Posted by Morris Dovey on January 3, 2008, 8:21 pm
| As I am having my fifteen year old house painted, the painters made
| note that almost none of the "cracks" that are not visible from
| ground level have any caulk at all. There are gaps of 1/4" along
| the tops of some sliding glass doors, and unsealed gaps over every
| window. Some of the openings are large enough that they had to
| insert backing material before caulking.
Hmmm, indeed. Methinks you may be one of the fortunate people who're
/aware/ of the problems...
DeSoto, Iowa USA
Posted by nicksanspam on January 3, 2008, 9:10 pm
Sounds good, with a room temp thermostat and some hot shiny ceiling mass and
a vertical duct to let hot air return to the air heater without mixing with
Posted by gary on January 4, 2008, 4:12 pm
Thats a pretty good sized collector (190 sqft) -- seems like it should
do well for a shop that size in a moderate climate.
As you say, the slab should be good for heat storage.
You might be losing heat out the periphery or bottom of the slab if
its not insulated?
Or, adding wall/ceiling insulation coupled with better sealing
(usually awful on shops) might also help your solar go further.
You might think about adding more solar with one of these:
These are both simple and cheap and would give a boost in daytime
The 2nd one also provides outstanding daylighting in the shop -- it is
my all time favorite solar project mostly because of this daylighting
coupled with heat aspect, and its simple use of movable insulation.
Even my wife says that my shop is the usually the most pleasant place
to be in the house :)
Posted by EricY on January 4, 2008, 4:53 pm
Thanks for the info. I spent a lot of time on the insulation and sealing so
I think it's pretty tight. The slab is insulated with 2" foam around the
perimeter and 1" underneath (thus the slab is effectively floating).
However, there are two exceptions. I have a 3' pedestrian door where the
slab does not have a thermal break. In addition, there is a 9' garage door
where the slab is connected to a concrete apron with no thermal break. I
know i'm losing some heat there, so maybe I have to break out the masonry
blade and at the very least reduce that connection with the outside. I also
added more foam insulation to the garage door - that thing was a huge heat
sink. Before adding the insulation that corner of the shop was always
freezing (in as much as it freezes down here).
I like hot the air syphon - Morris suggested the same thing in another post.
My wife might kill me if I bolt anything else to the outside of the shop,
Despite the large amount of collector area I have a few things working
against me. First, the collectors are not tilted optimally for winter time
usage. Second, across the street are some 3 story condos that block the
sun, and they have some 50 ft oak trees that aren't helping (although the
leaves have all fallen off by now). Finally, the shop is not facing in the
ideal direction - more SE than due south. I hoped to compensate for these
disadvantages with more collector area.
By the way, any updates on your solar shed in the pipeline? How has the
Posted by gary on January 5, 2008, 3:46 pm
I don't think the SSE orientation should hurt much.
I understand that trees even without leaves can hurt some, depending
on the tree.
You might try the black can filled with water inside of a small glazed
enclosure (maybe a 2 liter pop bottle?).
Set up one in full sun and the other near you collector, and see what
the temp difference is at the end of the day.
There are some hand book methods that give heat loss per foot of slab
periphery -- that might allow you to guess at how much you are losing
in those two uninsulated areas. I can probably find something if you
don't have something at hand.
I've been kind of lazy about doing good performance measurements on
the Solar Shed -- its kind of joined the ranks of things that work and
don't get much attention. I do plan to make a few small improvements
this summer, but it seems to be doing fine -- we have not had a banner
year for solar heating here.
There is an article on it in the latest Mother Earth News, which is
available at their website as a free download -- there is a little new
info in the article, including a system plumbing/control diagram.