This is a bit OT for alt.solar.thermal, but I think quite a bit of
know how there on this, and I read that group regularly... Google didn't
come up with any groups that often deal with this.
I'd like to add insulation to a few of my exterior walls. House is
20's vintage with a couple additions circa 60's and 70's. Frame house
with wood lap siding. Additions have siding over ~ 1/2" fiber board,
oddly additions are colder than rest of house. I think that is because
they have more exterior walls, even though the floors are much better
insulated. Climate, is moderate, Atlanta, Ga.
Cost is a bigger issue than end R value.
I've seen some new (to me) kind of blown in insulation that goes
through, I think, a 1" hole.
What I did was to pull a board at / near the top of the wall and
another near the bottom, and pulled bats through with a coat hanger. If
you are careful you can pull the boards with little / no damage other
than breaking the paint around the nails. That wasn't a problem for me
as I was planning to paint. Turns out it was for naught, I became so
disillusioned with the condition of the siding, I'm presently replacing
it all with Hardie board. I have 2 walls completely redone and the
difference is amazing. I recently painted the completed walls with an
airless sprayer and did one old wall as a holding measure. The old wall
still looks like crap, freshly painted crap, but nevertheless, crap.
For the walls, I'd look into the blown in cellulose that is "dense packed".
You can blow in either fiberglass or cellulose. I think the cellulose is better
for your situation in several respects -- there are some articles and tests
explaining why here:
If you are thinking about doing it yourself (which is feasible), I would get a
copy of the Bruce Harley book "Insulate and Weatherize" -- its very good and
covers cellulose installation in detail. Most of the home centers will loan you
a blower for free if you buy the insulation from them, but see what the Harley
book says about blowers that are suitable for dense packing.
You can do the job from inside or outside. If outside, the best way is to
carefully remove one row of siding down low, and another up high, then drill the
holes and blow the insulation, plug the holes, and put the siding back.
The person that runs the Yahoo forum called "Little Houses" is very good on this
subject -- you might try the archives there, or post a question.
If you have a crawl space under the house, you might have a look at it for heat
loss as well as the walls.
Got my new collectors up and running, and storage tank in, which now has about
450 gallons of water at 170F in it -- now I just need to finish the inside of
the house part to make use of it :)
I updated the Solar Shed description to show the new stuff:
<snip wall insulation stuff>
I'm working my way through all the info.
First, I'd like to say that's a fabulous picture of the solar shed
with the mountains in the background!
Thanks for all the info on the water tank (and the rest of course!).
Oddly I was thinking along the same dimensions. It seems like lower
heights give more storeage capacity for the same amount of EPDM liner.
The 3' height seems like a good compromise between volume and footprint.
How long did it take to get the tank up to temp? 170F is great! I'm
curious about how many therms you think the collector is yielding on a
typical day. My initial collector array here (6 - 2' x 10') will be
about a half the size of yours with plans to go half again larger (18 -
2' x 10'). I'm in a milder climate, but will have similar 1" polyiso
insulation, solkote coated home made (I doubt whether I've saved much)
instead of the superior commercial, and suntuf instead of twinwall.
I'm plugging away at the boxes and will put up some pics later...
One more comment on the tank. It turns out to be important to seal the lid down
well. I had some left over bat insulation over the top of the foamboard cover,
and it picked up a lot of moisture from the escaping vapor. I sealed all the
places I could, and then lag screwed down the cover. This is probably a good
idea from a safety point of view anyway -- I don't think a fall into 170F water
would be fun.
My differential controller has not arrived yet, so I was just turning the pump
on when the sun got on the collector and off in late afternoon -- I'm sure the
controller will be better. I was also fooling around with things all day, and
had the tank cover off part of the time. But, it went from about 80F up to 143F
the first sunny day. It lost about 5F overnight (something I need to improve a
lot). The next day was also sunny, and it went up to 175F by the end of that
day. The slope of the tank temperature plot looks like it would have kept going
over 175F had the sun not gone away -- i.e. the max temperature appears to be
somewhat greater than 175F. I plan to limit it to around 170F for the sake of
the EPDM liner.
I guess the first days gain implies:
Gain = (143F-80F)(441 gal)(8.3 lb/gal)(1 BTU/lb-F) = 230,600 BTU
For an 80% efficient furnace that would be 231/(100*0.8) = 2.9 therms
This is about (230600 BTU)/(240 sqft) = 960 BTU/sqft of collector
The books says we should be getting about 1850 BTU/sqft-day of sun now, so this
implies a very rough day long efficiency of 960/1850 = 52%
Not so bad, but I would hope to do better with the controller, better tank
insulation, and not fooling around with things all the time.
My initial collector array here (6 - 2' x 10') will be
I would think that with that much collector area, and your insulation upgrade
your heating bill would about disappear.
I would really like to hear how the Solkote works out, and how difficult it is
Nothing very exciting.
I got the old standby Goldline GL30
I looked at several others that had more bells and whistles, including some nice
logging and reporting features, but decided in the end that Goldlines long track
record for a reliable product was more important. If you got just the wrong kind
of controller failure, your collectors might be in danger of freezing.
I have a logger to track performance, so extra reporting features on the
controller would just be icing on the cake.
I got the Steca 301 and it works well with built in temperatures at
three locations (two used). It does not have adjustable differential
though. It has freeze protection but I do not use that (yet). It makes
no sense to do that on a drain down system, that I can see???
The Steca site displays a new model that will vary pump speed. They
report it will not be in N.America for another 6 to 8 months. I am
waiting for that one to appear as my pumps draws over 150W and it may
cut back on power after the initial water lift.
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