Hi everyone, I’m working on a room temperature control system using an Arduino. I’m using a PT100 sensor with a MAX31865 module to measure temperature and two SSRs to control a heater and an AC unit. The Arduino reads the temperature and switches the heater or AC based on a setpoint, using a simple hysteresis control algorithm to avoid rapid toggling. I’m looking for suggestions on improving reliability, ensuring safe operation with AC loads through SSRs, and effective ways to simulate the system before connecting it to mains power. Any advice, feedback, or example designs would be greatly appreciated!
Google is often a helpful friend.
Hi, @mugdha321
Have you built a prototype?
That is on breadboard/protoboard and operated the SSRs, you don't need to connect the mains to them.
Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
Also links to hardware data/specs.
Thanks.. Tom.... 
or here...
Hi, @mugdha321
You could replace the PT100 with a potentiometer to simulate the PT100.
There are tables of figures that show temperature vs resistance that you can use to setup the potentiometer.
Remember PT100 means that the sensor has a resistance of 100R at O DegC.
Tom....
Depending on your set-up, using mechanical relays may be more reliable.