diff --git a/nibe/data/extensions.json b/nibe/data/extensions.json
index 724f8b9..0cb0445 100644
--- a/nibe/data/extensions.json
+++ b/nibe/data/extensions.json
@@ -37,7 +37,8 @@
           "0": "OFF",
           "1": "ON",
           "2": "BT50",
-          "10": "RMU-BT50"
+          "10": "RMU-BT50",
+          "18": "BT74"
         }
       },
       "43013": {
@@ -480,5 +481,21 @@
         "default": 200
       }
     }
+  },
+  {
+    "description": "Correction for BT71 missing in F1155/F1255",
+    "files": [
+      "f1155_f1255.json"
+    ],
+    "data": {
+      "40152": {
+        "title": "BT71 Ext. Return Temp",
+        "info": "External return temperature, BT71",
+        "unit": "°C",
+        "size": "s16",
+        "factor": 10,
+        "name": "bt71-ext-return-temp-40152"
+      }
+    }
   }
 ]
diff --git a/nibe/data/f1145_f1245.json b/nibe/data/f1145_f1245.json
index 081931f..b8e3dd5 100644
--- a/nibe/data/f1145_f1245.json
+++ b/nibe/data/f1145_f1245.json
@@ -9027,7 +9027,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47341": {
diff --git a/nibe/data/f1155_f1255.json b/nibe/data/f1155_f1255.json
index b0e0c52..f9e5311 100644
--- a/nibe/data/f1155_f1255.json
+++ b/nibe/data/f1155_f1255.json
@@ -425,6 +425,14 @@
     "factor": 10,
     "name": "bt70-hw-comfort-supply-temp-40147"
   },
+  "40152": {
+    "title": "BT71 Ext. Return Temp",
+    "info": "External return temperature, BT71",
+    "unit": "\u00b0C",
+    "size": "s16",
+    "factor": 10,
+    "name": "bt71-ext-return-temp-40152"
+  },
   "40155": {
     "title": "EQ1-BT57 Collector Temp.",
     "info": "External collector temperature, BT57, for ACS",
@@ -4750,7 +4758,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47341": {
diff --git a/nibe/data/f1345.json b/nibe/data/f1345.json
index 06eea30..edf82cd 100644
--- a/nibe/data/f1345.json
+++ b/nibe/data/f1345.json
@@ -9419,7 +9419,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47341": {
diff --git a/nibe/data/f1355.json b/nibe/data/f1355.json
index 0910d25..d00083d 100644
--- a/nibe/data/f1355.json
+++ b/nibe/data/f1355.json
@@ -9578,7 +9578,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47341": {
diff --git a/nibe/data/f370_f470.json b/nibe/data/f370_f470.json
index 2060781..a0ed4d8 100644
--- a/nibe/data/f370_f470.json
+++ b/nibe/data/f370_f470.json
@@ -3072,7 +3072,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47351": {
diff --git a/nibe/data/f730.json b/nibe/data/f730.json
index 518a234..cae273c 100644
--- a/nibe/data/f730.json
+++ b/nibe/data/f730.json
@@ -3552,7 +3552,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47352": {
diff --git a/nibe/data/f750.json b/nibe/data/f750.json
index a4693ac..d5b0186 100644
--- a/nibe/data/f750.json
+++ b/nibe/data/f750.json
@@ -3943,7 +3943,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47352": {
diff --git a/nibe/data/smo20.json b/nibe/data/smo20.json
index 7c6969c..2927eca 100644
--- a/nibe/data/smo20.json
+++ b/nibe/data/smo20.json
@@ -2406,7 +2406,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47343": {
diff --git a/nibe/data/smo40.json b/nibe/data/smo40.json
index dff8d3b..534282e 100644
--- a/nibe/data/smo40.json
+++ b/nibe/data/smo40.json
@@ -7261,7 +7261,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47343": {
diff --git a/nibe/data/vvm225_vvm320_vvm325.json b/nibe/data/vvm225_vvm320_vvm325.json
index 73c706a..f2b1ff0 100644
--- a/nibe/data/vvm225_vvm320_vvm325.json
+++ b/nibe/data/vvm225_vvm320_vvm325.json
@@ -4497,7 +4497,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47343": {
diff --git a/nibe/data/vvm310_vvm500.json b/nibe/data/vvm310_vvm500.json
index 59565e4..1c85072 100644
--- a/nibe/data/vvm310_vvm500.json
+++ b/nibe/data/vvm310_vvm500.json
@@ -4444,7 +4444,8 @@
       "0": "OFF",
       "1": "ON",
       "2": "BT50",
-      "10": "RMU-BT50"
+      "10": "RMU-BT50",
+      "18": "BT74"
     }
   },
   "47343": {