diff --git a/applications/landlord_description_overrides/handler.py b/applications/landlord_description_overrides/handler.py
index dd37e461c..f33dd3705 100644
--- a/applications/landlord_description_overrides/handler.py
+++ b/applications/landlord_description_overrides/handler.py
@@ -13,6 +13,7 @@ from domain.epc.property_overrides.glazing_type import GlazingType
 from domain.epc.property_overrides.glazing_mix_guard import glazing_mix_guard
 from domain.epc.property_overrides.main_fuel_type import MainFuelType
 from domain.epc.property_overrides.main_heating_system_type import MainHeatingSystemType
+from domain.epc.property_overrides.main_heating_guard import main_heating_guard
 from domain.epc.property_overrides.property_type import PropertyType
 from domain.epc.property_overrides.roof_type import RoofType
 from domain.epc.property_overrides.roof_party_ceiling_guard import (
@@ -184,8 +185,15 @@ def _build_columns(
         "main_heating_system": lambda src: ClassifiableColumn(
             name="main_heating_system",
             source_column=src,
-            classifier=ChatGptColumnClassifier(
-                chat_gpt, MainHeatingSystemType, MainHeatingSystemType.UNKNOWN
+            # High heat retention storage heaters have no LLM target distinct from
+            # old storage, so they were funnelled into "Electric storage heaters,
+            # old" (401); the deterministic guard resolves HHRSH to its own
+            # archetype (SAP 409) and the LLM handles the rest (#1376, ADR-0044).
+            classifier=GuardedColumnClassifier(
+                guard=main_heating_guard,
+                fallback=ChatGptColumnClassifier(
+                    chat_gpt, MainHeatingSystemType, MainHeatingSystemType.UNKNOWN
+                ),
             ),
             repo=LandlordOverridesRepository[MainHeatingSystemType](
                 session, LandlordMainHeatingSystemOverrideRow