diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index 53917b864..862f301af 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -858,3 +858,25 @@ class TestPasHubUnmappedMainFuel:
 
         # Assert
         assert result.sap_heating.main_heating_details[0].main_fuel_type == 30
+
+
+class TestPasHubUnmappedHeatEmitter:
+    """A PasHub survey whose surveyed main-heating emitter label the mapper does
+    not yet cover must strict-raise `UnmappedPasHubLabel` at the boundary,
+    naming the label — so a coverage gap is fixed here (a one-line lookup
+    addition) rather than passed downstream as a raw string to resurface as the
+    calculator's `UnmappedSapCode: heat_emitter_type`.
+    """
+
+    def test_unrecognised_emitter_label_raises_naming_the_label(self) -> None:
+        # Arrange — an example fixture whose emitter cell carries a label the
+        # Elmhurst emitter map does not cover.
+        from datatypes.epc.domain.mapper import UnmappedPasHubLabel
+
+        raw = load("pashub_rdsap_site_notes_example1.json")
+        raw["heating_and_hot_water"]["main_heating"]["emitter"] = "Skirting heaters"
+        survey = from_dict(PasHubRdSapSiteNotes, raw)
+
+        # Act / Assert
+        with pytest.raises(UnmappedPasHubLabel, match="Skirting heaters"):
+            EpcPropertyDataMapper.from_site_notes(survey)