I want to make a furnace controller by PID and SSR that can control temperature of the precision of .1 degree.Would you suggest me some controller and SSr that can do this job
You have to use a RTD or IC Sensor for more measurement accuracy. The control accuracy can be obtained by a Auto Tune PID controller and Thermally Optimizing the System or Equipment. That means Heat Transfer, Sensor Position, Sensor Size, Heater Type, Fans, Thermal Inertia and many things that can be studied by experimenting or learn it from the field engineers.
If the system is a small chemical bath you need to stir with motors for convection, if it is an Oven a Fan for air circulation may be required. The control signal from the controller can be a PWM pulse train or 4-20mA depending on what you drive. A pulse train for a DC SSR or 4-20mA for a DC Drive. The Controlled Actuator may be a Heater, Fan or Compressor.
If it is a temperature of 20 deg C, that needs to be controlled and the product is for the global market. Then you need a heater to bring a temperature to 20 deg in Alaska, but in Congo a 20 deg can only be obtained by Cooling the system.
A Block Diagram showing how a Temperature Controller and SSR is used in Control. For Furnace more SSRs and more Heaters have to be used.
Create SSR banks in the control panel and many Heaters well distributed in the heating area. Use a PID or Proportional controller with On/Off output for SSR control.
For very Large Systems use a Booster Heater bank and Separate Controller only for the Start Up.
See my Temperature Measurement and Control you will understand better.