Arduino Uno R3 yogurt maker code

const int mech = 2;
const int SSR = 4;

unsigned long timer1;
unsigned long timer2;
unsigned long timer3;
unsigned long timer4;

float Period = 10000; //ms
float DC = 0.99; //duty cycle
float Tset = 207; //deg F
float Vs = 4970; //supply voltage (mV)
float R1 = 1700; //ohms
float a = 1.47337E-3;
float b = 2.37225E-4;
float c = 1.07080E-7;
float cal = 1.0; //deg F
float Tinf = 71.0; //deg F

int error = 0;
int Vout = 0;
int R2 = 0;
int T = 0;
int x = 0;
int y = 0;
int r = 0;
int z = 0;
int s = 0;
int Q = 0;
int P = 0;
int n = 0;
int w = 0;
int d = 0;

void setup(){
  Serial.begin(9600);
  pinMode(SSR,OUTPUT);
  pinMode(mech,OUTPUT);
  digitalWrite(mech,HIGH);
}

void loop(){
  x = analogRead(A1); //Thermometer
  y = analogRead(A2); //Also Thermometer
  z = analogRead(A3); //SSR
  r = analogRead(A4); //Boil Switch
  s = analogRead(A5); //Also Boil Switch
  float Vout = ((x+y)/2)*(4970/1023.0);
  float R2 = (Vout*R1)/(Vs-Vout);
  float T = 1/(a + b*log(R2) + c*pow(log(R2),3)); //T in deg K
  T = 1.8*(T - 273.15) + 32 + cal; //T in deg F
  float error = (Tset-T)/(Tset-Tinf) + 0.002*(T-Tinf);

  if (d==0){
  Serial.print(millis()/1000);
  Serial.print(" ");
  Serial.println(Vout);
  timer4 = millis();
  d = 1;
  }
  if (millis()-timer4 > 1000){
    d = 0;
  }
  //delay(5000);

  if (T < Tinf){
    error = 1;
  }
  else if (error > 1){
    error = 1;
  }

  if (r > 50 && s > 50){
    Q = 2;
  }
  if (r < 50 && s < 50){
    if (Q == 2){
      Q = 0;
    }
  }
//...................(Heater Duty Cycle)............................................

  if (Q==2){ //--------------Boil Switch Only
    digitalWrite(SSR,HIGH);
    }

  if (Q==1 && millis()-timer1 <= error*Period*DC){ //Period*DC = Max duty cycle
    digitalWrite(SSR,HIGH);
  }
  else if (Q==1 && millis()-timer1 >= Period){
    Q = 0;
  }
  else if (Q==1){
    digitalWrite(SSR,LOW);
  }

  if (Q==0 && T >= Tset){
    digitalWrite(SSR,LOW);
  }
  else if (Q==0 && T < Tset){
    timer1 = millis();
    Q = 1;
  }
  //......................(Safety: Stuck SSR)................................

  if (P==0 && z > 50){
    timer2 = millis();
    P = 1;
  }
  if (z < 50){
    timer2 = millis();
    P = 0;
  }
  if (Q==2){
    timer2 = millis();
  }

  if (millis()-timer2 > Period){
    digitalWrite(mech,LOW);
    digitalWrite(SSR,LOW);
    while(true){ //Relays Off and Do Nothing
    }
  }
  //......................(Safety: Failed analogRead of Temp)................

  if (n = 1 && abs(x-y) > 56){// Difference of about 10 deg F
    digitalWrite(mech,LOW);
    digitalWrite(SSR,LOW);
    while(true){ //Relays Off and Do Nothing
    }
  }
  n = 1; //first reading eradicate
  //....................(Safety: Boil Switch Accidentally Left On)................

  if (w==0 && Q==2){
    timer3 = millis();
    w = 1;
  }
  if (Q != 2){
    timer3 = millis();
    w = 0;
  }

  if (millis()-timer3 > 12600000){ //Boil Switch Left On for about 3.5 hours
    digitalWrite(mech,LOW);
    digitalWrite(SSR,LOW);
    while(true){ //Relays Off and Do Nothing
    }
  }
   //.......................Safety: Thermometer Disconnect.............................

  if (Vout > 4960){
    digitalWrite(mech,LOW);
    digitalWrite(SSR,LOW);
    while(true){ //Relays Off and Do Nothing
    }
  }
}