Recognise community boilers as a heat-network system 🟩

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

domain/epc/property_overlays/main_heating_system_overlay.py

@@ -144,6 +144,11 @@ _MAIN_HEATING_CODES: dict[str, int] = {
     # cases", default SPF 2.30). Modellable without a PCDB index; an actual
     # product index would refine it (ADR-0041).
     "Air source heat pump": 211,
+    # Boiler-driven community / heat-network heating — SAP Table 4a 301. The
+    # calculator derives the heat-source efficiency (80%) + DLF (1.50 default)
+    # from the code (cert_to_inputs). A generic "Community heating" with no named
+    # source stays unmapped (-> None) — the source can't be assumed (ADR-0041).
+    "Community heating, boilers": 301,
 }
 
 

domain/epc/property_overrides/main_heating_system_type.py

@@ -27,4 +27,5 @@ class MainHeatingSystemType(Enum):
     ELECTRIC_ROOM_HEATERS = "Electric room heaters"
     SOLID_FUEL_ROOM_HEATER_CLOSED = "Solid fuel room heater, closed"
     AIR_SOURCE_HEAT_PUMP = "Air source heat pump"
+    COMMUNITY_BOILERS = "Community heating, boilers"
     UNKNOWN = "Unknown"