Posted by Father Haskell on December 22, 2008, 1:17 am
Build a labyrinth-shaped "mold" from scrap ply and 2 x 4. Lay the
ducting into the labyrinth. Cover with another sheet of plywood
and stand on top to squash the pipes to a uniform, 1-1/2" thick,
already bent and ready to install into the box.
Posted by nicksanspam on December 21, 2008, 6:46 pm
Why use a tube at all?
Posted by schooner on December 21, 2008, 7:45 pm
Why not? It is just another form of collector. It acts as both the
collector plate and ducting in one basically. The dry duct also affers a
bigger surface area with the grooves and they also disturb the airflow to
improve heat transfer to the flowing air. The tube design is just one of
many collector designs, be it a flat plate, screen, felt, etc.
What do you feel is the best overall design? Be interested to hear various
options and opinions.
Posted by Morris Dovey on December 21, 2008, 8:53 pm
Would not the best overall design use all available plenum cross
sectional area to minimize friction (maximize airflow) and keep
everything in the absorber plenum at the lowest possible temperature to
minimize re-radiation and conductive losses - while presenting the least
amount of friction-producing wall surface area?
And would not the best absorber not have a geometry in which fully half
of the absorber was positioned to re-radiate toward either glazing or
box wall - and would it not also have the lowest possible thermal mass
and produce the least resistance to airflow?
Of course, carrying those factors to the extreme might not result in
either the cheapest nor easiest design - but "cheap and easy" may not be
fully compatible with "best". :)
DeSoto, Iowa USA
Posted by schooner on December 21, 2008, 9:47 pm
Well with little airflow resistence and the lowest possible tempurature youd
have little heat transfer so I don't see the value.
I prefer practical ideas to theoretical ones personally. If you cannot
easily build it for a reasonable cost and have it produce a useful amount of
heating then it is of no value, you may as well use tradtional heating
sources as in the end it will be simplier and cheaper.