Hi,
From what I can get from your code, you are controlling a HHO generator cell.
You are monitoring the temperature and some other parameters.
As the cell is a current load, not a voltage load, you should be measuring current.
HHO production is proportional to current through the cell, not voltage.
Measuring voltage will not give you a HHO production value because the resistance of the cell changes with volume, temperature and electrolyte concentration.
Current will be an almost direct incication of molecular HHO generation.
Is this what you are trying to accomplish?
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
A complete CIRCUIT diagram will help, not a picture of parts.
Can you please tell us your electronics, programming, Arduino, hardware experience?
Tom.... 