ATC: the more recent graphs are *more* accurate, but not the end-all-be-all. While giving a general idea of optimal base thickness in relation to other variables, I'm far from comfortable enought to say that the model can accurately translate to actual blocks. I believe it is fairly close though. Notice though that the if you look at a temp spread of .5-1 degrees covers quite a range of thicknesses.
ol'man: Entrance water temperature isn't a variable that I've put in just yet, it's hard coded to 25 C. When I get a chance to work on the program some more (55-60 hour work weeks plus many weekends have been impeding my progress) I'll make it an inputable variable.
I should be able to put some more time into the program and be able to add several features I've been thinking about this holiday weekend; we shall see.