diff --git a/data/settings.html b/data/settings.html
index ddcdf82..a70c009 100644
--- a/data/settings.html
+++ b/data/settings.html
@@ -62,6 +62,18 @@
 
         <div id="opentherm-settings-busy" aria-busy="true"></div>
         <form action="/api/settings" id="opentherm-settings" class="hidden">
+          <fieldset>
+            <legend>Unit system</legend>
+            <label>
+              <input type="radio" class="opentherm-unit-system" name="opentherm[unitSystem]" value="0" />
+              Metric (celsius)
+            </label>
+            <label>
+              <input type="radio" class="opentherm-unit-system" name="opentherm[unitSystem]" value="1" />
+              Imperial (fahrenheit)
+            </label>
+          </fieldset>
+
           <div class="grid">
             <label for="opentherm-in-gpio">
               In GPIO
@@ -298,6 +310,18 @@
 
         <div id="system-settings-busy" aria-busy="true"></div>
         <form action="/api/settings" id="system-settings" class="hidden">
+          <fieldset>
+            <legend>Unit system</legend>
+            <label>
+              <input type="radio" class="system-unit-system" name="system[unitSystem]" value="0" />
+              Metric (celsius)
+            </label>
+            <label>
+              <input type="radio" class="system-unit-system" name="system[unitSystem]" value="1" />
+              Imperial (fahrenheit)
+            </label>
+          </fieldset>
+
           <fieldset>
             <label for="system-debug">
               <input type="checkbox" class="system-debug" name="system[debug]" value="true">
diff --git a/lib/HomeAssistantHelper/strings.h b/lib/HomeAssistantHelper/strings.h
index 7811a19..d0ad108c 100644
--- a/lib/HomeAssistantHelper/strings.h
+++ b/lib/HomeAssistantHelper/strings.h
@@ -33,6 +33,8 @@ const char HA_AVAILABILITY_MODE[]               PROGMEM = "availability_mode";
 const char HA_TOPIC[]                           PROGMEM = "topic";
 const char HA_DEVICE_CLASS[]                    PROGMEM = "device_class";
 const char HA_UNIT_OF_MEASUREMENT[]             PROGMEM = "unit_of_measurement";
+const char HA_UNIT_OF_MEASUREMENT_C[]           PROGMEM = "°C";
+const char HA_UNIT_OF_MEASUREMENT_F[]           PROGMEM = "°F";
 const char HA_ICON[]                            PROGMEM = "icon";
 const char HA_MIN[]                             PROGMEM = "min";
 const char HA_MAX[]                             PROGMEM = "max";
diff --git a/src/HaHelper.h b/src/HaHelper.h
index 4a54d38..06f4d97 100644
--- a/src/HaHelper.h
+++ b/src/HaHelper.h
@@ -27,14 +27,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SWITCH), F("emergency")).c_str(), doc);
   }
 
-  bool publishNumberEmergencyTarget(bool enabledByDefault = true) {
+  bool publishNumberEmergencyTarget(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("emergency_target"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("emergency_target"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+    
     doc[FPSTR(HA_NAME)] = F("Emergency target temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-alert");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -142,7 +149,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SWITCH), F("heating_turbo")).c_str(), doc);
   }
 
-  bool publishNumberHeatingTarget(byte minTemp = 20, byte maxTemp = 90, bool enabledByDefault = true) {
+  bool publishNumberHeatingTarget(UnitSystem unit = UnitSystem::METRIC, byte minTemp = 20, byte maxTemp = 90, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
@@ -150,7 +157,14 @@ public:
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("heating_target"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating target");
     doc[FPSTR(HA_ICON)] = F("mdi:radiator");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -167,14 +181,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("heating_target")).c_str(), doc);
   }
 
-  bool publishNumberHeatingHysteresis(bool enabledByDefault = true) {
+  bool publishNumberHeatingHysteresis(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("heating_hysteresis"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("heating_hysteresis"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating hysteresis");
     doc[FPSTR(HA_ICON)] = F("mdi:altimeter");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -191,7 +212,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("heating_hysteresis")).c_str(), doc);
   }
 
-  bool publishSensorHeatingSetpoint(bool enabledByDefault = true) {
+  bool publishSensorHeatingSetpoint(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
@@ -200,7 +221,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating setpoint");
     doc[FPSTR(HA_ICON)] = F("mdi:coolant-temperature");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -211,7 +239,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("heating_setpoint")).c_str(), doc);
   }
 
-  bool publishSensorBoilerHeatingMinTemp(bool enabledByDefault = true) {
+  bool publishSensorBoilerHeatingMinTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -223,7 +251,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Boiler heating min temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-down");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -234,7 +269,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("boiler_heating_min_temp")).c_str(), doc);
   }
 
