diff --git a/src/vaillant/08.hmu.tsp b/src/vaillant/08.hmu.tsp
index ec31e9fb..8ea59e64 100644
--- a/src/vaillant/08.hmu.tsp
+++ b/src/vaillant/08.hmu.tsp
@@ -208,6 +208,12 @@ namespace Hmu {
     value: temp;
   }
 
+  @inherit(r_2)
+  @ext(0x22)
+  model SourceTempInput {
+    value: temp;
+  }
+
   @inherit(r_2)
   @ext(0x27)
   model SourceTempOutput {