Types of evac solar tubes

Unknown

from the Viessman guys. I think I know whos been giving vac tubes a bad rap.
TONY

Unknown

If we are going to help each other

Lets start by giving each other more definitive aswers. Here is a list I copied of the 3 different types of vac tubes. If you have a failure please mention the brand,type, and system type. This way we can really learn something here.

TONY

Evacuated Tube solar water heaters are made up of rows of parallel, glass tubes. There are several types of evacuated tubes (sometimes also referred to as Solar Tubes).

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 The air is withdrawn ("evacuated") from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss.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. SunSurf uses a high efficiency heat pipe and heat transfer fin design to conduct the heat from within the evacuated tube up to the header.

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

brendan_5

Tony
In type 1 discription you failed to mention the heatpipe to glass seal,I believe it is a metal/rubber/glass
seal. How will that seal withstand contaminents in time?

just wondering Brendan.

rene_4

Brendan
The heat pipe doesn't touch the glass at all. Look up the web site for APRICUS evac tubes. They have several pictures showing how the system works.

Rene

brendan_5

Rene
I agree it doesn't touch the glass but it is sealed at the manifold end via a rubber plug. How will this rubber seal handle extreme temps?

Brendan

UNUSEXFER

Apricus

That rubber plug is a weather seal only. The heat pipe & evac tube are completely separate. The tube is a glass "thermos" & the heat pipe is suspended inside on the absorber, & is connected to the manifold to transfer heat. Heat transfer paste mates the manifold & heat pipe.

Unknown

High temp silicon

is what the seals are made of.They seat on the manifold then expand when the tube is pushed in. I use honeywell heat tranfer grease on the heat pipe and silicon grease on the seal before I push it in. Almost impossible without it.
TONY

rene_4

I put a slight coating of Never-Sieze on the condenser and used a Household liquid detergent for the rubber grommet. Works great!!!
Rene

michael_34

Tony this is I posted back on July 29th

I just went on a service call for these solar maxx tubes. This guy has a 75 tube system and was getting no heat. He thought he had air in the system. I got there and looked at the flow meter, no air. Went up to the array and the hot pipe going to the Boiler room was cold. I decided to pull an evacuated tube out and low and behold! There was no connection between the tube and the manifold. The inside guts of the tube slide so far down that it lost it's connection. Very bad design by solmaxx. The customer and I pulled all the tubes off and pulled the guts out and reset the tubes with a good connection. That being said, the customer will have to check those at least once a year. Gravity will just keep pulling them down. The customer has had these for one year now. He says that you can never get a hold anyone. Now that there all reset (tubes) the system is working fine. I just would not want to have a lot of maintenance for a system. Hope that helps. Michael
Dec 11th. Tony
I have seen also Sunda's lose their vacuums (some from over heating others I don't have a clue). I install both Tony (flat plates and tubes). I prefer flat plates for these reasons.
!. warranties are longer
2.They are made here in the states (the ones I use)
3. I have not seen any concrete data proving that evacuated tubes perform better in cloudy cold conditions.
4. I believe flat plates are more durable (my opinion)
5. Tubes do not shade snow.
I hope this helps in your quest for info.
I am not against tubes, I don't care which get installed, as long they are and done well.
peace and good luck

Ron Huber_2

The Tubes

Speak for themselves Tony. Regardless of brand they are all having problems. My own Viessmann tube systems have had some failures, but a local Apricus outfit has had LOTS of tube failures, from bad tubes right out of the box to ones that fail in a short period of time, they have been installing for about three years and I think that is the warranty period for most tubes, Viessmann at least has a 10 year warranty. You do not here anything about problems with flat plates, and if you want to stay in business you better not spend a lot of your time on non compensated warranty work. How long is the warranty on your tubes? Tubes are not the "New" technology that everybody is getting excited about, they are just being marketed by companies that can get distributorships for next to nothing and have very little support. I think even Viessmann has backed off some from the tubes.

