problem with the conditions at the thermometer

Hi, I have a problem with the following program. I can not operate the conditions at the end of the program. It's well written? Thanks for the help

void loop(){

sensors.requestTemperatures(); //na?tení teploty z ?idla Tpanel = sensors.getTempC(PANEL); //teplota panelu

//smaž LCD lcd.clear();

lcd.setCursor(0, 0); //nastav první ?ádek lcd.print("Teplota panelu:");

lcd.setCursor(0, 1); //nastav druhý ?ádek lcd.print(Tpanel); lcd.print(" stupnu"); //teplota panelu

if (30 >= Tpanel); //pokud je teplota panelu stejná nebo menší než 30 stupnu, pak

digitalWrite(rele, HIGH); //vypni ?erpadlo digitalWrite(led, LOW); //zhasni diodu

if (Tpanel >= 40); //pokud je teplota panelu stejná nebo v?tší než 40 stupnu, pak

digitalWrite(rele, LOW); //zapni ?erpadlo digitalWrite(led, HIGH); //roži diodu

delay(1000); //?ekej 1s

}

You have superfluous semi-colons on your if statements and, I suspect, missing braces. This:

if (30 >= Tpanel);  //pokud je teplota panelu stejná nebo menší než 30 stupnu, pak
   
   digitalWrite(rele, HIGH);  //vypni ?erpadlo
   digitalWrite(led, LOW);   //zhasni diode

Should probably be:

if (30 >= Tpanel)  //semi-colon removed here
   {
   digitalWrite(rele, HIGH);  //vypni ?erpadlo
   digitalWrite(led, LOW);   //zhasni diode
  }