-  bool publishSensorBoilerHeatingMaxTemp(bool enabledByDefault = true) {
+  bool publishSensorBoilerHeatingMaxTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -246,7 +281,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Boiler heating max temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-up");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -257,14 +299,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("boiler_heating_max_temp")).c_str(), doc);
   }
 
-  bool publishNumberHeatingMinTemp(bool enabledByDefault = true) {
+  bool publishNumberHeatingMinTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("heating_min_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("heating_min_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating min temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-down");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -281,14 +330,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("heating_min_temp")).c_str(), doc);
   }
 
-  bool publishNumberHeatingMaxTemp(bool enabledByDefault = true) {
+  bool publishNumberHeatingMaxTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("heating_max_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("heating_max_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating max temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-up");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -352,7 +408,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SWITCH), F("dhw")).c_str(), doc);
   }
 
-  bool publishNumberDhwTarget(byte minTemp = 40, byte maxTemp = 60, bool enabledByDefault = true) {
+  bool publishNumberDhwTarget(UnitSystem unit = UnitSystem::METRIC, byte minTemp = 40, byte maxTemp = 60, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
@@ -360,7 +416,14 @@ public:
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("dhw_target"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("DHW target");
     doc[FPSTR(HA_ICON)] = F("mdi:water-pump");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -377,7 +440,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("dhw_target")).c_str(), doc);
   }
 
-  bool publishSensorBoilerDhwMinTemp(bool enabledByDefault = true) {
+  bool publishSensorBoilerDhwMinTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -389,7 +452,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Boiler DHW min temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-down");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -400,7 +470,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("boiler_dhw_min_temp")).c_str(), doc);
   }
 
-  bool publishSensorBoilerDhwMaxTemp(bool enabledByDefault = true) {
+  bool publishSensorBoilerDhwMaxTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -412,7 +482,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Boiler DHW max temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-up");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -423,14 +500,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("boiler_dhw_max_temp")).c_str(), doc);
   }
 
-  bool publishNumberDhwMinTemp(bool enabledByDefault = true) {
+  bool publishNumberDhwMinTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("dhw_min_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("dhw_min_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("DHW min temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-down");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -447,14 +531,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("dhw_min_temp")).c_str(), doc);
   }
 
-  bool publishNumberDhwMaxTemp(bool enabledByDefault = true) {
+  bool publishNumberDhwMaxTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("dhw_max_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("dhw_max_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("DHW max temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-up");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -579,14 +670,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("pid_dt")).c_str(), doc);
   }
 
-  bool publishNumberPidMinTemp(bool enabledByDefault = true) {
+  bool publishNumberPidMinTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("pid_min_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("pid_min_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("PID min temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-down");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -603,14 +701,21 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("pid_min_temp")).c_str(), doc);
   }
 
-  bool publishNumberPidMaxTemp(bool enabledByDefault = true) {
+  bool publishNumberPidMaxTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("pid_max_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("pid_max_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("PID max temp");
     doc[FPSTR(HA_ICON)] = F("mdi:thermometer-chevron-up");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("settings"));
@@ -1027,13 +1132,20 @@ public:
   }
 
 
-  bool publishNumberIndoorTemp(bool enabledByDefault = true) {
+  bool publishNumberIndoorTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("indoor_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("indoor_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Indoor temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:home-thermometer");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1050,7 +1162,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("indoor_temp")).c_str(), doc);
   }
 
-  bool publishSensorIndoorTemp(bool enabledByDefault = true) {
+  bool publishSensorIndoorTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
@@ -1059,7 +1171,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Indoor temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:home-thermometer");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1070,13 +1189,20 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("indoor_temp")).c_str(), doc);
   }
 
-  bool publishNumberOutdoorTemp(bool enabledByDefault = true) {
+  bool publishNumberOutdoorTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
     doc[FPSTR(HA_UNIQUE_ID)] = this->getObjectId(F("outdoor_temp"));
     doc[FPSTR(HA_OBJECT_ID)] = this->getObjectId(F("outdoor_temp"));
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("config");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Outdoor temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:home-thermometer-outline");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1093,7 +1219,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_NUMBER), F("outdoor_temp")).c_str(), doc);
   }
 
-  bool publishSensorOutdoorTemp(bool enabledByDefault = true) {
+  bool publishSensorOutdoorTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_ENABLED_BY_DEFAULT)] = enabledByDefault;
@@ -1102,7 +1228,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Outdoor temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:home-thermometer-outline");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1113,7 +1246,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("outdoor_temp")).c_str(), doc);
   }
 
-  bool publishSensorHeatingTemp(bool enabledByDefault = true) {
+  bool publishSensorHeatingTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1125,7 +1258,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("Heating temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:radiator");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1136,7 +1276,7 @@ public:
     return this->publish(this->getTopic(FPSTR(HA_ENTITY_SENSOR), F("heating_temp")).c_str(), doc);
   }
 