Paul Pollets

Evacuated tubes

I'm a 'Viessmann Guy'and use their Vitosol 300 tubes. My oldest system is 8 years old and no tube failures. I have received tubes broken in shipping. They were replaced by the wholesaler within 3 working days.


I'd be very careful about the evacuated tubes coming from China. It is already known that they seem to have a short vaccum life. The glass is also different from the Viessmann tubes (or Thermomax Mazzdon tubes). Undoubtedly what costs less may not be the best value.

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hot_rod

try polling

plumbers or installer, at least 40 years of age That do service work on solar. Look for contractors that don't "have a dog in the hunt" with regards to sales or marketing of one particular brand or alliance.

Ring up 10 of the evac tube manufacturers and ask about ther warranty numbers.

How many tube manufactuers or suppliers have you found with a 30, 20 or even 10 year record in the US?

I don't question that tubes work, and work better in some conditions. I just wonder that dual vacumn technology is really needed to do such a simple task.

Who takes the hit for the warranty and non performing issues in a race to produce and sell the lowest possible priced evac tube?

We have very solid, 30 year track records of flat panel performance and reliability in this country. Longer if you consider Clarences Kemps "Climax"and William Baileys "Day and Night" 1800 and 1908 built collectors

hr

hr

Paul Pollets

Dog in the Hunt

Since Caleffi now sells a flat panel, I presume you have a "dog in the hunt." I certainly agree that flat panels work fine and have a track record. They will also become a commodity, in fact maybe they are already.

I've installed well over 300 flat panel installations in the 80's, and some are still functioning. I like the evacuated tube technology, especially for higher temp commercial DHW systems.. (if there's no snow load)but each system is different. I do prefer quality components. They result in less service calls. And since the contractor usually takes the hit for "warranty issues", as you mentioned, I'm interested to see what service issues arise with the new wave solar.

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hot_rod

my new job

allows me to be in front of hundreds of contractors, 50 this week, that have many years of solar experience. I merely ask their experiences.

This week I met long time installers, all gray haired with Heliodyne, Renyolds, Rovan, and a handfull I had never heard of, experience. Most were Sunspool experienced, also as that was a common package in this area.

Certainly I have a dog in the hunt, and may have two dogs in that hunt, soon. The folks attending my seminars don't necessarily, and I am very careful to explain the pros and cons of both types of systems and let the installer, dealer decide.

We can define and defend output and performance differences with data and real life installs. It the lifespan issues with the vacumn dependant systems I wonder, aloud, about.

Heliodyne, now owned by a multi national solar company, just releases a paper on their opinion about panels vs tubes. Well presented and from many years of experience also.

As you know many contractors are fairly opinionated and more than willing to share their expieriences when asked, I just pass along what I hear.

hr

michael_34

HR / Tony

When did Heliodyne get bought out and by whom? I agree we should report experiences not opinions when it comes to this debate (all debates).
Tony,
What is your input from the responses?

hot_rod

Heliodyne is now

part of the VRK group. Maybe 2 years now? VRK 15,000 employees in 40 countries, solar, windows, etc. according to their website info.

hr

michael_34

How about bubbling springs? : )

Mark Custis

I want to know

more about the PV you guys do.

I am getting three leads a week here in Cleveland and letting the go away.

hot_rod

BS made in Wisconsin

still around. privately held, last I heard. Perhaps as many a 250 or more companies built and offered solar components in the 80's. only a handfl held on to this current "solar age" AET, Heliodyne, SunEarth. Goldline controls, although i remember them being broght up a while back. i have old solar info from Lennox, Copper Cricket, Grumman, a handful of others.
GE, Corning, Phillips, Sanyo all made evac tubes back in the day.

scott markle_2

I'm interested in the type 3 design. The only collector I know of with this design is made by Schott. I really like this design but it's not available in N.A

I also like the idea of a solar glass product deigned and manufactured by a glass company.

