diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index b8f6a1377..2631a9973 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -1196,6 +1196,10 @@ class TestSecondaryHeatingTypeCoding:
             # the fireplace (no qualifier in the label) — PCDB 601, eff 50%;
             # 602 (with back boiler) rejected, no back-boiler qualifier.
             ("Pre 1980 - Open front fire with open flue", 601),
+            # Room-sealed (balanced flue) gas fire/wall heater — PCDB 609
+            # ("Gas fire or wall heater, balanced flue", flue RS, eff 58%),
+            # the only balanced-flue code in the 601-613 gas block.
+            ("Fire or wall heater with balanced flue", 609),
             # Solid fuel (PCDB 631, eff 0.32 col B).
             ("Open fire in grate", 631),
             ("No Secondary Heating", None),  # no secondary heater lodged