-  bool publishSensorDhwTemp(bool enabledByDefault = true) {
+  bool publishSensorDhwTemp(UnitSystem unit = UnitSystem::METRIC, bool enabledByDefault = true) {
     JsonDocument doc;
     doc[FPSTR(HA_AVAILABILITY)][0][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("status"));
     doc[FPSTR(HA_AVAILABILITY)][1][FPSTR(HA_TOPIC)] = this->getDeviceTopic(F("state"));
@@ -1148,7 +1288,14 @@ public:
     doc[FPSTR(HA_ENTITY_CATEGORY)] = F("diagnostic");
     doc[FPSTR(HA_DEVICE_CLASS)] = F("temperature");
     doc[FPSTR(HA_STATE_CLASS)] = F("measurement");
-    doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = F("°C");
+
+    if (unit == UnitSystem::METRIC) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_C);
+      
+    } else if (unit == UnitSystem::IMPERIAL) {
+      doc[FPSTR(HA_UNIT_OF_MEASUREMENT)] = FPSTR(HA_UNIT_OF_MEASUREMENT_F);
+    }
+
     doc[FPSTR(HA_NAME)] = F("DHW temperature");
     doc[FPSTR(HA_ICON)] = F("mdi:water-pump");
     doc[FPSTR(HA_STATE_TOPIC)] = this->getDeviceTopic(F("state"));
diff --git a/src/MqttTask.h b/src/MqttTask.h
index 0b7f5d9..c7d4531 100644
--- a/src/MqttTask.h
+++ b/src/MqttTask.h
@@ -326,11 +326,11 @@ protected:
     this->haHelper->publishSwitchHeating(false);
     this->haHelper->publishSwitchHeatingTurbo();
     this->haHelper->publishNumberHeatingHysteresis();
-    this->haHelper->publishSensorHeatingSetpoint(false);
-    this->haHelper->publishSensorBoilerHeatingMinTemp(false);
-    this->haHelper->publishSensorBoilerHeatingMaxTemp(false);
-    this->haHelper->publishNumberHeatingMinTemp(false);
-    this->haHelper->publishNumberHeatingMaxTemp(false);
+    this->haHelper->publishSensorHeatingSetpoint(settings.system.unitSystem, false);
+    this->haHelper->publishSensorBoilerHeatingMinTemp(settings.system.unitSystem, false);
+    this->haHelper->publishSensorBoilerHeatingMaxTemp(settings.system.unitSystem, false);
+    this->haHelper->publishNumberHeatingMinTemp(settings.system.unitSystem, false);
+    this->haHelper->publishNumberHeatingMaxTemp(settings.system.unitSystem, false);
     this->haHelper->publishNumberHeatingMaxModulation(false);
 
     // pid
@@ -339,8 +339,8 @@ protected:
     this->haHelper->publishNumberPidFactorI();
     this->haHelper->publishNumberPidFactorD();
     this->haHelper->publishNumberPidDt(false);
-    this->haHelper->publishNumberPidMinTemp(false);
-    this->haHelper->publishNumberPidMaxTemp(false);
+    this->haHelper->publishNumberPidMinTemp(settings.system.unitSystem, false);
+    this->haHelper->publishNumberPidMaxTemp(settings.system.unitSystem, false);
 
     // equitherm
     this->haHelper->publishSwitchEquitherm();
@@ -383,20 +383,33 @@ protected:
 
     bool published = false;
     bool isStupidMode = !settings.pid.enable && !settings.equitherm.enable;
-    byte heatingMinTemp = isStupidMode ? settings.heating.minTemp : 10;
-    byte heatingMaxTemp = isStupidMode ? settings.heating.maxTemp : 30;
+    byte heatingMinTemp = 0;
+    byte heatingMaxTemp = 90;
     bool editableOutdoorTemp = settings.sensors.outdoor.type == SensorType::MANUAL;
     bool editableIndoorTemp = settings.sensors.indoor.type == SensorType::MANUAL;
 
+    if (isStupidMode) {
+      heatingMinTemp = settings.heating.minTemp;
+      heatingMaxTemp = settings.heating.maxTemp;
+
+    } else if (settings.system.unitSystem == UnitSystem::METRIC) {
+      heatingMinTemp = 5;
+      heatingMaxTemp = 30;
+
+    } else if (settings.system.unitSystem == UnitSystem::IMPERIAL) {
+      heatingMinTemp = 41;
+      heatingMaxTemp = 86;
+    }
+
     if (force || _dhwPresent != settings.opentherm.dhwPresent) {
       _dhwPresent = settings.opentherm.dhwPresent;
 
