap to see it.



There is also a partial vacuum inside the hermetically sealed copper heat pipe.   If that vacuum is lost, the heat pipe just doesn't work, and that tube will be roughly 8-20 degrees hotter than a functional tube at full sun.   It's hotter because the heat pipe isn't sucking the heat out of it and delivering it to the header.  If the collector is stagnating, you might not see much of a temperature difference.



I really wouldn't expect 50% bad tubes on a SunMaxx collector under 10 years old, but bad batches can happen.

rt_2

To Kevin in Denver

Kevin,

If I get a chance one day this week, I'll pull a couple of the tubes and check out the heat pipes. I'll let you know what I find. Thanks for your input

RT

Fortunat

bad tubes and heat pipes

As others have said, a tube which loses its vacuum is easy to spot because it changes color and often also has condensation inside.



A bad heat pipe is harder to see. In the summer and in bright sun I find I can tell the difference by touching the glass (the bad heat pipes don't move heat to the manifold so the tubes get hotter), but in the winter the difference is really hard to notice.



I didn't have much luck with an IR thermometer, but an (expensive) IR camera makes it pretty obvious, even from the ground.



The two attached images are of the collector at one of our shops which I deliberately filled with a couple bad heat pipes for the sake of this test. As you can see from the scale, this was a cold winter day. Once you get the IR camera settings right, the bad ones stand out. Actually the really bright one that shows up in the middle of the array even on the dark photo is a bad tube, which we also stuck in there for this test. So it looks to me like (at least in this condition) a bad tube is a bit warmer than a bad heat pipe.



The best way to definitively test a heat pipe is to stick the tip (18 inches or so) into some warm water (140 degrees). If the condenser bulb gets too hot to touch, the heat pipe is working. If not...then not.



~Fortunat

www.revisionenergy.com

 

ABSolar

Infrared Imagination...

Hey Fortunat'

That was WAY COOL w/ those thermal images!  I can't wait till prices drop on those tools!

rt_2

To Kevin in Denver and Fortunate

First I want to thank both of you for some good information. Now for the bad news. I went outside today and pulled 2 of my tubes that was just a trace warmer than some of the others. Guess what, both had heat pipes which were split at the bottom. I counted all the one's that were  a little warm and I've got a total of 24 out of 50 that are bad. Not good. I called the person I purchased the units from and he knew that something was wrong with his system because over this winter, he was only getting about 40%  of hot water from what he use to get. He went out and counted his which were warm. Out of 175 tubes, he has 130 which appear to be bad. He is no longer in business now because SUNMAX or SILICON Solar took over the entire distributorship in the US for SUNRAIN which is out of CHINA. He sold me (2)   25 tube collectors. He also sold another 41 to other people in this area. Now we don't know what to do. He's going to call SUNMAX tomorrow and see if they can do anything for us and also to let them know that they have a very serious problem. I wouldn't buy any collectors from SUNMAX or SILICON Solar until this issue get's resolved. Sunrain advertises on their Website that their units are compatible in cold climates. WRONG!!!!! Anyone have any ideas how we can handle this?

RT

Fortunat

warranty issues

like anything else, the warranty is only as good as the company behind it.



 In the last six weeks I've been dealing with warranty issues related to a chinese evacuated tube, an irish made evacuated tube, an Isreali made flat plate and a US made flat plate (as well as a whole bunch of Canadian/US made PV inverters and an Italian pex tubing manifold).



The above is not because we install junk; we do not. But it is because we do a high volume of work and have several thousand systems installed. Inevitably a handful will experience difficulty.  In every one of the cases above, we're committed to doing right by our customers and in turn, the manufacturer and distributor are doing right by us and are standing behind the product and honoring their warranty obligation.



So if the manufacturer of your collector still exists, and if they have a US distributor, that is where I'd start. Call the distributor and ask them about the process for making a warranty claim. If they want to stay in business, they'll do the right thing.



Good luck,



~Fortunat

www.revisionenergy.com

rt_2

Things are looking up!!!!

I had been communicating directly with SUNRAIN in China via E-Mail when I  first found the problem back in January.  At that time, they said they would send me a new heat pipe but the cost for the pipe plus shipping was out of this world so I ended up going to SUNMAX/SILICON Solar.

