fishingpol said:
Gary,
This is the place to be for wood burning in just about any heating appliance. It is good to see people doing projects while trying to get the most effiency out of their systems. There are a lot of people who are better wood consumers, including myself, that have gleaned tons of info here.
Your site has people building collectors directly on the side of houses. Is having the collector as close to perpindicular to the sun the best way to gain heat in a collector? Is it good enough that it just faces in a southerly direction? I have a south facing area on my house that I can put a panel, but I'm not sure if it is vertically positioned that it would be the most beneficial.
Jon
Hi Jon,
Vertical collectors against a south wall work out well for solar space heating. Reason being that the sun is lower in the winter, so it shines pretty directly onto a vertical collector. If there is a snow field in front of the collector, you can get a very beneficial reflection off the snow on vertical collectors.
Where we are (45 deg north lat), the sun only gets up to 22 degrees above the horizon on the winter solstice at noon.
Another advantage is that vertical collectors are much less likely to overheat in the summer because the sun is quite high and makes a large incidence angle with the collector.
I also like the look of vertical collectors, and they save some materials and labor -- its easier to just build one big frame on the wall that carries the full absorber area rather than building several separate smaller collectors of the same total area.
Also like the idea that you can keep the supply and return plumbing runs inside the collector and/or wall and avoid outdoor runs.
If a little tilt is desired, it would be relatively easy to still build against the wall, and kick the bottom out a bit for some tilt -- see the link just below.
One thing to watch out for on vertical collectors is the roof overhang. If you have a large (or even not so large) roof overhang, it will cast a shadow on the collector that cuts down output. A little of that is OK in mid summer, but you don't want the collector shaded by the overhang during fall, winter, spring. Good overhang tools here to check this on:
http://www.builditsolar.com/References/SunChartRS.htm#Overhangs
For DIY solar water heating only systems, I like a system with an excess of collector area, and a fairly steep (but not vertical) tilt. This way, you get good performance through the winter when most commercial systems fall off, and the steeper tilt keeps you from getting a lot of overheating in the summer. Like this system:
http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm
My new system does both solar water and space heating, and uses a larger vertical collector. So far, this is working out well. Even though the collector is much larger than we would need for hot water in the summer, it does not overheat due to the vertical orientation.
This is it:
http://www.builditsolar.com/Projects/SpaceHeating/DHWplusSpace/Main.htm
Still, a more tilted, or roof mounted collector can work fine too.
Gary