       if (_dhwPresent) {
         this->haHelper->publishSwitchDhw(false);
-        this->haHelper->publishSensorBoilerDhwMinTemp(false);
-        this->haHelper->publishSensorBoilerDhwMaxTemp(false);
-        this->haHelper->publishNumberDhwMinTemp(false);
-        this->haHelper->publishNumberDhwMaxTemp(false);
+        this->haHelper->publishSensorBoilerDhwMinTemp(settings.system.unitSystem, false);
+        this->haHelper->publishSensorBoilerDhwMaxTemp(settings.system.unitSystem, false);
+        this->haHelper->publishNumberDhwMinTemp(settings.system.unitSystem, false);
+        this->haHelper->publishNumberDhwMaxTemp(settings.system.unitSystem, false);
         this->haHelper->publishBinSensorDhw();
         this->haHelper->publishSensorDhwTemp();
         this->haHelper->publishSensorDhwFlowRate(false);
@@ -426,7 +439,7 @@ protected:
       _heatingMaxTemp = heatingMaxTemp;
       _isStupidMode = isStupidMode;
 
-      this->haHelper->publishNumberHeatingTarget(heatingMinTemp, heatingMaxTemp, false);
+      this->haHelper->publishNumberHeatingTarget(settings.system.unitSystem, heatingMinTemp, heatingMaxTemp, false);
       this->haHelper->publishClimateHeating(
         heatingMinTemp,
         heatingMaxTemp,
@@ -450,7 +463,7 @@ protected:
       _dhwMinTemp = settings.dhw.minTemp;
       _dhwMaxTemp = settings.dhw.maxTemp;
 
-      this->haHelper->publishNumberDhwTarget(settings.dhw.minTemp, settings.dhw.maxTemp, false);
+      this->haHelper->publishNumberDhwTarget(settings.system.unitSystem, settings.dhw.minTemp, settings.dhw.maxTemp, false);
       this->haHelper->publishClimateDhw(settings.dhw.minTemp, settings.dhw.maxTemp);
 
       published = true;
diff --git a/src/OpenThermTask.h b/src/OpenThermTask.h
index f24a19e..573f99b 100644
--- a/src/OpenThermTask.h
+++ b/src/OpenThermTask.h
@@ -325,7 +325,7 @@ protected:
 
     // Update DHW temp
     byte newDhwTemp = settings.dhw.target;
-    if (settings.opentherm.dhwPresent && settings.dhw.enable && (needSetDhwTemp() || newDhwTemp != currentDhwTemp)) {
+    if (settings.opentherm.dhwPresent && settings.dhw.enable && (this->needSetDhwTemp() || newDhwTemp != currentDhwTemp)) {
       if (newDhwTemp < settings.dhw.minTemp || newDhwTemp > settings.dhw.maxTemp) {
         newDhwTemp = constrain(newDhwTemp, settings.dhw.minTemp, settings.dhw.maxTemp);
       }
@@ -333,7 +333,7 @@ protected:
       Log.sinfoln(FPSTR(L_OT_DHW), F("Set temp = %u"), newDhwTemp);
 
       // Set DHW temp
-      if (this->instance->setDhwTemp(newDhwTemp)) {
+      if (this->instance->setDhwTemp(tempTo(newDhwTemp))) {
         currentDhwTemp = newDhwTemp;
         this->dhwSetTempTime = millis();
 
@@ -343,7 +343,7 @@ protected:
 
       // Set DHW temp to CH2
       if (settings.opentherm.dhwToCh2) {
-        if (!this->instance->setHeatingCh2Temp(newDhwTemp)) {
+        if (!this->instance->setHeatingCh2Temp(tempTo(newDhwTemp))) {
           Log.swarningln(FPSTR(L_OT_DHW), F("Failed set ch2 temp"));
         }
       }
@@ -351,11 +351,11 @@ protected:
 
 
     // Update heating temp
-    if (heatingEnabled && (needSetHeatingTemp() || fabs(vars.parameters.heatingSetpoint - currentHeatingTemp) > 0.0001)) {
+    if (heatingEnabled && (this->needSetHeatingTemp() || fabs(vars.parameters.heatingSetpoint - currentHeatingTemp) > 0.0001)) {
       Log.sinfoln(FPSTR(L_OT_HEATING), F("Set temp = %u"), vars.parameters.heatingSetpoint);
 
       // Set heating temp
-      if (this->instance->setHeatingCh1Temp(vars.parameters.heatingSetpoint)) {
+      if (this->instance->setHeatingCh1Temp(tempTo(vars.parameters.heatingSetpoint))) {
         currentHeatingTemp = vars.parameters.heatingSetpoint;
         this->heatingSetTempTime = millis();
 
@@ -365,7 +365,7 @@ protected:
 
       // Set heating temp to CH2
       if (settings.opentherm.heatingCh1ToCh2) {
-        if (!this->instance->setHeatingCh2Temp(vars.parameters.heatingSetpoint)) {
+        if (!this->instance->setHeatingCh2Temp(tempTo(vars.parameters.heatingSetpoint))) {
           Log.swarningln(FPSTR(L_OT_HEATING), F("Failed set ch2 temp"));
         }
       }
@@ -390,7 +390,7 @@ protected:
 
   void initialize() {
     // Not all boilers support these, only try once when the boiler becomes connected
-    if (updateSlaveVersion()) {
+    if (this->updateSlaveVersion()) {
       Log.straceln(FPSTR(L_OT), F("Slave version: %u, type: %u"), vars.parameters.slaveVersion, vars.parameters.slaveType);
 
