Posted by Gary on February 25, 2004, 8:34 pm
I finished the solar barn project -- thanks for all the suggestions.
I put a description, comments, and some early performance numbers at:
I'd appreciate any suggestions for improvements.
Let me know if you have any problems with the link
Posted by Jerry Ellinghuysen on February 26, 2004, 3:54 pm
Posted by David Delaney on February 26, 2004, 5:08 pm
On Wed, 25 Feb 2004 13:34:54 -0700, "Gary"
Congratulations on an impressive project and
What was the thickness, composition, source, and
method of attachment and hinging, of the flapper
It would be useful to provide this info on your
David Delaney, Ottawa
Posted by nicksanspam on February 26, 2004, 6:27 pm
Nice work :-)
I've used dry cleaner bags with duct tape over the upper edge and
staples through the duct tape. Hinging them higher than the upper edge
of the vent holes would reduce the bouyant air force and temperature
required to hold them open, and making them one continuous flap vs
individual flaps would tend to reduce air leaks when they are closed.
You might manually hold them open for a few minutes a few times
during the day to see if that reduces the outlet air temp, compared to
I used these valves on a large sunspace with flexible polyethylene film
glazing, and had a problem with them opening and closing on windy nights
as the wind flexed the glazing, which pressurized and unpressurized the
sunspace and pumped air into and out of the valves...
Posted by Gary on February 26, 2004, 9:51 pm
I used the design pretty much as described by Nick above.
I cut rectangular pieces out of Costco kitchen size garbage bags. They are
about an inch larger than the vent opening all around. I just stapled them
across the top.
I must say I had some doubts about whether this scheme would work, but it
works fine. During the day, the flappers blow out to around a 45 degree
angle, and do not appear to offer any significant resistance to flow, but I
will see if I can measure any difference.
I initially tried the flappers without anything to keep them from being
sucked into the collector during reverse flow at night, and they do get
sucked in. As Nick recommended, I added wire mesh across the vent openings
under the flappers, and this works fine. The flappers appear to seal well
against the wire and edges of the vent opening.