Hello I am currently working on a project using an Uno, RTD temperature sensor, relay, and 1500W heating element. The basics of it is the Arduino will read in a temperature from the RTD, and based on that reading will or will not send out 5V to the relay which will allow the heating element to start up. The heating element will be powered by a 120V GFCI outlet. This is all working just fine, however I am trying to hold the temperature for a long period of time with +- .5 degree F and a simple on/off for the heating element will probably not be able to give me that precision.
What would be the best way to control the power to the heating element based on the temperature read of the RTD. What sort of electronics do I need and how to implement the Arduino PID library. Any point in the right direction would be greatly appreciated. Thanks.