     } else {
@@ -398,21 +398,21 @@ protected:
     }
 
     // 0x013F
-    if (setMasterVersion(0x3F, 0x01)) {
+    if (this->setMasterVersion(0x3F, 0x01)) {
       Log.straceln(FPSTR(L_OT), F("Master version: %u, type: %u"), vars.parameters.masterVersion, vars.parameters.masterType);
       
     } else {
       Log.swarningln(FPSTR(L_OT), F("Set master version failed"));
     }
 
-    if (updateSlaveConfig()) {
+    if (this->updateSlaveConfig()) {
       Log.straceln(FPSTR(L_OT), F("Slave member id: %u, flags: %u"), vars.parameters.slaveMemberId, vars.parameters.slaveFlags);
 
     } else {
       Log.swarningln(FPSTR(L_OT), F("Get slave config failed"));
     }
 
-    if (setMasterConfig(settings.opentherm.memberIdCode & 0xFF, (settings.opentherm.memberIdCode & 0xFFFF) >> 8)) {
+    if (this->setMasterConfig(settings.opentherm.memberIdCode & 0xFF, (settings.opentherm.memberIdCode & 0xFFFF) >> 8)) {
       Log.straceln(FPSTR(L_OT), F("Master member id: %u, flags: %u"), vars.parameters.masterMemberId, vars.parameters.masterFlags);
       
     } else {
@@ -598,8 +598,8 @@ protected:
     byte maxTemp = (response & 0xFFFF) >> 8;
 
     if (minTemp >= 0 && maxTemp > 0 && maxTemp > minTemp) {
-      vars.parameters.dhwMinTemp = minTemp;
-      vars.parameters.dhwMaxTemp = maxTemp;
+      vars.parameters.dhwMinTemp = tempFrom(minTemp);
+      vars.parameters.dhwMaxTemp = tempFrom(maxTemp);
 
       return true;
     }
@@ -622,8 +622,8 @@ protected:
     byte maxTemp = (response & 0xFFFF) >> 8;
 
     if (minTemp >= 0 && maxTemp > 0 && maxTemp > minTemp) {
-      vars.parameters.heatingMinTemp = minTemp;
-      vars.parameters.heatingMaxTemp = maxTemp;
+      vars.parameters.heatingMinTemp = tempFrom(minTemp);
+      vars.parameters.heatingMaxTemp = tempFrom(maxTemp);
       return true;
     }
 
@@ -634,7 +634,7 @@ protected:
     unsigned long response = this->instance->sendRequest(CustomOpenTherm::buildRequest(
       OpenThermMessageType::WRITE_DATA,
       OpenThermMessageID::MaxTSet,
-      CustomOpenTherm::temperatureToData(value)
+      CustomOpenTherm::temperatureToData(tempTo(value))
     ));
 
     return CustomOpenTherm::isValidResponse(response);
@@ -650,8 +650,10 @@ protected:
     if (!CustomOpenTherm::isValidResponse(response)) {
       return false;
     }
+    
+    float value = CustomOpenTherm::getFloat(response);
 
-    vars.temperatures.outdoor = CustomOpenTherm::getFloat(response) + settings.sensors.outdoor.offset;
+    vars.temperatures.outdoor = tempFrom(value) + settings.sensors.outdoor.offset;
     return true;
   }
 
@@ -671,7 +673,7 @@ protected:
       return false;
     }
 
-    vars.temperatures.heating = value;
+    vars.temperatures.heating = tempFrom(value);
     return true;
   }
 
@@ -692,7 +694,7 @@ protected:
       return false;
     }
 
-    vars.temperatures.dhw = value;
+    vars.temperatures.dhw = tempFrom(value);
     return true;
   }
 
@@ -771,4 +773,26 @@ protected:
 
     return true;
   }
+
+  static float tempTo(float value) {
+    if (settings.system.unitSystem == UnitSystem::METRIC && settings.opentherm.unitSystem == UnitSystem::IMPERIAL) {
+      value = c2f(value);
+      
+    } else if (settings.system.unitSystem == UnitSystem::IMPERIAL && settings.opentherm.unitSystem == UnitSystem::METRIC) {
+      value = f2c(value);
+    }
+
+    return value;
+  }
+
+  static float tempFrom(float value) {
+    if (settings.system.unitSystem == UnitSystem::METRIC && settings.opentherm.unitSystem == UnitSystem::IMPERIAL) {
+      value = f2c(value);
+      
+    } else if (settings.system.unitSystem == UnitSystem::IMPERIAL && settings.opentherm.unitSystem == UnitSystem::METRIC) {
+      value = c2f(value);
+    }
+
+    return value;
+  }
 };
diff --git a/src/RegulatorTask.h b/src/RegulatorTask.h
index df18016..b6d9c84 100644
--- a/src/RegulatorTask.h
+++ b/src/RegulatorTask.h
@@ -69,7 +69,7 @@ protected:
       }
     }
 
