diff --git a/custom_components/weishaupt_modbus/number.py b/custom_components/weishaupt_modbus/number.py
index 8c2055e..0effcd7 100644
--- a/custom_components/weishaupt_modbus/number.py
+++ b/custom_components/weishaupt_modbus/number.py
@@ -42,6 +42,7 @@ async def async_setup_entry(
             HK_Raum_Soll_Normal(host, port),
             HK_Raum_Soll_Absenk(host, port),
             HK_Heizkennlinie(host, port),
+            HK_SommerWinterUmschaltung(host, port),
         ],
         update_before_add=True,
     )
@@ -398,3 +399,46 @@ def device_info(self) -> DeviceInfo:
         return {
             "identifiers": {(DOMAIN, "Heizkreis")},
         }
+
+
+class HK_SommerWinterUmschaltung(NumberEntity):
+    """Representation of a WEM Portal number."""
+
+    _attr_name = "HK Sommer Winter Umschaltung"
+    _attr_unique_id = DOMAIN + _attr_name
+    _attr_native_value = 0
+    _attr_should_poll = True
+    _attr_native_min_value = 3
+    _attr_native_max_value = 30
+    _attr_native_step = 0.5
+    _attr_native_unit_of_measurement = UnitOfTemperature.CELSIUS
+
+    def __init__(self, host, port) -> None:
+        """Init."""
+        self._host = host
+        self._port = port
+        # whp = wp.heat_pump(host, port)
+        # whp.connect()
+        # self._attr_native_value = whp.WW_Absenk
+        # self.async_write_ha_state()
+
+    async def async_set_native_value(self, value: float) -> None:
+        """Update the current value."""
+        whp = wp.heat_pump(self._host, self._port)
+        whp.connect()
+        whp.HK_SommerWinterUmschaltung = value
+        self._attr_native_value = whp.HK_SommerWinterUmschaltung
+        self.async_write_ha_state()
+
+    async def async_update(self) -> None:
+        """Update Entity Only used by the generic entity update service."""
+        whp = wp.heat_pump(self._host, self._port)
+        whp.connect()
+        self._attr_native_value = whp.HK_SommerWinterUmschaltung
+
+    @property
+    def device_info(self) -> DeviceInfo:
+        """Information about this entity/device."""
+        return {
+            "identifiers": {(DOMAIN, "Heizkreis")},
+        }
diff --git a/custom_components/weishaupt_modbus/wp.py b/custom_components/weishaupt_modbus/wp.py
index 47a0eb0..42a21fa 100644
--- a/custom_components/weishaupt_modbus/wp.py
+++ b/custom_components/weishaupt_modbus/wp.py
@@ -363,6 +363,15 @@ def HK_Heizkennlinie(self):
     def HK_Heizkennlinie(self, value):
         self.WWP.write_register(41108, int(value * 100), slave=1)
 
+    @property
+    def HK_SommerWinterUmschaltung(self):
+        """Test."""
+        return self.WWP.read_holding_registers(41109, slave=1).registers[0] / 10
+
+    @HK_SommerWinterUmschaltung.setter
+    def HK_SommerWinterUmschaltung(self, value):
+        self.WWP.write_register(41109, int(value * 10), slave=1)
+
     #####################
     #   Warm Water      #
     #####################