diff --git a/heater_v3.ino b/heater_v3.ino
index c8ca835..ea20e5a 100644
--- a/heater_v3.ino
+++ b/heater_v3.ino
@@ -4,6 +4,7 @@
 #include "config.h"
 #include "LittleFS.h"
 
+//////////////////////////
 // network
 
 IPAddress my_ip(MY_IP);
@@ -11,32 +12,33 @@ IPAddress gateway(MY_GW);
 IPAddress subnet(MY_NET);
 IPAddress sensor_ip(SENSOR_IP);
 
-// After how much time without connection we will 
-// reboot (in millis)
-#define NON_CONNECTED_REBOOT_TIMEOUT 60000 
-
+//////////////////////////
+// Base config
 // dht sensor
 #define DHTPIN D6
 #define DHTTYPE AM2301
 DHT dht(DHTPIN, DHTTYPE);
 #define DHT_UPDATE_INTERVAL 500
-
 // relay
 #define RELAY_PIN D1
-#define T_UPDATE_INTERVAL 500
-
-// external t
-#define EXTERNAL_UPDATE_INTERVAL 1000
 
+//////////////////////////
 // logic consts
-
+// After how much time without connection we will 
+// reboot (in millis)
+#define NON_CONNECTED_REBOOT_TIMEOUT 60000 
 // deviation from target t allowed (in degrees multiplied by 100)
 #define T_HYSTERESIS 150
 // relay cooldown temperature (after what t we allow to turn on relay again) (in degrees multiplied by 100)
 #define RELAY_COOLDOWN_T 500
 // timeout to switch from external to internal temperature data (in milliseconds)
 #define SWITCH_TO_INTERNAL_TIMEOUT 50000
+// interval for updating internal temperature
+#define T_UPDATE_INTERVAL 500
+// interval for updating external t
+#define EXTERNAL_UPDATE_INTERVAL 1000
 
+//////////////////////////
 // modbus consts and works
 #define TCP_PORT 15000
 
@@ -52,7 +54,7 @@ DHT dht(DHTPIN, DHTTYPE);
 #define REGISTER_TARGET_T 5
 // temperature from internal sensor
 #define REGISTER_INTERNAL_T 6
-// temperatur from external sensor (received via modbus-tcp)
+// temperature from external sensor (received via modbus-tcp)
 #define REGISTER_EXTERNAL_T 7
 
 // critical relay temp (degrees multiplied by 100)
@@ -72,21 +74,35 @@ int target_t = 0;
 int internal_t = 0;
 int external_t = 0;
 
-void LoadState()
+bool TryLoad(char *filename)
 {
-	File f = LittleFS.open("/target_t.txt", "r");
-	if (!f) return;
+  File f = LittleFS.open(filename, "r");
+	if (!f) return false;
 	String s = f.readStringUntil('\n');
 	target_t = atoi(s.c_str());
+  f.close();
+  if (target_t == 0) return false;
+	return true;
+}
+
+void LoadState()
+{
+  if (TryLoad("/target_t.txt")) return;
+  TryLoad("/target_t.txt.bak");
+}
+
+void SaveTo(char *filename)
+{
+  File f = LittleFS.open(filename, "w");
+	if (!f) return;
+	f.println(target_t);
 	f.close();
 }
 
 void SaveState()
 {
-	File f = LittleFS.open("/target_t.txt", "w");
-	if (!f) return;
-	f.println(target_t);
-	f.close();
+  SaveTo("/target_t.txt");
+	SaveTo("/target_t.txt.bak");
 }
 
 void setup() 
diff --git a/heater_v3.items b/heater_v3.items
index 6a3112e..bc1e771 100644
--- a/heater_v3.items
+++ b/heater_v3.items
@@ -1,4 +1,4 @@
-Number HEATER_NAME_Mode "HEATER_NAME mode" <switch> {channel="modbus:data:HEATER_NAME:H:HEATER_NAME_Mode:number"}
+Switch HEATER_NAME_Mode "HEATER_NAME mode" <switch> {channel="modbus:data:HEATER_NAME:H:HEATER_NAME_Mode:switch"}
 Switch HEATER_NAME_State "HEATER_NAME state" <switch> {channel="modbus:data:HEATER_NAME:H:HEATER_NAME_State:switch"}
 Number HEATER_NAME_RelayT "HEATER_NAME relay temperature [%.1f °C]" <temperature> {channel="modbus:data:HEATER_NAME:H:HEATER_NAME_RelayT:number"}
 Number HEATER_NAME_Overheat "HEATER_NAME relay overheated" <switch> {channel="modbus:data:HEATER_NAME:H:HEATER_NAME_Overheat:number"}