diff --git a/fritz_temp_sync/fritzbox.py b/fritz_temp_sync/fritzbox.py
index b1d1b15..fb93355 100755
--- a/fritz_temp_sync/fritzbox.py
+++ b/fritz_temp_sync/fritzbox.py
@@ -11,13 +11,14 @@ import logging
 
 
 class FritzBox:
-    def __init__(self, url: str, password: str, user: str = None) -> None:
+    def __init__(self, url: str, password: str, user: str = None, dry_run: bool = False) -> None:
         self._endpoints = {
             "login": "login_sid.lua?version=2",
             "logout": "index.lua",
             "data": "data.lua"
         }
         self.url: str = url
+        self.dry_run: bool = dry_run
         self.user: Optional[str] = user
         self.session: requests.Session = requests.Session()
         self.password: str = password
@@ -171,6 +172,9 @@ class FritzBox:
         return current_temp, current_offset, device["id"], device["displayName"]
 
     def set_offset(self, current_temp: str, offset: float, device_id: int, device_name: str) -> None:
+        if self.dry_run:
+            logging.warning("No updates in dry-run-mode")
+            return
         data = {
             "xhr": 1,
             "sid": self.sid,
@@ -178,7 +182,7 @@ class FritzBox:
             "device": device_id,
             "page": "home_auto_hkr_edit"
         }
-        r = self.session.post(f"{self.url}/{self._endpoints['data']}", data=data)
+        self.session.post(f"{self.url}/{self._endpoints['data']}", data=data)
 
         data = {
             "xhr": 1,
@@ -207,5 +211,6 @@ class FritzBox:
         if device_name not in self.update_time.keys() or (datetime.now() - self.update_time[device_name]) > delta:
             current_temp, current_offset, idx, name = self.get_device_data(name=device_name)
             new_offset = current_offset + real_temp - current_temp
-            logging.info(f"Should update offset from {current_offset} to {new_offset}")
+            logging.info(f"Update offset from {current_offset} to {new_offset}")
+            self.set_offset(current_temp, new_offset, idx, device_name)
             self.update_time[device_name] = datetime.now()