WHAt I wish to do is in the most cost effective way is: Measure 4 temperatures for an solar panel application. They are two 10mm copper pipes (Flow & Return), a sleeve in a Hot Water cylinder for the tank temp and the external temerature of the air. From that I would like to activate a pump based on...

I wish to measure 4 temperatures for an application. They are two10mm copper pipes, a sleeve in a Hot Water cylinder and the external temerature of the air. From that I would like to activate a pump based on a differential across two of the measurements. I would then like to replicate the above to a...