I quickly put together a small program that I hope will get you closer to what you need.
It should print out to your serial port as CSV format and also, it should control an output to which you can connect a relay for heating.
I haven't tested it, but it compiles fine in Eclipse.
You will need to either copy and paste the code or rename the file from copjohn.cpp to copjohn.ino
In the code, there are notes at the beginning to give you more information and the code is documented and is kept simple with no special tricks.
Attached is a PDF of the code as well from Eclipse, which may appear neater. I use tabs as my delimiter, not spaces, so the neatness of indentation and comments will be spoilt if you import into Arduino IDE, which uses spaces.
Paul
copjohn.cpp (5.63 KB)
copjohn.pdf (34.8 KB)