I continued my conversation with SUNRAIN via E-Mail last night and they replied this morning.  They started out by saying that it was not unusual to have to change out all the heat pipes every 3 to 5 years the way they were designed back then. I'l bet you dealers weren't aware of that!!! Now, they're saying that 2 years ago, they upgraded their heat pipes with a different antifreeze solution which would lower the freezing point and hopefully  they should last longer. He said that they should be good for -25 to -35 degrees Celcius. I conducted a test on one of my new heat pipes las night. I coiled it up as small as I could without kinking it and put it in my freezer making sure all the liquid was at the bottom. I just took it out and measured the OD at the bottom and there was no swelling/expansion at all.

 Now the good thing. SUNRAIN said they would replace my damaged heat pipes at no cost to me. I sent them my address so now we'll see if they follow through with it. Things are looking up.

I fell bad for anyone who had a system installed more than two years ago and they live in a very cold climate in the winter. They may be surprised if they inspected their heat pipes.

RT

Kevin_in_Denver_2

No swelling here

I also froze a new heat pipe and only saw about .002" of swelling. I doubt that .002" is beyond the elastic limit, but I'll cycle it a few times.



Boy, I hate those "unforseen" effects.



What was the manufacture date on your original equipment?

rt_2

To Kevin in Denver

I purchased the collectors in June of 08 and got up it up and running around September of 08. So it's less than 3 years old. I'm hoping that they fixed the problem with heat pipes 2 years ago. Maybe that was an  issue back then and that forced them to make changes. I get the feeling that they've been aware of this problem for some time now because he didn't seen hesitant to replace most of my heat pipes. You're right about the expansion. .002" is nothing. Thanks for your input and suggestions.

RT

Kevin_in_Denver_2

Heat pipe mystery

Curiosity got the best of me so I drilled a hole in a spare heat pipe to get the liquid out. There was only a tiny amount that came out, less than 2 milliliters. I couldn't smell any alcohol at all, and it seems to me that it's 100% water. In the water was also half a milliliter of solid particles that look like copper. The particles range from .005" to .013" in diameter.

rt_2

Kevin,

Was that heat pipe manufactured by SUNRAIN out of China?  If you got it from SUNMAX/SILICON Solar here in the us then the chances are it was made by SUNRAIN.

I learnt a valuable lesson. When I installed my tubes back 3 years ago, in order to help sliding it into the rubber grommet at the top, I lubricated the rubber with liquid dish detergent. It worked great for the install. I now found out that that was the wrong thing to do. Over time, the liquid dries out and now it acks like a brake band making it very dificult to remove the tube. I had to spray penetrating oil around the rubber grommet . That help a little but not much because it wouldn't flow uphill. What do you pros use if anything at all to help with the installation and would help during removal later on? I thought about using a high temp grease like you would use in automobile wheel bearings. I don't believe it would have any effect on the rubber because wheel bearings also have a grease seal  and it's has rubber.

hot_rod

Nice

which model Filr do you use?j

rt_2

Anyone have an idea?

What do most installers use to lubricate the glass tube (if anything at all) where it passes through the rubber grommet at the top of the manifold in order to make it easier to remove a glass  tube later on? I used liquid detergent and I've found that it worked great in the installation but after it dries out, it acts like a brake ban. Any ideas would be appreciated. Thanks ahead of time.

RT

Kevin_in_Denver_2

pliers

I had to pry the grommet out a little, then grab it with needle nose pliers. Not that bad, really. But yeah, forget about twisting the tube out by hand before that.

rt_2

Thanks Kevin,

I removed all the pipes today that were just a liitle warmer than the others and everyone of them the heat pipes were split from freezing. I like your idea about trying to remove the grommet first with a pair of needle nose pliers. I'll try that the next time. I received an E-Mail from SUNRAIN in China today and they said they would be shipping out 50 new heat pipes hopefully today.

Kevin_in_Denver_2

good news

Sounds like you got a bad lot.



It sounds to me like they were overfilled and didn't have any antifreeze in them. Did the factory explain what happened?

Unknown

im dumb & pretty2

but cant u just do a piece of pipe in place of the tube?

rt_2

Kevin

All they said was that 2 years ago, they changed the formula for the liquid which would allow it to be used in colder climates. I've got the feeling that there was anything in the fluid to keep it from freezing. They shipped the replacement heat pipes yesterday and asked me to ship the bad ones back to them so they could analize them.

RT

rt_2

Pook

It's not just a matter of changing the pipe. It's a piece of copper tubing a little smaller than 1/4". At the top is a condensing bulb which fits snugly into a socket in the main header at the top of the collector and it's plated with NI. It's around i inch diameter. There is a small amount of liquid inside the pipe and it has some type (supposedly antifreeze) which keeps it from freezing. Also there is a slight vacuum in the pipe. This allows the liquid to boil at a much lower temperature. I'm told it boils at 86 degrees F.

