Change Arduino Code to Use Relay instead of Transistor (URGENT)

I have code for a project that uses transistor as on and off switch for a heater. The heater is 12v 100watts which is about 8.3 amps. The problem is my TIP122 transistor overheats. I am already using IN1 on this project for a solenoid. I would like to change the code to use IN2 to turn on and off the heater. This is the relay I'm using [login to view URL] and this is the heater https://www.amazon.com/gp/product/B016ZPLLOM/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 This is a sample of the code that needs to be edited. //////////////////////////////////////////// total = total - readings[index]; float temp = analogRead(tempsensor); //[login to view URL](temp); //delay(1); //Filter readings[index] = temp; total = total + readings[index]; index = index + 1; if (index >= numReadings) { index = 0; average = total / numReadings; LM35_control = (5.0 * average * 100.0) / 1024; // (T(°F) - 32) × 5/9 LM35_control = LM35_control*9/5+32; [login to view URL]("Temp: "); [login to view URL](LM35_control); [login to view URL](" F"); UpdateScreen(); } ////////////////////////////////////////// if (LM35_control<120) { analogWrite(heater,200); } else if (LM35_control>145) { analogWrite(heater,0); }//put your main code here, to run repeatedly: if (validReceived) { So if the temp is below 120 then the heater turn on. If above 140 then turns off. I need it done asap as I have customers waiting for product. Thanks,