diff --git a/custom_components/bayernluefter/number.py b/custom_components/bayernluefter/number.py
index 7f816b9..4a3a1fd 100644
--- a/custom_components/bayernluefter/number.py
+++ b/custom_components/bayernluefter/number.py
@@ -81,6 +81,14 @@ def __init__(
         super().__init__(coordinator, description)
         self.entity_description = description
 
+    @property
+    def available(self) -> bool:
+        return (
+            super().available
+            and self.entity_description.key in self._device.data
+            and not self._device.data.get("SystemOn", False)
+        )
+
     @property
     def native_value(self) -> float | None:
         """Return the value reported by the sensor."""