diff --git a/domain/epc_prediction/epc_prediction.py b/domain/epc_prediction/epc_prediction.py
index 4261df6d..072fcfc6 100644
--- a/domain/epc_prediction/epc_prediction.py
+++ b/domain/epc_prediction/epc_prediction.py
@@ -93,7 +93,15 @@ class EpcPrediction:
         electricity tariff (`sap_energy_source.meter_type`) and hot-water flags
         live on loose top-level fields. Carry the donor's whole set, not a subset
         — otherwise a donated storage system lands on the template's single-rate
-        meter and the SAP score collapses (off-peak heat billed at the peak rate)."""
+        meter and the SAP score collapses (off-peak heat billed at the peak rate).
+
+        The system also has a DISPLAY face — the building-passport "Main Heating"
+        and "Heating Control" rows (`main_heating` / `main_heating_controls`
+        EnergyElements). These describe the same system as the calc cluster, so
+        they travel with the donor too; left on the structural template they are
+        incoherent with the donated calc heating, and `main_heating_controls`
+        shows "Unknown" whenever the size-template lodged no control row but the
+        donor does (predicted property 721167, ADR-0029 follow-up)."""
         donor = _heating_donor(comparables.members)
         if donor is None:
             return
@@ -101,6 +109,10 @@ class EpcPrediction:
         predicted.has_hot_water_cylinder = donor.epc.has_hot_water_cylinder
         predicted.solar_water_heating = donor.epc.solar_water_heating
         predicted.sap_energy_source.meter_type = donor.epc.sap_energy_source.meter_type
+        predicted.main_heating = copy.deepcopy(donor.epc.main_heating)
+        predicted.main_heating_controls = copy.deepcopy(
+            donor.epc.main_heating_controls
+        )
 
     @staticmethod
     def _apply_glazing_mode(