Automatic FART EXTRACTOR / Bathroom Dehumidifier Fan

/* Automatic fan control for bathroom humidity
 * humidity threshold set by a potentiometer 30<->90%
 * pushbutton for manual activation 15 minutes
 * 
 *  Viorel Racoviteanu
 *  https://www.youtube.com/channel/UCiRLZX0bV9rS04BGAyUf-fA
 *  https://racov.ro
 *  YO3RAK@gmail.com
 *  
 * I cannot take any responsibility for missuse of this code
 * or any kind of damage it may occur from using this code.
 * 
 * nov 2022 - first release
*/

//Libraries
#include <DHT.h>;
DHT sensor(3, DHT22);   // Initialize DHT22 on pin 3

//Variables
unsigned long NowTime;    //Store the current millis() for timing purposes
int hum_set;              //Stores set humidity threshold
int hum_read;             //Stores real humidity
int temp;                 //Stores real temperature
String fan;               //colud be ON of OFF, for serial display

void setup()
{
// pin declaration
  pinMode(A6, INPUT);     //potentiometer pin
  pinMode(3, INPUT);      //DHT22 sensor pin
  pinMode(4, OUTPUT);     //relay pin
  pinMode(13, OUTPUT);    //LED pin
  Serial.begin(9600);
  sensor.begin();
  
// splashscreen
  Serial.println();
  Serial.println("     *****    FART EXTRACTOR, nov.2022    *****");
  Serial.println("Viorel Racoviteanu, https://racov.ro, YO3RAK@gmail.com");
  Serial.println();

  digitalWrite(13, HIGH); // activate relay and led
  digitalWrite(4, HIGH);
// the reset is manual activation for 15 minutes
  Serial.println("Manual activation 15 minutes");
  Serial.println();
  for (int i = 0; i<(15*60); i++){
    delay (1000);
  }
  NowTime = millis();
  digitalWrite(13, LOW);
  digitalWrite(4, LOW);
  fan = "OFF";
  NowTime = millis();
}

void loop()
{
//Read the potentiometer for set humidity threshold
//transforms potentiometer voltage into threshold value
  hum_set = (map(analogRead(A6), 0, 1023, 30, 90));
//Read sensor data every 2 seconds
  hum_read = sensor.readHumidity();
  temp= sensor.readTemperature();
//Print temp and humidity values to serial monitor
  digitalWrite(13, HIGH);     //blink LED
  Serial.print("Rh%:");
  Serial.print(hum_read);
  Serial.print(", Set:");
  Serial.print(hum_set);
  Serial.print(", Temp:");
  Serial.print(temp);
  Serial.print(", Fan-");
  Serial.println(fan);
  delay (100);
  digitalWrite(13, LOW);
//if threshold exceeded
  if(hum_read > hum_set) {
    fan = "ON";
    digitalWrite(4, HIGH);    //activate relay and led
    digitalWrite(13, HIGH);
  }
//if threshold not exceeded (with hysteresis)
  if(hum_read < (hum_set-3)) {
    fan = "OFF";
    digitalWrite(4, LOW);    //deactivate relay
  }
  delay(2000);
}