-    // Ограничиваем, если до этого не ограничило
+    // Limits
     if (newTemp < settings.heating.minTemp || newTemp > settings.heating.maxTemp) {
       newTemp = constrain(newTemp, settings.heating.minTemp, settings.heating.maxTemp);
     }
@@ -182,7 +182,6 @@ protected:
     }
 
     newTemp = round(newTemp);
-    newTemp = constrain(newTemp, 0, 100);
     return newTemp;
   }
 
@@ -273,16 +272,36 @@ protected:
     }
   }
 
+  /**
+   * @brief Get the Equitherm Temp
+   * Calculations in degrees C, conversion occurs when using F
+   * 
+   * @param minTemp 
+   * @param maxTemp 
+   * @return float 
+   */
   float getEquithermTemp(int minTemp, int maxTemp) {
+    float targetTemp = vars.states.emergency ? settings.emergency.target : settings.heating.target;
+    float indoorTemp = vars.temperatures.indoor;
+    float outdoorTemp = vars.temperatures.outdoor;
+
+    if (settings.system.unitSystem == UnitSystem::IMPERIAL) {
+      minTemp = f2c(minTemp);
+      maxTemp = f2c(maxTemp);
+      targetTemp = f2c(targetTemp);
+      indoorTemp = f2c(indoorTemp);
+      outdoorTemp = f2c(outdoorTemp);
+    }
+
     if (vars.states.emergency) {
       etRegulator.Kt = 0;
       etRegulator.indoorTemp = 0;
-      etRegulator.outdoorTemp = vars.temperatures.outdoor;
+      etRegulator.outdoorTemp = outdoorTemp;
 
     } else if (settings.pid.enable) {
       etRegulator.Kt = 0;
-      etRegulator.indoorTemp = round(vars.temperatures.indoor);
-      etRegulator.outdoorTemp = round(vars.temperatures.outdoor);
+      etRegulator.indoorTemp = round(indoorTemp);
+      etRegulator.outdoorTemp = round(outdoorTemp);
 
     } else {
       if (settings.heating.turbo) {
@@ -290,17 +309,21 @@ protected:
       } else {
         etRegulator.Kt = settings.equitherm.t_factor;
       }
-      etRegulator.indoorTemp = vars.temperatures.indoor;
-      etRegulator.outdoorTemp = vars.temperatures.outdoor;
+      etRegulator.indoorTemp = indoorTemp;
+      etRegulator.outdoorTemp = outdoorTemp;
     }
 
     etRegulator.setLimits(minTemp, maxTemp);
     etRegulator.Kn = settings.equitherm.n_factor;
-    // etRegulator.Kn = tuneEquithermN(etRegulator.Kn, vars.temperatures.indoor, settings.heating.target, 300, 1800, 0.01, 1);
     etRegulator.Kk = settings.equitherm.k_factor;
-    etRegulator.targetTemp = vars.states.emergency ? settings.emergency.target : settings.heating.target;
+    etRegulator.targetTemp = targetTemp;
+    float result = etRegulator.getResult();
 
-    return etRegulator.getResult();
+    if (settings.system.unitSystem == UnitSystem::IMPERIAL) {
+      result = c2f(result);
+    }
+
+    return result;
   }
 
   float getPidTemp(int minTemp, int maxTemp) {
diff --git a/src/SensorsTask.h b/src/SensorsTask.h
index b0ea500..bea4ce9 100644
--- a/src/SensorsTask.h
+++ b/src/SensorsTask.h
@@ -79,14 +79,34 @@ protected:
     }
     #endif
 
-    if (outdoorTempUpdated && fabs(vars.temperatures.outdoor - this->filteredOutdoorTemp) > 0.099) {
-      vars.temperatures.outdoor = this->filteredOutdoorTemp + settings.sensors.outdoor.offset;
-      Log.sinfoln(FPSTR(L_SENSORS_OUTDOOR), F("New temp: %f"), vars.temperatures.outdoor);
+    if (outdoorTempUpdated) {
+      float newTemp = settings.sensors.outdoor.offset;
+      if (settings.system.unitSystem == UnitSystem::METRIC) {
+        newTemp += this->filteredOutdoorTemp;
+
+      } else if (settings.system.unitSystem == UnitSystem::IMPERIAL) {
+        newTemp += c2f(this->filteredOutdoorTemp);
+      }
+
+      if (fabs(vars.temperatures.outdoor - newTemp) > 0.099) {
+        vars.temperatures.outdoor = newTemp;
+        Log.sinfoln(FPSTR(L_SENSORS_OUTDOOR), F("New temp: %f"), vars.temperatures.outdoor);
+      }
     }
 
