diff --git a/tests/domain/epc/test_main_heating_system_overlay.py b/tests/domain/epc/test_main_heating_system_overlay.py
index 27eb6625b..dff74bccf 100644
--- a/tests/domain/epc/test_main_heating_system_overlay.py
+++ b/tests/domain/epc/test_main_heating_system_overlay.py
@@ -74,6 +74,22 @@ def test_electric_room_heaters_overlay_the_room_heater_category() -> None:
     assert simulation.heating.main_heating_category == 10
 
 
+def test_electric_room_heaters_overlay_the_room_heater_charge_control() -> None:
+    # A system-replacing override must stamp its own control, not inherit the
+    # replaced system's. Electric room heaters take the Table 4e Group 6
+    # room-heater control 2601 (+0.3 C, the conservative no-thermostat default,
+    # matching the gas/oil/solid room heaters). Leaving it unset lets a replaced
+    # storage heater's manual charge control 2401 (+0.7 C) survive and over-warm
+    # the modelled dwelling.
+    # Act
+    simulation = main_heating_overlay_for("Electric room heaters", 0)
+
+    # Assert — SAP Table 4e Group 6 room-heater control.
+    assert simulation is not None
+    assert simulation.heating is not None
+    assert simulation.heating.main_heating_control == 2601
+
+
 @pytest.mark.parametrize(
     ("main_heating_value", "code"),
     [