Two different problems, starting with simple temperature regulator

[johnerrington]

My advice would be it isnt going to work if you keep using delay().
Study this example

Blink Without Delay | Arduino Documentation

to see how to use millis()
then

Using millis() for timing. A beginners guide

Part 1 It is not usually long before new Arduino users discover that although the delay() function is easy to use it has side effects, the main one of which is that its stops all activity on the Arduino until the delay is finished (not quite true, I know, but that is usually how the problem presents itself). When this occurs the new user is usually directed to the BlinkWithoutDelay example sketch (BWoD) and/or the excellent thread entitled Several things at the same time. Several things at the…