8 Channle Relay Modul Controllplatine
You just need 2x PCF 8574AP portexpander, 2x 4.7k resistors, 1x LCD Display, 1x Infrared Display, an ADT22100 temperature sensor and a 8 Channle Relay Modul.
You connect the LCD Display with one of your PCFs and the Relay Modul with the second one. Just like shown on the plan (if you want to change it a bit you have to modify the sketch ;)).
Once done you just have to connect the SCL and SDL inputs from the Expanders with the SCL and SDL Pins of the Arduino :D. Remember to use 2x 4.7k pull up resistors.
Please use for the Relays on the Modul an other voltage source than the Arduino. Otherwise there is a risc to damage the Arduino.
Maybe you also need to change the IR Codes in the sketch (can be found in the loop routine) in order to get it working with your own zapper ;)