diff --git a/domain/epc/property_overrides/main_heating_system_type.py b/domain/epc/property_overrides/main_heating_system_type.py
index f8426fdcf..98d07a6e4 100644
--- a/domain/epc/property_overrides/main_heating_system_type.py
+++ b/domain/epc/property_overrides/main_heating_system_type.py
@@ -19,6 +19,15 @@ class MainHeatingSystemType(Enum):
     GAS_COMBI = "Gas boiler, combi"
     GAS_REGULAR = "Gas boiler, regular"
     GAS_CPSU = "Gas CPSU"
+    # Oil / solid-fuel wet boilers off the fuel-agnostic gas default (ADR-0067).
+    # A fuel-blind "Boiler … Regular/Combi" description on a non-gas main_fuel was
+    # funnelled onto the gas archetype; these give it a home, with the fuel column
+    # (`resolve_boiler_archetype`) re-pointing at resolution. Solid fuel is a single
+    # conservative member (SAP 151, 0.60); sub-fuels deferred. Lock-step with
+    # assessment-model#455 / migration 0279 (ADR-0002).
+    OIL_BOILER_REGULAR = "Oil boiler, regular"
+    OIL_BOILER_COMBI = "Oil boiler, combi"
+    SOLID_FUEL_BOILER = "Solid fuel boiler"
     ELECTRIC_STORAGE_OLD = "Electric storage heaters, old"
     ELECTRIC_STORAGE_SLIMLINE = "Electric storage heaters, slimline"
     ELECTRIC_STORAGE_CONVECTOR = "Electric storage heaters, convector"
diff --git a/tests/domain/epc/test_main_heating_system_overlay.py b/tests/domain/epc/test_main_heating_system_overlay.py
index dc50dd2d5..40be0a988 100644
--- a/tests/domain/epc/test_main_heating_system_overlay.py
+++ b/tests/domain/epc/test_main_heating_system_overlay.py
@@ -817,6 +817,116 @@ def test_every_resolvable_main_heating_value_decodes(
     assert simulation is not None
 
 
+@pytest.mark.parametrize(
+    ("main_heating_value", "code"),
+    [
+        # Oil / solid-fuel wet boilers off the fuel-agnostic gas default (ADR-0067).
+        # Modern/condensing codes (A-G deferred, like gas): SAP Table 4b 127
+        # condensing oil regular, 130 condensing oil combi; Table 4a 151 manual-feed
+        # independent solid-fuel boiler (the conservative single member).
+        ("Oil boiler, regular", 127),
+        ("Oil boiler, combi", 130),
+        ("Solid fuel boiler", 151),
+    ],
+)
+def test_oil_and_solid_fuel_boilers_decode_to_their_boiler_codes(
+    main_heating_value: str, code: int
+) -> None:
+    # Act
+    simulation = main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert — its own boiler code, not the mains-gas default.
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.sap_main_heating_code == code
+
+
+@pytest.mark.parametrize(
+    ("main_heating_value", "fuel"),
+    [
+        ("Oil boiler, regular", 28),  # heating oil
+        ("Oil boiler, combi", 28),
+        ("Solid fuel boiler", 33),  # house coal — the conservative solid default
+    ],
+)
+def test_oil_and_solid_fuel_boilers_drag_their_natural_fuel(
+    main_heating_value: str, fuel: int
+) -> None:
+    # The archetype implies a fuel so a system-only override is self-coherent; the
+    # property's `main_fuel` override still wins by last-wins composition (ADR-0041).
+
+    # Act
+    simulation = main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.main_fuel_type == fuel
+
+
+@pytest.mark.parametrize(
+    "main_heating_value", ["Oil boiler, regular", "Oil boiler, combi", "Solid fuel boiler"]
+)
+def test_fuel_boilers_drag_the_gas_pattern_boiler_companions(
+    main_heating_value: str,
+) -> None:
+    # Modelled on the gas boiler (ADR-0067): SAP Table 4a category 2, full modern
+    # controls (Table 4e 2106), a single-rate meter — but NOT a forced gas
+    # connection (an oil/solid boiler needs no gas main, so it inherits the lodged
+    # EPC: `gas_connection_available` stays unset).
+
+    # Act
+    simulation = main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.main_heating_category == 2
+    assert simulation.heating.main_heating_control == 2106
+    assert simulation.heating.meter_type == "Single"
+    assert simulation.heating.gas_connection_available is None
+
+
+@pytest.mark.parametrize(
+    ("main_heating_value", "has_cylinder"),
+    [
+        ("Oil boiler, regular", True),
+        ("Oil boiler, combi", False),  # a combi heats hot water instantaneously
+        ("Solid fuel boiler", True),  # no solid-fuel combi exists
+    ],
+)
+def test_fuel_boiler_cylinder_follows_combi(
+    main_heating_value: str, has_cylinder: bool
+) -> None:
+    # Act
+    simulation = main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert — hot water from the main system, with a cylinder unless a combi.
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.has_hot_water_cylinder is has_cylinder
+
+
+@pytest.mark.parametrize(
+    ("main_heating_value", "fan_flue"),
+    [
+        ("Oil boiler, regular", True),  # modern condensing oil: room-sealed/fan flue
+        ("Oil boiler, combi", True),
+        ("Solid fuel boiler", False),  # solid fuel: conventional (non-fanned) flue
+    ],
+)
+def test_fuel_boiler_fan_flue_follows_fuel(
+    main_heating_value: str, fan_flue: bool
+) -> None:
+    # Act
+    simulation = main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.fan_flue_present is fan_flue
+
+
 def test_solid_fuel_room_heater_decodes_to_the_closed_room_heater_code() -> None:
     # A landlord-named solid-fuel room heater (e.g. a closed stove) is a
     # recognised archetype, not a gas wet system — it must decode to its SAP