diff --git a/backend/Property.py b/backend/Property.py
index 649a9547..f8b40872 100644
--- a/backend/Property.py
+++ b/backend/Property.py
@@ -93,7 +93,7 @@ class Property:
         self.data = {
             k.replace("_", "-"): v for k, v in epc_record.get("prepared_epc").items()
         }
-        
+
         self.old_data = epc_record.get("old_data")
         self.property_dimensions = None
         # This is a list of measures that have already been installed in the property, typically found as a result
@@ -1181,6 +1181,14 @@ class Property:
         self.heating_energy_source = list({
             fuel for key, fuel in heating_fuel_mapping.items() if self.main_heating.get(key, False)
         })
+
+        if set(self.heating_energy_source) == {'Electricity', 'Natural Gas'}:
+            # It means they have mixed heating so we take the primary one, based on main fuel
+            if self.main_fuel["clean_description"] == "Mains gas not community":
+                self.heating_energy_source = ['Natural Gas']
+            else:
+                self.heating_energy_source = ['Electricity']
+
         if len(self.heating_energy_source) == 0 or len(self.heating_energy_source) > 1:
             raise Exception("Investigate me")