Thanks for laying out the design types.

http://www.schott.com/uk/english/download/solar_thermal_rd319.pdf?PHPSESSID=91

Unknown

Listening and Learning

Went to a Sun Maxx solar school yesterday for installers. There were a few hydronics men there out of about 80.
People from all walks of life trying to get in on the promise of solar. Lots of talk about the typical solar stuff.. angles, latitude, shading but very little on those little things that professionals take for granted... how much air in a expansion tank, how much pressure in a system, the list goes on and on. I mean most people left there and still didnt have a clear image of a closed loop.
Its obvious from the manufacturers point, to much to fast. Not enough skilled mechanics or speakers, Solar systems actually require more time to learn because you have to first understand the system your going to be tying into. The highlight of the day was the thermosyphon tube unit with the 40 gallon tank on top of it, there are no heatpipes in the tubes, they are filled with water/glycol as is the tank, domestic water runs through a coil and the whole thing sits on your roof. mmmm sounds great for down south, So I ask, why the glycol... so it doesnt freeze... so what about the domestic water going in and out? I was givin a long talk about how to run your pipe and insulate them together in a counterflow fashion much like a penguins blood circulates, I interupted and explained that a penguin was a mammal and generated it own heat. Ive have been crawling into godforsaken##.%HOLES sweating frozen pipes since I was 16. I know what pipes will freeze and what pipe wont. Then the conversation went on to the actual contruction of the tubes and manifolds which they had there opened up for us to inspect I was impressed, sunmaxx equipment is very nice and now has a 10 year warranty on all tubes and manifolds, all tube units are SCRR rated and their flat panel is already submitted. The tube units come with a really nice adjustable tilt frame but as of yet the flat panels have no frame mount but they said they are working on it.
All in All it was ok. What they need to do is hire someone like Dan not only to teach the schools but to set up the all the logistic that go with it( they had the school in the Warwick hotel right in the middle of Philadelphia, I had to pay 50 bucks for them just to valet park my workvan).
For now I am staying with Sunmaxx, I like their equipment and it is one of the few tubes that can be used with drainback. But Like Hot Rod compared this too. A dog in the hunt. When a hunting dog wavers you shoot it and get another dog.
TONY

Unknown

I brought this up

I did a google searCh and found that sunmaxx and solmaxx are diffrent companys, at least it appears that way. But anyway the fact is that yes the heat pipe is shorter than the tube in the sunmax and is held there by friction from the absorber plates. I pushed on that tube till the point I thought the tube was going to break and I couldnt move it.
Still they want you to pull the heatpipe out six inches or so and then coat it with the tranfer grease and insert it into the well first, then slide the glass tube up and through the silicon seal. It does take alot of force to push the glass tube through the silicon seal and if the heat pipe bulb wasnt alligned you could push it down.
Rene said she use liquid soap to lubricate these seals, I tried that first myself but in the hot sun the soap was drying up before I could get it in the seal. I then switched to silicon lubricating grease and they slid in really nice.
TONY

michael_34

Tony and Rene

Well keep me posted on if you have any problems like I described (or anything else and I truly hope you don't). I believe we are speaking of the same tubes that are through Silicon Solar.
Any information we can exchange is good for us all. That way the solar thermal field will be a solid well educated one.
Thanks for your input.
Good luck and happy holidays.
Michael

rt_2

Tony,
Me being a homeowner, I was able to wait for a cloudy day to install mine so the liquid soap worked well. Besides, I would want to handle the condensor ends of the heat pipes on a sunny day. There is no way my SUNMAX heat pipes would ever slide down by gravity. Mine came disassembled. I had all I could do to install the heat pipe inside the absorber plates, as you call them, then to install that assembly into the glass tube, I too was afraid to break one. The only problemn I had was that the condensor bulb had to be fitted to each hole in the manifold. I had to use a pneumatic tool with a sanding attachment to open up the holes maybe 0.0005" or so. Just enough so there was a little drag when inserting it. I did this while the manifold was in my garage. I then marked each one for their location. Without doing that, I would have NEVER been able to install them. That's their only downfall.

Rene