set terminal png
set output 'temperature.png'
set xdata time
set timefmt "%b %d %H:%M:%S %Y"
set title "Munchkin Supply and Return Temperatures (F)" 
set ylabel "Circulating Water Temperature" 
set yrange [30:150]
set xrange [*:*]
set xlabel " "
set grid
set size 1.2 ,0.5
set key top left

plot 'munchkin_temperature.data' using 1:(($5 * 1.8) + 32) t "Supply" with lines, \
     'munchkin_temperature.data' using 1:(($6 * 1.8) + 32) t "Return" with lines, \
     'zone.data' using 1:($5 * (1 - $6) * 35) t "Heating with Munchkin gas boiler" with points lc rgb "blue", \
     'zone.data' using 1:($5 * $6 * 35) t "Heating with stored solar energy" with points lc rgb "brown"