Posted by David L. Jones on June 21, 2005, 3:23 am
Would there be much disadvantage in using a plastic box as opposed to
the more traditional galvanised steel box with insulation?
Posted by Gary on June 21, 2005, 1:55 pm
David L. Jones wrote:
I guess the thing to watch out for would be exposing the plastic to
higher temperatures than it can stand. If you insulate the space
between the absorber cavity and the plastic sides and back, then I
would guess that plastic would be OK. Wood seems to work OK.
I've talked to one of the authors of the Solar Air Heating Systems
book that I mentioned in the post above about this,and he is a strong
supporter of metal boxes.
I've wondered about using some of these new plastic/wood composite
decking materials for the sides of the collector box. It seems like
if you could figure out a good way to keep them from getting to hot,
and work out a good design for the corners, they would have the
advantage of looking nice and lasting a long time??
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Posted by Morris Dovey on June 21, 2005, 2:44 pm
[I missed the original post]
Plastic is vulnerable to UV. Galvanized steel and aluminum are vulnerable to
salt and corrosive pollutants.
Temperature shouldn't be a problem with plastics if the design provides for
prompt removal of heat from the collector. (-:
I've been using wood with good results (and I think Gary has had the same
experience) - and I'm about to test a relatively new wood-acrylic composite
that's available in 4'x16' sheets for portions of collector boxes that are
exposed to the weather. I'm expecting thermal behavior and longevity
comparable to wooden boxes; but a substantial increase in my ability to
procure material of consistant dimension and quality.
Posted by David L. Jones on June 27, 2005, 12:35 am
Morris Dovey wrote:
I've decided to build my box out of wood, but am now thinking about
potential effects of chemicals used in some system components and if
they will be picked up and introduced into the air system.
I was going to have just the bare wodden box inside, but I will now
line it with aluminium foil to prevent any treatment checmicals from
the wood mixing with the system.
"Treated Pine" for instance has recently been baned in Australia due to
the chemical used being cancer causing or something along those lines.
I'm now thinking of using regular "untreated" pine and painting it
externally for weather protection, but I'll still use the aluminium
anyway just in case.
Anyone had any experience with chemical pickup into air systems?
I'm also worried about PVC piping (thinking of using this for some
sections of ducting) and silicon sealant which will be used to seal
everything inside the box.
Posted by Morris Dovey on June 27, 2005, 3:55 am
David L. Jones (in
| I've decided to build my box out of wood, but am now thinking about
| potential effects of chemicals used in some system components and if
| they will be picked up and introduced into the air system.
I've avoided treated wood; but paint both inside front and exterior of
the box (and have been experimenting with shellac for air conduits.)
I've found that volatiles from my paint and shellac "cook out" fairly
| I was going to have just the bare wodden box inside, but I will now
| line it with aluminium foil to prevent any treatment checmicals from
| the wood mixing with the system.
IMHO, the aluminum foil probably isn't worth the trouble. If you don't
treat the wood with harmful chemicals, then chemicals won't be a
| "Treated Pine" for instance has recently been baned in Australia
| due to the chemical used being cancer causing or something along
| those lines. I'm now thinking of using regular "untreated" pine and
| painting it externally for weather protection, but I'll still use
| the aluminium anyway just in case.
This sounds like a winning approach. :-)
DeSoto, Iowa USA