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Garage_Hermit

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Reply with quote  #41 
Thank you for the feedback, gents !

@Paulstef  Even if I only get *one* freezing night in a year, that is enough to wreck an expensive system !
(Hate to draw parallels, but think of the Challenger disaster...).
The inside of the facade will certainly get cold - even if there is no actual wind-chill factor, it is still soaking in ambient cold air overnight...
So on a minus 4°C night, the inside of the facade (therefore the copper manifold...) is at minus four Celsius = freezing and broken pipes or at least leaking joints...
I can't see what type of frost protection U mean, other than steam tracing or electric elements - kind of defeats the object (it would be better in that case to just run the circ backwards at night, and use the *tank* to *warm* the collector...) (WOW, in fact, mebbe U just gave me a great idea !  run the system overnight any time there is a risk of freezing!) (since the energy is free, why not use some of it for a useful purpose...).
I obviously need to think about this a bit more [rolleyes]  (well, that 's why I post !!) so thanks, very glad of the help !!)

P.S. Yes, U R right, I suppose the house *does* leak heat out through the wall, towards the collector. (Because the facade wall has no EWI like the rest of the house)(however, the facade IS stuffed with FG insulation, but I am actually (progressively...) ripping it out...).  I guess the definitive thing to do, is do a temperature trial lasting all winter, and compare the outside ambient, with the collector internals, and see how it actually works... I have to admit, to not yet having done this imortant / essential phase...

@Willie  Must admit, U have got me thinking with this one !  "folded riser collector" - I took a pencil and tried to draw this, but had to give up !  Please feel free to enlighten me !

Many thanks again for the feedback,

G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...

stmbtwle

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Reply with quote  #42 
Something like this?  Not sure about the position of the vacuum breaker, or if it's even necessary.

[image]

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #43 
Wow, Impressive thinking, many thanks !
MUCH better than my attempt !

Like yourself, I suspect that the vaccum-breaker might not be necessary - during drainback, the system should pull its own air, up though the HOT line...

(Which is open to atmosphere in any case, because the tank is "open air").

Thanks again, Willie !

G_H


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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
stmbtwle

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Reply with quote  #44 
I wasn't sure, just figured it was better to be safe than sorry.  Comments, anyone?
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Willie, Tampa Bay
mattie

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Reply with quote  #45 
That is some great thinking for sure. nice work!
The tops of the U's on the risers could have a slight fall from the hot to cold side too to aid drain back (it seems like one has i the drawing anyway).In fact all the way to your drain back tank will help(Im sure you both see this already)

This is the first time ive heard of a vacuum breaker(I've lead a sheltered life [wink])
Regards Mattie
stmbtwle

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Reply with quote  #46 
As the tops of the "U"s would only be a few inches wide, I don't think it would matter, and the fittings are 90 degrees anyway. Could simply tilt the whole collector a bit, though.

Wonder if putting fins on the tubes would help with heat transfer (assuming there is room for them)?

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #47 
Willie, agree about the fins, for additional heat pick-up...

In actual fact, hopefully the fins will be BOXES, like this:

SHELF-STEEL AIR DUCT.JPG

but painted BLACK, and not white...

They will have to be force-fitted as it is, since I only have about 40 mm width to play with (1.5 inches) and the box as shown is about 33mm.
The copper I intend to use would be 28 mm OD.
Would have to fit PVC bushes over the copper, to prevent it from touching the galvanized steel...

Like you said to Mattie, the top connections between the risers would be about 20 cms maximum; even if they were perfectly horizontal, I guess they would shed the water OK, at drainback.  Otherwise I could use a round bend like this big guy on the right... (provided it exists in 28 mm, that is...).
Main Image

G_H



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(1)  "Heat goes from hot to cold, there is no directional bias"
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Garage_Hermit

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Reply with quote  #48 
er... Just wondering what the reaction would be if I said I was thinking of mocking this idea up, from black polythene, like this...

[image]
The tops of the risers would be simple 180-degree bends (no fittings).

ER...  Second Question: would it thermospihon any, if the end of the blue pipe was immersed  in one barrel, and the end of the red pipe in a second barrel ?

G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
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stmbtwle

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Reply with quote  #49 
I can't say about thermosiphon. I kinda doubt it, but there's one way to find out for sure...

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Willie, Tampa Bay
SolarInterested

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Reply with quote  #50 
Doesn't the storage tank have to be above the collector for a thermosiphon to work?
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