-    if (indoorTempUpdated && fabs(vars.temperatures.indoor - this->filteredIndoorTemp) > 0.099) {
-      vars.temperatures.indoor = this->filteredIndoorTemp + settings.sensors.indoor.offset;
-      Log.sinfoln(FPSTR(L_SENSORS_INDOOR), F("New temp: %f"), vars.temperatures.indoor);
+    if (indoorTempUpdated) {
+      float newTemp = settings.sensors.indoor.offset;
+      if (settings.system.unitSystem == UnitSystem::METRIC) {
+        newTemp += this->filteredIndoorTemp;
+
+      } else if (settings.system.unitSystem == UnitSystem::IMPERIAL) {
+        newTemp += c2f(this->filteredIndoorTemp);
+      }
+
+      if (fabs(vars.temperatures.indoor - newTemp) > 0.099) {
+        vars.temperatures.indoor = newTemp;
+        Log.sinfoln(FPSTR(L_SENSORS_INDOOR), F("New temp: %f"), vars.temperatures.indoor);
+      }
     }
   }
 
diff --git a/src/Settings.h b/src/Settings.h
index 6576040..32954e5 100644
--- a/src/Settings.h
+++ b/src/Settings.h
@@ -27,6 +27,7 @@ struct Settings {
     bool debug = DEBUG_BY_DEFAULT;
     bool useSerial = USE_SERIAL;
     bool useTelnet = USE_TELNET;
+    UnitSystem unitSystem = UnitSystem::METRIC;
   } system;
 
   struct {
@@ -36,6 +37,7 @@ struct Settings {
   } portal;
 
   struct {
+    UnitSystem unitSystem = UnitSystem::METRIC;
     byte inGpio = DEFAULT_OT_IN_GPIO;
     byte outGpio = DEFAULT_OT_OUT_GPIO;
     unsigned int memberIdCode = 0;
diff --git a/src/defines.h b/src/defines.h
index 14cd74b..420dc47 100644
--- a/src/defines.h
+++ b/src/defines.h
@@ -118,4 +118,9 @@ enum class SensorType : byte {
   BLUETOOTH
 };
 
+enum class UnitSystem : byte {
+  METRIC,
+  IMPERIAL
+};
+
 char buffer[255];
\ No newline at end of file
diff --git a/src/utils.h b/src/utils.h
index c17c6ed..c1c584f 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -1,5 +1,25 @@
 #include <Arduino.h>
 
+inline float c2f(float value) {
+  return (9.0f / 5.0f) * value + 32.0f;
+}
+
+inline float f2c(float value) {
+  return (value - 32.0f) * (5.0f / 9.0f);
+}
+
+bool isValidTemp(float value, UnitSystem unit, float min = 0.1f, float max = 99.9f) {
+  if (unit == UnitSystem::METRIC) {
+    return value >= min && value <= max;
+
+  } else if (unit == UnitSystem::IMPERIAL) {
+    return value >= c2f(min) && value <= c2f(max);
+
+  } else {
+    return false;
+  }
+}
+
 double roundd(double value, uint8_t decimals = 2) {
   if (decimals == 0) {
     return (int)(value + 0.5);
@@ -13,7 +33,7 @@ double roundd(double value, uint8_t decimals = 2) {
   return (int)(value * multiplier) / multiplier;
 }
 
-size_t getTotalHeap() {
+inline size_t getTotalHeap() {
   #if defined(ARDUINO_ARCH_ESP32)
   return ESP.getHeapSize();
   #elif defined(ARDUINO_ARCH_ESP8266)
@@ -63,7 +83,7 @@ size_t getMaxFreeBlockHeap(bool getMinValue = false) {
   return getMinValue ? minValue : value;
 }
 
-uint8_t getHeapFrag() {
+inline uint8_t getHeapFrag() {
   return 100 - getMaxFreeBlockHeap() * 100.0 / getFreeHeap();
 }
 
@@ -268,11 +288,13 @@ void settingsToJson(const Settings& src, JsonVariant dst, bool safe = false) {
     dst["system"]["debug"] = src.system.debug;
     dst["system"]["useSerial"] = src.system.useSerial;
     dst["system"]["useTelnet"] = src.system.useTelnet;
+    dst["system"]["unitSystem"] = static_cast<byte>(src.system.unitSystem);
 
     dst["portal"]["useAuth"] = src.portal.useAuth;
     dst["portal"]["login"] = src.portal.login;
     dst["portal"]["password"] = src.portal.password;
 
