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stmbtwle

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Reply with quote  #31 
Yes, provided the nighttime temperature is cooler than the house. Generally though we want HEAT at night, and cooling in the daytime. That's the big problem around here, and why I don't have any need for hot-air collectors.

The Aretha Project has their own Facebook page, and a couple You Tube videos.  Well worth watchng.

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Willie, Tampa Bay

Garage_Hermit

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Reply with quote  #32 
Good vids, nice, thanks for the links !



this one proves that what's important, is getting the Right Message to the Right Audience...

[biggrin]

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...
solardan1959

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Reply with quote  #33 
Watched them both, neither helped me build a collector.  Second one was a good video though but a terrible waste of a good rose.  Maybe that's why I can't pick up women, presenting in the wrong format, or maybe it's the wife standing behind me with the frying pan....
mattie

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Reply with quote  #34 
Pardon my ignorance here if it blatantly appears,but what about replacing the fan and radiator heat transfer medium with a simple water enclosure at the top of the collector positioned for natural convection with a coil inside the runs out to the water tank.

The pump turns on at specific set point and sends heat to the external tank.It then shuts off when the temperature drops below another lower temperature? etc etc.

Another thing ive seen mentioned is that the expensive part is the water storage. Would something like this not make sense here?
http://www.builditsolar.com/Projects/SpaceHeating/EricsTank.htm

Regards Mattie
Garage_Hermit

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Reply with quote  #35 
well, Mattie, I guess that that would work, but natural convection is kind-of s-l-o-w...

(Great for a trombe wall, though...)

The collector catches the radiance, converts it to heat, and warms the air, so the more air, the more heat.
The more heat, the more hot water you get...
The more water you pump, the cooler the collector runs, therefore a cool collector absorbs more heat than a hot one...
etc.

We could also propose using natural convection to cool our car engine (in a cycle opposite to that of the Aretha); however the engine would break before it got cool enough [frown]

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...
mattie

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Reply with quote  #36 
My thoughts lay with the sealed unit and the stratification of the air.I can see that this stratification and slow transfer rate may cause other issues with possible stagnation?
stmbtwle

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Reply with quote  #37 
To start with, overall efficiency will be less because of heat losses at that high temperature.  Then there's possible (probable?) damage to the components.

I think in a really TALL collector it MIGHT work, not because of stratification but because of thermosiphon.   However I did three separate tests on that subject, with my smaller collectors and in all of them it did NOT work.  The collector hit possibly damaging temperatures every time, and this was with the pump running.  With the pump off, on a good day it would likely boil and start to percolate like an old-fashioned coffeepot. 

Speaking of percolating, I've found that it actually works in my all-copper-and-glass water tube collector.  With the pump off when it hits boiling (and it does), the steam pressure forces the water out through the top and down the line to the tank.  It's hot enough to warp any cpvc lines coming from the collector.  I had to put a check valve in the feed line to keep it from blowing back through the pump.

Might be a viable system in an ALL METAL collector that can take the heat.  Would I try it in a DIY with plastic or wood parts?  No way in hell!

However you're free to try it, maybe you'll come up with something I missed.


It's my understanding that the Model T Ford relied on convection and didn't require a pump, but that was before my time.  

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Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #38 

Mattie, it sounds like you propose replacing ARETHA by a BATCH storage !

I am sure I got you wrong and you do not propose that at all !

 I mean, the “R” in ARETHA means RECYCLING…

The same air gets churned around, ad infinitum.

I can’t see how the notion of stratification comes into it –  stratification implies a passive settling of layers due to gravity (density): ARETHA is all about DYNAMIC air, so the phenomenon is rather one of temperature-homogenization (save, mebbe, for a cold layer on the glazing, which we can afford to discount, so soon in the design process, it is a detail…).

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  #39 
Actually, ARETHA means "AiR Exchange THermal Assembly", not that it matters.

Go for it Mattie, you might invent a new type of collector.

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Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #40 
apologies, guys,
I'll let you get on with it and
return to my ... Aretha build [frown]

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...
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