Solar air heater - what glass is best?

[JERD]

I am wanting to construct a solar air heater (not hot water) to mount on the
roof of my house.

What is the best glass to use for this? I have seen some commercial units
manufactured with a 'dark glass'.

Is there a better alternative to glass?

Any (URL) pointers to home made units?

JERD

 

[Nick Hull]

I am wanting to construct a solar air heater (not hot water) to mount on the
roof of my house.

What is the best glass to use for this? I have seen some commercial units
manufactured with a 'dark glass'.

Is there a better alternative to glass?

Any (URL) pointers to home made units?

JERD

Plastic is a lot cheaper and more durable. There is a lexan
sheet that is hollow for this purpose, it has square tubes
inside. About $70 per sheet, you do have to keep the ends closed
to keep insects out.

 

[Ecnerwal]

I am wanting to construct a solar air heater (not hot water) to mount on the
roof of my house.

Is there a better alternative to glass?

Low iron glass is the "best glass" (but spendy since it's unusual).
Twinwall or triwall polycarbonate (available from any decent greenhouse
supplier) is probably the "best glazing product", particularly if price
matters. You can order the stuff online, but with shipping costs, it's
probably cheaper (at least for non-huge orders) to drive to a properly
stocked, quasi-local greenhouse supplier. It's about an hour from me to
the nearest one.

This is the "default online supplier", and they have good information
about using the product, allowing for thermal expansion, etc.

http://www.sundancesupply.com/

You should either have a setup for venting in the summer, or cover the
panels in the summer, or both. Stagnation temperatures under hot full
sun conditions can melt plastics, burn wood, etc...

 

[Trygve Lillefosse]

What is the best glass to use for this? I have seen some commercial units
manufactured with a 'dark glass'.

Do not think that dark glass is a good option, as the glass itself
will stop a lot of the radiation. So you end up with a wery hot glass,
but the inside will not be that hot.

You should have a glass that lets trough as mutch radiation as
possible, so that the heat becomes trapped after it passes.

 

[J G M D]

http://www.theworkshop.ca/energy/collector/collector.htm
i hve built a 90 and 288 can model work great!!

20C going in over 70C coming out mid winter in Nova Scotia

the whole msite is good

Gerry

 

[Trygve Lillefosse]

http://www.theworkshop.ca/energy/collector/collector.htm
i hve built a 90 and 288 can model work great!!
20C going in over 70C coming out mid winter in Nova Scotia

Impressive.

I get tempted to try a project like that.
If so, I guess I should include a small solar panel conected directly
to a small fan. This because I would like to get the heat into the
basement, where I already have a heatpump, so that convection can lead
the heat upwards.

Only thing is that the cans have a refound of NOK 1.-, wich is CAD
0.18 / USD 0.175

Thinking about it, I have a beasement window where I could get a
couple of pipes trough. Not sure about how much sun it gets though.

 

[Morris Dovey]

JERD wrote:
| I am wanting to construct a solar air heater (not hot water) to
| mount on the roof of my house.

I'm curious as to why you'd want to mount it on the roof of your home,
since you'll need to coerce the air from where it's warmed to where
you want it - and because the default orientation (sloped or flat to
match the roof pitch) will keep it in operation year-round...

| What is the best glass to use for this? I have seen some commercial
| units manufactured with a 'dark glass'.
|
| Is there a better alternative to glass?

I think so, but then I'm located in an area with occasional large
hail. My preference is for twinwall polycarbonate.

| Any (URL) pointers to home made units?

I'm not sure that these will fit your criteria for "home made", but
they may provide a bit of food for thought - at
http://www.iedu.com/DeSoto/SC_Madison.html you can see photos of
construction and installation.

There are links at the page below to other information you may find
helpful/interesting.