Lakshmi, ON/OFF control will work and will be similar to the temperature control in a home. The downside of ON/OFF control is that the valve will always be "hunting" or, if you prefer, oscillating around the setpoint. If this is acceptable and the valve maintenance issue (from moving often) is not a problem, then I think your plan will work. You have described (in your original post) what is called a proportional only control (P controller or ON/OFF control ). If you choose to use the PID algorithm and the temperature response is fairly fast, then a PI controller (set derivative = 0) will work well. Does the setpoint ever change or will it be the same always ? regards, randy
