Procida) wrote:
> NT <meow2...@care2.com> wrote:
> > On Nov 19, 12:28 pm, real-not-anti-spam-addr...@apple-juice.co.uk
> > (D.M. Procida) wrote:
> > > NT <meow2...@care2.com> wrote:
> > > > I think the gold standard for air heaters is 3 layers of black
> > > > shadecloth fixed in its frame at an angle like so:

> > > > air in at bottom, out at top. Glazing is on the right. Unheated income
> > > > air touches the glazing, heated air never does.
> > > > : = shadecloth

> > > > .  ______
> > > > .       :||
> > > > . ||   : ||
> > > > . ||  :  ||
> > > > . || :   ||
> > > > .  _:____||

> > > That - also:

> > > <http://wiki.diyfaq.org.uk/index.php?title=Solar_Thermal#Space_heating>

> > > looks a lot simpler than the kind of thing I was looking at (e.g.:

> > > <http://hackedgadgets.com/2011/11/16/solar-pop-can-heater-system-build-r
> > > oundup/>

> > > It's not clear to me what advantage one system would have over the other
> > > in terms of effectiveness.

> > > Daniele

> > With the shadecloth collector, heated air never comes in contact with
> > the glazing. This much reduces glazing heat loss. With cans, heated
> > air is generated on both sides of the can. The hot air outside the can
> > meets the glazing, and heat loss occurs.

> > Hot surfaces radiate heat away. Black drink cans simply radiate this
> > back out (their silver interior doesnt). Shadecloth reradiates in both
> > directions, and the multiple layers mean that a lot of the reradiation
> > is blocked from existing the collector.

> > The shade cloth collector allows free flow of air, so if mounted on a
> > wall, no fan is needed. Parallel strings of cans arent quite as good
> > in this respect, and a bit more fan power is needed when roof
> > mounting.

> I'd need some kind of fan anyway, as this thing will be mounted on the
> roof of the garage.

> What exactly is shade cloth? I have some dark blue blackout blind
> material hanging round - would that do?

> How does the air filter through the shade cloth? There's a version here:

> <http://www.builditsolar.com/Experimental/AirColTesting/ScreenCollector/
> Building.htm>

> that uses aluminium mesh rather than cloth.

> > Finally the cloth collector is far lses work to make.

> Yes, certainly.

> Many designs seen to use nothing more than corrugated PVC rather than
> double-glazing, which seems like an odd choice when large double-glazed
> panels can be had for nothing if you look in the right skip.

> Daniele