evacuated tubes

[Big Al]

I've got a question or two about something i've heard about evacuated tubes but I don't want it to desend into a slagging match like the last one. If it does as the originator of this post i'll ask the mods to close the subject and then leave the site.

Right, question 1.

I've been told that the evacuated tube solar panels from all makers are prone to being smashed by the likes of hailstones ( after all they are only like flurecent tubes) and are not covered by your household insurance policies.

Q2, I was told to stay away from the clear skies grant system as the costs are always more expensive than other systems......

Anyone got any POLITE thoughts???
tia,
Big Al.

[MKG]

Exactly the same thing has been worrying me. So far as I can find out at the moment, the glass used in tube manufacture is particularly strong - less likely to be broken than, say, a skylight window. As I've never heard of a skylight (in the UK) being broken by normal hail, it all sounds OK. But, as I say - this is what I've heard, not ewhat I know.

[Annpan]

Are the evacuated tubes all separate, so if the worst does happen (and lets hope MKG is right about their strength) you would just have to replace the broken one... perhaps a small cost (though I have no idea)

I have also heard of the clear skies being a bit of a sham... the few registered companies can charge more for the job because of all the free advertising they get, and the fact that you get a third off, makes the saving look bigger IYKWIM. I suppose you could contact a few companies (with and without clear skies approval) and try to compare.




ps. thanks for the help with the bike in the chat room BTW Big Al

[Wombat]

We have had flat plate solar collectors on the roof for 25 years, through hail storms with no worriies. I would have thought the curved glass of the tubes would be inherently stronger......

Nev

[MKG]

Are the evacuated tubes all separate, so if the worst does happen (and lets hope MKG is right about their strength) you would just have to replace the broken one... perhaps a small cost (though I have no idea)

Wouldn't you know it? This apparently obvious question isn't answered by any manufacturer or supplier I've found so far. I'll keep looking - surely no-one sane would produce a panel with non-replaceable tubes?


EDIT: But then I found it. Yes, you can easily replace individual tubes (assuming you can get to where the tubes are). All you have to do is find a source of replacement tubes.

And I found this ...

http://www.enviro-friendly.com/Endless- ... Manual.pdf

... obviously by a system manufacturer, but it has lots of informational goodies in it!!!!

[Odsox]

That's an interesting link MKG and one that I will read more thoroughly when I have time.

Two things caught my attention ... they supply a stainless steel cylinder (as per my other thread)
The system apparently runs at 5.3 bar or 78 psi which to my mind is pretty high pressure.

The other thing is there is no mention of a secondary coil indirect cylinder just direct.
There is certainly more to this solar heating than I thought ... I think I am even more confused now.

[MKG]

Just have a google around for evacuated tubes. It soon becomes obvious that they can be used in any system, in any configuration. They're most efficient in a direct system (but you can say that about any heating method) and I suspect that installers prefer stainless steel tanks and pressurised systems becasue then they don't need to put in a separate cold-water tank. But in the end, you can install evacuated tubes as part of any system as long as you can physically connect them in.

[Big Al]

I'm a lot more clearer now on this subject.

I'm not going for a direct system for a number of reasons. Mainly the fact that if the water is not heated to above 65Deg C which it won't be in the winter then legionella spores can bread and as you are using the water in the direct system you are at risk. With an indirect system you don't need an anual insoection and you can also loop onto the system other heat sources such as multi fuel and the combi boiler if need be. Also evacuated tubes are extremely strong and don't explode as some people tend to think. If you chuck stones at them then they will break but all tubes are seperate and easily swapped if in the indirect system as the fluid that is heated ( many use glycol) is in the metal part of the tubes and not the glass. AMK-Solac is a swiss system and the one i like the look of. Visselman ( or something like that ) also make a very good system but I've not looked at that set up yet. If you look at purchasing the solac system then go for the newer version of DR over the old version of opc10 or opc15 apnels. These are more efficient as the parabolic reflector on the opc set up corrodes after about 4 - 6 weeks and pecomes pitted so the light is not reflected off as readilly thus after about 6 weeks the efficiency drops by around 15%. This is from the company website.

I'm also going for a Gledhill Torrent RE tank. Probably 210 or 350 ltrs, not decided yet.

I'm also going to purchsse the bits myself and employ someone to install and commision it. Main reason is that i've found out that roughly 70% of the cost of instillation by the "big boys" in the industry is down as "installation costs" and I've got two fantastic plumbers who are fully certificated for all the work I need them to do.

Well at least that's what I propose to do at the moment......
HTH

Big al

[Big Al]

Some interesting sites....


http://www.gledhill.net/building-produc ... ar-dia.pdf

http://www.gasapplianceguide.co.uk/torrent_indirect.htm

http://www.gledhill.net/building-products/bp-index.htm

http://www.greensystemsuk.com/solar_hot_water.php