   float tank_temp = sensors.getTempF(tank_sensor);
   float collector_temp = sensors.getTempF(collector_sensor);
 
-  if (tank_temp < 0 || collector_temp < 0) {
+  print_temps(tank_temp, collector_temp);
+
+  // Assume that very negative readings are errors
+  if (tank_temp < -50 || collector_temp < -50) {
     Serial.println("Screwy reading, ignoring");
   }
-  
+
   // If tank is hot enough, pump is off
   else if (tank_temp >= tank_max_temp) {
     Serial.println("Tank is over max temp, pump off");

  else {
  }

  print_temps(tank_temp, collector_temp);

  delay(60000);
}



float tank_max_temp = 140;      // Deg. F; above this, pump is off
float collector_min_temp = 40;  // Deg. F; below this, pump is off
float on_threshold = 10;        // Deg. F differential before pump turns on
float off_threshold = 10;       // Deg. F differential before pump turns off
int interval = 60000;           // Delay in ms between readings

/*
 * setup() - this function runs once when you turn your Arduino on