RT

Unknown

thanx 4 the info

& good luck

rt_2

New Heat Pipes. Up and running again!!!!!!

I got 50 brand new heat pipes from SUNRAIN out of China the other day. There is a little difference in the way the heat pipes are manufactured compared to the old heat pipes. The bottom end more or less comes to a point instead of the end being crimped to hold the fluid in. Maybe this was where their issues came from. I installed the new heat pipes and what a difference that made. In one day of heating, my 80 gallon storage tank went from about 100 F to 157 F. They sent me enough to replace all the heat pipes but I only replaced the ones which failed so far. I'll just check on them every so often to see if anymore fail. I checked on sending the old pipes back to them. If I went with FEDEX, it was going to cost about $180.00. So I E-Mailed SUNRAIN and said it was not going to happen and if they wanted these pipes bad enough, they would have to pay the shipping. They replied back and  said to simply keep the bad pipes. I'll sell them to the junk man for the copper.

RT 

Kevin_in_Denver_2

Heat pipe fluid mystery cont'd

After I drained a heat pipe, I put the fluid in the freezer. It freezes solid.

So the small amount of fluid is really the freeze protection method.



The vapor pressure of the fluid is higher than pure water, though, so there probably is a little alcohol. Just not enough to prevent freezing at 0 deg. F. There's more condensation on the sides of the storage bottle I have it in, than in similar bottle with only water.

rt_2

Kevin

Interesting. I wonder what the new formula contains!!!!!!

RT

rt_2

Kevin in Denver

I E-Mailed my contact @ SUNRAIN in China and I asked him if he could tell me what they use for the liquid in their heat pipes. I really didn't believe that he would tell me but he did reply in two different E-Mails. Please excuse his broken english but in the first E-Mail, he said this:

I am sorry for can not tell you what fill in the heat pipe, it is our company technical secret. we test the whole heat pipe in -13F and the heat pipe is no problem. So I hope you do not worried for it any more.



In the next E-Mail he said this:



I have contact with our technician, the liquid in heat pipe is special liquid, though it froze in 30F, but the structure for the solid without destroy for the heat pipe, the solid is different with common ice. so please do not worried on it.

 

I think he's trying to say that the composition of the liquid, even though it freezes @ 30 F, it doesn't expand like regular ice. Is that what you get out of it Kevin or is he saying something else?

RT

Kevin_in_Denver_2

doubt it

I think he believes that this fluid doesn't expand on freezing. Since I'm sure that It's mostly water, I don't. But since I found just a few drops, and surface tension draws water up the sides of the pipe, there isn't any room for an ice plug. But that's way too hard to explain in Chinglish.

Fortunat

copper powder

I think Kevin is basically right. I believe the 'antifreeze' in these heat pipes is often just some fine copper powder or something similar. I don't know exactly how it works, but I don't think it actually prevents freezing, it just (in theory) prevents damage from freezing.



It sounds like Sunrain (and other chinese manufacturers) have been doing some tinkering to get the formula just right for the US's northern climates. Actually I think a lot of the Chinese tube manufacturers buy both the tubes and heat pipes from others and just build manifolds and frames so many different brands of collector could be using heat pipes coming from the same factory.



Hope the new heat pipes solve the problem.



~fortunat

rt_2

Fortunate

I think you may have hit the nail on the head as far as copper in the water, I remember Kevin saying in an earlier post that when he drilled a hole in the pipe, he found water and some copper particles. Maybe that's their formula.

RT

Kevin_in_Denver_2

A little more info and a theory

Here's a link to Sun Rain's description of their heat pipes:

http://en.sunrain.com/html/solar_collector_heat_pipe.html



My new theory is that the copper particles help ensure that the tip freezes first. If the water freezes tip first, expansion can occur without damage.



Normally, however, water in a container freezes from the top down. That's mainly because ice floats. If ice forms at the top, then it captures the water below. When that water freezes, it ruptures the pipe.



Overfilling would explain this failure mode.

Kevin_in_Denver_2

Copper Powder "antifreeze"

A poster at a different forum has stated that the copper powder is the antifreeze, based on an email from the manufacturer.



See message #78

http://www.solarpaneltalk.com/showthread.php?4096-Bad-experience-with-evacuated-tubes/page8