Record High Temperature for my System

[David]

You can put flow and return inside 15mm Armiflex which saves time and space.

I wouldn't do that, except perhaps over a very short pipe run. I prefer as much of the heat as possible to get to the cylinder.

[O MidKnight]

You can put flow and return inside 15mm Armiflex which saves time and space.

I wouldn't do that, except perhaps over a very short pipe run. I prefer as much of the heat as possible to get to the cylinder.

David Hi.  Flow and return in one pipe? Very interesting and open perhaps to debate. Is there a seperate thread about this topic? - if not I think it deserves one

[Paulh_Boats]

You can put flow and return inside 15mm Armiflex which saves time and space.

I wouldn't do that, except perhaps over a very short pipe run. I prefer as much of the heat as possible to get to the cylinder.

David Hi.  Flow and return in one pipe? Very interesting and open perhaps to debate. Is there a seperate thread about this topic? - if not I think it deserves one

It works fine. I have measured temperature drops across the pipes and there is neglible mixing for the 2m that are combined. My tank got up to 68C yesterday, beat that in February!

If you think about it thermodynamically, a slight mixing will not reduce the net energy into the cylinder. If it did - where does the heat magically dissappear to?  Slight mixing will put a higher temp into the manifold, which gives a higher temp out of the manifold.

Mixing would only be a problem if the heat flux through the pipe was not significantly higher than the heat transferred by air/conduction from one pipe to another. And since it is a closed, insulated system all the heat will eventually be absorbed in the tank, until it is 4C below the manifold.

Installation was significantly easier and tidier in and around the airing cupboard by combining the pipes. Up in the loft they split towards the manifold ends. See here:
http://www.navitron.org.uk/forum/index.php/topic,1426.msg10250.html#msg10250

-Paul

[David]

If you think about it thermodynamically, a slight mixing will not reduce the net energy into the cylinder. If it did - where does the heat magically dissappear to?  Slight mixing will put a higher temp into the manifold, which gives a higher temp out of the manifold.

If the insulation was perfect that is the case. No heat would escape from the insulation.

However, with imperfect insulation the problem will get worse the longer the combined pipe run is. That is why I said I might only do it over a very short pipe run. 2m is a very short pipe run. Of course over a short run there is little saving in cost, though it will make for a neater installation.

[O MidKnight]

My system has 2 x 10mm pipes inside one piece of insulation for over 25 metres. I do think that some of the heat gained is lost on it`s way to the cylinder. It may be absorbed by the return pipe to the flat plate panels and perhaps lost there. On the other hand, on less productive days - the flow and return pipes may be keeping each other warm. So my answer is... I do not know

[dhaslam]

Any idea how much cooler the flat plates are?

[O MidKnight]

cooler than the outlet from the 20 tubes?

No, no idea. Perhaps those stick on thermometers Paul mentioned would be a help there.

[billi]

hello

just a bit bored about allways comparing flat to tubes

the intallation i helped at my parents place installed 10 sqm flat ones   i know for the same price we could have got 15 sqm tubes   but   in the end it was just the choice of the customer   and we or my dad  just liked to have the italian company   that manufactured his woodgasifier his 1250l storragetank and the highest rated flat penal in europe in a small workshop   the two sons about 24 years old did fly over to our place in ireland to advice  nice i think ...........


perhaps he my dad ended up paying more for his setup but beeing conserned or correct he liked the  idea to stay in europe


i donot know how accurate the messurements are from the swiss solar institude  but its a    myths that flatties are not good in winter 


i am getting tubes myself ...  because having a supplier that gives me 3-4 times the amount  of area, but there are other people out therel ooking for mercs..

and were are our friends gone   the helicopter stuard and paul with the biting terrier ?

gone for ever ?

cheers billi

[Ivan]

14th Feb, I've managed 44C at the base of my cylinder today. Not a patch on Paul's temperatures, but that's my fault for having long 15mm piperuns. Looks like it's really 'switched on' for spring. Forecast is poor overcast weather tomorrow. If so, I'll post a more typical temperature for this time of year.

[WyeSolar]

Uncletig,

By chance this morning I saw your reply to my request (20/9/2007) Yes I'm still interested in retro coils for various megaflows got family interested in solar and they all have different size megaflows and it becomes a expensive project to go to a Solar MegaTech so the retro coils would be the way to go! What is the performance like?

Regards

Rob

Hi there Rob,

Performance is excellent when comparing the cost of replacing the cylinder. I would suggest that my two retro coils are about 75% as effective as the proper solar coil.

Important to note that installing retro fit coils will invalidate your Megaflo 25 year warranty!

Also fitting copper coils into a stainless steel cylinder is a real no-no. The steel will corrode the copper. I intend to remove my coils annually for inspection, as I only fitted them last September the inspection won't be for a while.

As to whether your cylinder can accommadate a retro fit coil....if you have the newer HE model then no. This is because the newer immersion ports are incorporated with the cylinders electrics (safety temp sensor etc).

If your still keen to go further, upload a picture of your immersion port(s) and I'll try to help more.

Hope this helps

Mark