..........so how will I use the error should I use a comparator and till the time the value doesnot become 0 keep the related equipment on some thing like that.........
yea osmthing like that ,,but lets put it this way
when your error is 0 (that means the heat is the same as the setpoint) then Kp*0=0 so no output and no changin anything
when your error has a number then you need to react someway,, this is how you determine kp.
so what you mentioned is just P ,,
, do you want to make all controls? P and I and D?
D helps you to run faster towards fixing your error when the error changes
do you need this property?
anyways that was a block diagram to understand the concept
you can turn it into a circuit the way you like,,
you can use a microcontroller,,or not ,,
the design can take many forms,