diff --git a/domain/epc/property_overlays/main_heating_system_overlay.py b/domain/epc/property_overlays/main_heating_system_overlay.py
index 630c247a4..5d61cb5a8 100644
--- a/domain/epc/property_overlays/main_heating_system_overlay.py
+++ b/domain/epc/property_overlays/main_heating_system_overlay.py
@@ -27,6 +27,10 @@ from domain.modelling.simulation import EpcSimulation, HeatingOverlay
 # 404 fan storage heaters, 191 direct-acting electric boiler.
 _MAIN_HEATING_CODES: dict[str, int] = {
     "Gas boiler, combi": 104,
+    "Gas boiler, regular": 102,
+    "Gas CPSU": 120,
+    "Electric storage heaters, fan": 404,
+    "Direct-acting electric": 191,
 }