diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index b4dbd9634..93f76fdb3 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -6691,6 +6691,10 @@ _PASHUB_SECONDARY_HEATING_TYPE_TO_SAP10: Dict[str, int] = {
     # Gas room heaters (Table 4a column A).
     "Flush fitting live fuel effect open front fire, sealed to fireplace": 605,
     "1980 or later - Open front fire with open flue, sealed to fireplace": 603,
+    # Pre-1980 open-fronted gas fire, open flue, not sealed to the fireplace
+    # (no qualifier in the label) — PCDB 601, eff 50%. 602 (601 + back boiler)
+    # rejected: no back-boiler qualifier surveyed.
+    "Pre 1980 - Open front fire with open flue": 601,
     # Solid fuel (eff 0.32 column B).
     "Open fire in grate": 631,
 }