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Garage_Hermit

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Reply with quote  #1 
I thought I would play around with an idea that I had here thanks to a suggestion from Willie...  http://www.simplysolar.supporttopics.com/post/hybrid-collector-for-a-vertical-facade-6918046?trail=20#11

This HEX might be of use to somebody wanting to locate an AIR collector some distance from the point of use, and its main advantage would be avoiding having to trench for big ducts: instead, a slimline trench for PEX tubes would suffice.

The other advantage I'd hope to see, is that compared with a "standard" hydronic collector, the air collector could be run *cooler* by blowing out the air and getting all the heat into the (heavily insulated) water tank.

Another design objective [frown] would be to build the HEX as economically as possible, so that it worked out cheaper than the cost of an equivalent hydronic collector...

Modified for Supplemental Design Objective ( [rolleyes] )

The collector could be run at NIGHT in Summer,  to generate cooling effect...

[image]

G_H

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stmbtwle

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This brings up a question: Which is more efficient, running air ducts say 10 meters out and 10 m back, or using a hydronic collector, then through 10 meters of PEX or PVC, to a water-air heat exchanger, and back to the collector?
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Willie, Tampa Bay
SolarInterested

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Reply with quote  #3 
Not sure about efficiency but I suspect the hydronic system would be easier to build and operate. Burying and insulating 10 metres of ducting would be a pain.
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Garage_Hermit

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Reply with quote  #4 
I suspect ducts are "a necessary evil" whereas pipes or tubes sound more "user-friendly".

What leads me to this statement, is, I reckon that AIR is actually a poor conveyor of heat...

Air is "OK for local use" - a close-coupled collector, delivering directly into a basement etc.
Air does warm up fast, but you need just so much of it to deliver any heat...

So the above HEX is an attempt to dispense with air as soon as possible: AIR is useful in a solar collector,
because it heats up quick, and an air collector is an easier and cheaper build than an hydronic collector.

The idea of the HEX is to allow "remoting" of an air collector, without the hassle of having to run the big ducts...

So, not so much of an "hybrid collector", as an "hybrid collection system" [smile]

BTW, the drawing is just  schematic - in the event, I guess two or more downspouts could be used, ganged to the same fan, to get a reasonable airflow...

G_H

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stmbtwle

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Reply with quote  #5 
I can see the reasoning for an air collector if they can be mounted on the side or roof of the space to be heated, and for something like a workshop you don't need to store the heat. But if one needs to move the heat any distance or store it till later, it seems to me that water is the way to go.
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Garage_Hermit

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Reply with quote  #6 
Willie, I have to agree !

Guess my hybrid HEX will never get off the ground !

G_H

wow, not so fast, guess we are forgetting the night-time cooling effect ?
so don't let's scrap it just yet [redface]

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stmbtwle

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Reply with quote  #7 
You can make it "fly" but I think you'll have to make it a LOT lighter (less complex). If I can make a HEX that will fit into a 2' x 4' collector, you can build one that will fit your facade. All you need to do is get a round tuit. [wink]
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Garage_Hermit

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Reply with quote  #8 
OK, Captain !

(posting now...)

G_H

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stmbtwle

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Reply with quote  #9 
Here's a link from the greenhouse section.   Should work in your case.  Once the heat has been transferred to the water, you can pump it anywhere.  No need for a wheelie bin in your driveway!

Another option would be to make a CPVC/aluminum absorber (same as Scotts cpvc/aluminum collector but without the box) and put it up behind the slate.  The fins would collect the heat and transfer it to the water in the tubing, and then you can pump it to wherever you like.  Couldn't get much simpler, you wouldn't even need to paint it black.

oops sorry http://api.viglink.com/api/click?format=go&jsonp=vglnk_141495770657719&key=ccc2217bc2b75c4bdf5f7e57267f0464&libId=933bbd5c-4903-4819-93a3-1429330c80ae&loc=http%3A%2F%2Fwww.simplysolar.supporttopics.com%2Fpost%2Fpassive-design-greenhouse-with-heat-exchanger-6833398%3Fpid%3D1282197381%23post1282197381&v=1&out=http%3A%2F%2Fwww.builditsolar.com%2FProjects%2FSunspace%2FGreenhouseHX%2FHeatPumpEnergyStorage.pdf&ref=http%3A%2F%2Fwww.simplysolar.supporttopics.com%2F%3Fforum%3D333286&title=Passive%20design%20greenhouse%20with%20heat%20exchanger.%20-%20Simply%20Solar&txt=http%3A%2F%2Fwww.builditsolar.com%2FProjects%2FSunspace%2FGreenhouseHX%2FHeatPumpEnergyStorage.pdf

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Garage_Hermit

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Reply with quote  #10 
Good link, Willie  ! I have seen it before, in fact, and know it as "Russell's G/H".

Reading it again, I am just about doing the exact same thing as Russell: using a "intermediate massive storage" as a heat buffer.

And like him, I want it to work at night in summer...

=================

Regarding pinching Scott's technology, I agree, but the technical difficulties of accessing the facade outweigh the benefits...
Basically, the turning radius of PEX is too wide to fit my structure (I have vertical rafters on 36-cm centers...
Could not get enough density of pipes (thus water volume) per square meter of slate...

To give U an idea of scale, inserting PEX (even the thin 1/2-inch stuff) inside the facade is like operating on one's toe nail using the ISS robotic arm with a 20-inch torque wrench duct-taped on the end......

Not impossible but "difficult"...


I will nonethelss make up a prototype and take some pictures of it, to illustrate my situation

Cheers,

G_H

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