diff --git a/Puffer_Speicher/module.php b/Puffer_Speicher/module.php
index 060f088..00c4fd8 100644
--- a/Puffer_Speicher/module.php
+++ b/Puffer_Speicher/module.php
@@ -195,6 +195,7 @@ class Puffer_Speicher extends IPSModule
             }*/
         
             // PT
+            $boilerTemp = $this->GetValue("Boilertemperatur");
             $time_constant= $this->ReadPropertyInteger("ZeitKonstante");
             $delta_t = 5; // Zeitdifferenz zwischen den Messungen (30 Sekunden)
             $alpha = $delta_t / ($time_constant + $delta_t);