+    dst["opentherm"]["unitSystem"] = static_cast<byte>(src.opentherm.unitSystem);
     dst["opentherm"]["inGpio"] = src.opentherm.inGpio;
     dst["opentherm"]["outGpio"] = src.opentherm.outGpio;
     dst["opentherm"]["memberIdCode"] = src.opentherm.memberIdCode;
@@ -377,6 +399,25 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
       changed = true;
     }
 
+    if (!src["system"]["unitSystem"].isNull()) {
+      byte value = src["system"]["unitSystem"].as<unsigned char>();
+
+      switch (value) {
+        case static_cast<byte>(UnitSystem::METRIC):
+          dst.system.unitSystem = UnitSystem::METRIC;
+          changed = true;
+          break;
+
+        case static_cast<byte>(UnitSystem::IMPERIAL):
+          dst.system.unitSystem = UnitSystem::IMPERIAL;
+          changed = true;
+          break;
+
+        default:
+          break;
+      }
+    }
+
 
     // portal
     if (src["portal"]["useAuth"].is<bool>()) {
@@ -404,6 +445,25 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
 
 
     // opentherm
+    if (!src["opentherm"]["unitSystem"].isNull()) {
+      byte value = src["opentherm"]["unitSystem"].as<unsigned char>();
+
+      switch (value) {
+        case static_cast<byte>(UnitSystem::METRIC):
+          dst.opentherm.unitSystem = UnitSystem::METRIC;
+          changed = true;
+          break;
+
+        case static_cast<byte>(UnitSystem::IMPERIAL):
+          dst.opentherm.unitSystem = UnitSystem::IMPERIAL;
+          changed = true;
+          break;
+
+        default:
+          break;
+      }
+    }
+
     if (!src["opentherm"]["inGpio"].isNull()) {
       if (src["opentherm"]["inGpio"].is<JsonString>() && src["opentherm"]["inGpio"].as<JsonString>().size() == 0) {
         if (dst.opentherm.inGpio != GPIO_IS_NOT_CONFIGURED) {
@@ -567,7 +627,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src["emergency"]["target"].isNull()) {
     double value = src["emergency"]["target"].as<double>();
 
-    if (value > 0 && value < 100) {
+    if (isValidTemp(value, dst.system.unitSystem)) {
       dst.emergency.target = roundd(value, 2);
       changed = true;
     }
@@ -618,7 +678,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src["heating"]["target"].isNull()) {
     double value = src["heating"]["target"].as<double>();
 
-    if (value > 0 && value < 100) {
+    if (isValidTemp(value, dst.system.unitSystem)) {
       dst.heating.target = roundd(value, 2);
       changed = true;
     }
@@ -670,7 +730,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src["dhw"]["target"].isNull()) {
     unsigned char value = src["dhw"]["target"].as<unsigned char>();
 
-    if (value >= 0 && value < 100) {
+    if (isValidTemp(value, dst.system.unitSystem)) {
       dst.dhw.target = value;
       changed = true;
     }
@@ -740,7 +800,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src["pid"]["maxTemp"].isNull()) {
     unsigned char value = src["pid"]["maxTemp"].as<unsigned char>();
 
-    if (value > 0 && value <= 100 && value > dst.pid.minTemp) {
+    if (isValidTemp(value, dst.system.unitSystem) && value > dst.pid.minTemp) {
       dst.pid.maxTemp = value;
       changed = true;
     }
@@ -749,7 +809,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src["pid"]["minTemp"].isNull()) {
     unsigned char value = src["pid"]["minTemp"].as<unsigned char>();
 
-    if (value >= 0 && value < 100 && value < dst.pid.maxTemp) {
+    if (isValidTemp(value, dst.system.unitSystem) && value < dst.pid.maxTemp) {
       dst.pid.minTemp = value;
       changed = true;
     }
@@ -1031,7 +1091,7 @@ bool jsonToVars(const JsonVariantConst src, Variables& dst) {
   if (!src["temperatures"]["indoor"].isNull()) {
     double value = src["temperatures"]["indoor"].as<double>();
 
-    if (settings.sensors.indoor.type == SensorType::MANUAL && value > -100 && value < 100) {
+    if (settings.sensors.indoor.type == SensorType::MANUAL && isValidTemp(value, settings.system.unitSystem, -99.9f, 99.9f)) {
       dst.temperatures.indoor = roundd(value, 2);
       changed = true;
     }
@@ -1040,7 +1100,7 @@ bool jsonToVars(const JsonVariantConst src, Variables& dst) {
   if (!src["temperatures"]["outdoor"].isNull()) {
     double value = src["temperatures"]["outdoor"].as<double>();
 
-    if (settings.sensors.outdoor.type == SensorType::MANUAL && value > -100 && value < 100) {
+    if (settings.sensors.outdoor.type == SensorType::MANUAL && isValidTemp(value, settings.system.unitSystem, -99.9f, 99.9f)) {
       dst.temperatures.outdoor = roundd(value, 2);
       changed = true;
     }