Posted by Curbie on May 30, 2009, 6:37 am
Very interesting advice, the spread-sheets have been pointing me in
the same direction, there seems to be a few ways to look at it:
Cost per Ft.^2.
Cost per BTU.
Cost per supplemental BTU. (If the array doesn't supply all the heat I
The Cost per Ft.^2 view seems to have a strong tail-wind and I was
confused if the numbers were telling the full story or if my desire to
handle water heating and as much space heating as possible were
pushing me in a different direction than the prevailing wind.
Posted by Morris Dovey on May 30, 2009, 4:42 pm
That /is/ interesting!
Of the three, only the third cost basis tells a 'real' story (but only
if you consider the cost/supplemental BTU to be reasonably predictable).
The other two depend heavily on real (as opposed to statistical)
predictability of actual future insolation, which looks pretty much like
a crap-shoot to me - I'd prefer to /always/ be comfortable rather than
achieve a too hot/too cold /average/ that falls into my comfort range.
It's at this point in the thinking process that most people seem to
become so distracted with cost considerations that they forget that the
original objectives were to live comfortably and enjoy a reasonable
supply of hot water. :)
If you can produce designs for either/both types of heaters that meets
your needs and can be fabricated with off-the-shelf materials, then
there are strong odds that you'll be spending your money well.
I'd also do separate water/air systems with a modular approach that
allowed adding capacity to either - and, if part of either system was
damaged, easier maintenance (which will become important as /you/ age)
and allowed uninterrupted function at reduced performance until repairs
DeSoto, Iowa USA
Posted by Curbie on May 30, 2009, 6:14 pm
I'm leaning towards an aluminum-FIN & copper-TUBE collector design
outlined on builditsolar.com, he has testing data on this design out
there and feels that this is on the order of 6% less efficient at
25-33% of the cost of a commercial unit. I've had brief contact with
the owner of the builditsolar site his answers to my questions have
been clear, to the point, and very helpful. I'm looking to go as large
as roof area permits and have settled in on a water system because I
have use for summer-time heat.
Posted by Lord Gow333, Dirk Benedict's n on May 30, 2009, 1:42 am
IF the corn stove people's numbers are right (yeah, I know...) corn should
still be more economical.
Regardless, my point here is that it still makes more sense (to me anyway)
to burn the corn as is rather than go thru all the processing for ethanol
and then burn it anyway. Then take all the heating oil saved and run it in
As for me I burn wood because I have it, but if I had to buy fuel I'd
probably be playing corn and wood pellets off of one another.
BTW, ear corn is even cheaper than shelled corn, and burns like all hell in
a regular wood stove. :-)
LG (lost a grate that way)
"Keep it simple. If it takes a genius to understand it, it will never work."
- Clarence Leonard "Kelly" Johnson
Posted by Steve Ackman on May 30, 2009, 6:30 am
21:42:38 -0400, Lord Gow333, Dirk Benedict's newest fan!, firstname.lastname@example.org
Hmmm... maybe it's the difference between living at
the edge of the cornbelt as you apparently do, vs.
northern NH as I did.
No argument here. I planted a few hundred soybean
plants to try those in the pellet stove. They burn
great mixed with wood pellets. Oh, and drizzling your
old motor oil over the pellets is another way to burn
it cleanly and turn "waste" into useful energy.
Corn wasn't even close to being in the running for us.
I'd certainly have tried some of the wood bricks if they
were available. The only place within 50 miles that
carried them was sold out when we called, and doubted
they'd get any more for that season.
I dried a few bushels of sweetcorn to that end also.
Didn't burn it alone though, just tossed a few ears at
a time on the logs.