map electric storage heater fuel type 🟩

datatypes/epc/domain/mapper.py

@@ -1556,12 +1556,19 @@ def _map_sap_heating(
         else None
     )
 
+    _ELECTRIC_SYSTEM_TYPES = {"electric storage heaters", "electric underfloor heating"}
+    fuel_type = (
+        main.fuel
+        if main.fuel
+        else ("Electricity" if main.system_type.lower() in _ELECTRIC_SYSTEM_TYPES else main.fuel)
+    )
+
     return SapHeating(
         instantaneous_wwhrs=InstantaneousWwhrs(),
         main_heating_details=[
             MainHeatingDetail(
                 has_fghrs=main.flue_gas_heat_recovery_system,
-                main_fuel_type=main.fuel,
+                main_fuel_type=fuel_type,
                 heat_emitter_type=main.emitter,
                 emitter_temperature=main.emitter_temperature,
                 fan_flue_present=main.fan_assist,