diff --git a/domain/sap10_calculator/tables/pcdb/parser.py b/domain/sap10_calculator/tables/pcdb/parser.py
index 06041443..8e017693 100644
--- a/domain/sap10_calculator/tables/pcdb/parser.py
+++ b/domain/sap10_calculator/tables/pcdb/parser.py
@@ -182,6 +182,13 @@ class HeatPumpRecord:
     `max_output_kw` (spec §A.23 field 30) is the PSR-denominator per
     PDF p.100 line 5946 ("maximum nominal output of the package").
 
+    `heating_duration_code` (format-465 position 48) encodes the
+    package's daily heating duration per SAP 10.2 Appendix N3.5 (PDF
+    p.105 line 6099): "24", "16", "9", or "V" (Variable). Drives the
+    extended-heating-schedule day allocation via Table N4/N5. Per
+    footnote 48, modern records always lodge "V"; the fixed durations
+    are retained for legacy purposes.
+
     `psr_groups` carries the PSR-dependent efficiency table (up to 14
     rows) used by SAP 10.2 Appendix N3.6 (space heating) and N3.7(a)
     (water heating), interpolated at the dwelling's PSR per spec PDF
@@ -199,6 +206,7 @@ class HeatPumpRecord:
     vessel_heat_loss_kwh_per_day: Optional[float]
     vessel_heat_exchanger_area_m2: Optional[float]
     max_output_kw: Optional[float]
+    heating_duration_code: Optional[str]
     psr_groups: tuple[PsrEfficiencyGroup, ...]
     raw: tuple[str, ...]
 
@@ -216,6 +224,10 @@ _HP_IDX_VESSEL_VOLUME_L: Final[int] = 24
 _HP_IDX_VESSEL_HEAT_LOSS_KWH_PER_DAY: Final[int] = 25
 _HP_IDX_VESSEL_HEAT_EXCHANGER_AREA_M2: Final[int] = 26
 _HP_IDX_MAX_OUTPUT_KW: Final[int] = 47
+# Format 465 position 48 — daily heating duration code per SAP 10.2
+# Appendix N3.5 (PDF p.105 line 6099). Cohort ground-truth: "V" lodged
+# on Mitsubishi PUZ-WM50VHA (104568) and Daikin EDLQ05CAV3 (102421).
+_HP_IDX_HEATING_DURATION_CODE: Final[int] = 48
 
 # Format 465 PSR-group block: idx[58] is the group count; groups start
 # at idx[59], 9 fields wide, with PSR / η_space,1 / η_water,3 at the
@@ -315,6 +327,7 @@ def parse_heat_pump_row_raw(raw: tuple[str, ...]) -> HeatPumpRecord:
     def at(idx: int) -> str:
         return raw[idx] if idx < len(raw) else ""
 
+    duration_raw = at(_HP_IDX_HEATING_DURATION_CODE).strip()
     return HeatPumpRecord(
         pcdb_id=int(raw[0]),
         brand_name=at(_HP_IDX_BRAND_NAME),
@@ -331,6 +344,7 @@ def parse_heat_pump_row_raw(raw: tuple[str, ...]) -> HeatPumpRecord:
             at(_HP_IDX_VESSEL_HEAT_EXCHANGER_AREA_M2)
         ),
         max_output_kw=_parse_optional_float(at(_HP_IDX_MAX_OUTPUT_KW)),
+        heating_duration_code=duration_raw if duration_raw else None,
         psr_groups=_parse_psr_groups(raw),
         raw=raw,
     )
diff --git a/domain/sap10_calculator/tests/test_pcdb_table_362_lookup.py b/domain/sap10_calculator/tests/test_pcdb_table_362_lookup.py
index c9bbfda0..f3f8ffeb 100644
--- a/domain/sap10_calculator/tests/test_pcdb_table_362_lookup.py
+++ b/domain/sap10_calculator/tests/test_pcdb_table_362_lookup.py
@@ -57,6 +57,24 @@ def test_heat_pump_record_returns_verified_mitsubishi_ecodan_104568_header() ->
     assert record.max_output_kw == 4.39
 
 
+def test_heat_pump_record_heating_duration_code_for_104568_is_variable() -> None:
+    """SAP 10.2 Appendix N3.5 (PDF p.106) — extended heating duration is
+    sourced from PCDB Table 362 field "Daily heating duration", encoded
+    as "24" / "16" / "9" / "V" (Variable). Per spec PDF p.105 line 6099
+    + footnote 48, modern PCDB records always lodge "V"; the fixed
+    durations are retained for legacy purposes.
+
+    Mitsubishi PUZ-WM50VHA (104568) lodges duration "V" at format-465
+    position 48 — confirmed by inspecting the raw row in pcdb10.dat.
+    """
+    # Arrange / Act
+    record = heat_pump_record(104568)
+
+    # Assert
+    assert record is not None
+    assert record.heating_duration_code == "V"
+
+
 def test_heat_pump_record_returns_none_for_unknown_pcdb_id() -> None:
     """An index number not in Table 362 returns None so callers can fall
     back to a Table 4a heat-pump category default."""