diff --git a/backend/documents_parser/tests/test_heating_systems_corpus.py b/backend/documents_parser/tests/test_heating_systems_corpus.py
index e40666b2..36d8ff3c 100644
--- a/backend/documents_parser/tests/test_heating_systems_corpus.py
+++ b/backend/documents_parser/tests/test_heating_systems_corpus.py
@@ -334,8 +334,24 @@ class _CorpusExpectation:
 # Electric 2 SAP -0.1087 → -0.0000 EXACT; joins the lighting-PE
 # deferred cohort (CO2 +11.95 / PE +48.66). Cohort Σ|ΔSAP_c|
 # 0.18 → 0.07 in one slice.
+#
+# Slice S0380.162 closed ashp + gshp by restoring the SAP 10.2
+# Appendix N3.1 (PDF p.105) "default heat gain from Table 5a is
+# included via worksheet (70)" rule for electric heat pumps that DON'T
+# have a PCDB Table 362 record lodged. S0380.160 had over-stripped
+# the gain (zeroed for all HPs); ashp/gshp use Table 4a Cat 4 default
+# cascade and worksheet (70) = 3.0000 W in heating months. Refined
+# `_any_main_system_has_central_heating_pump` HP gate: PCDB-lodged
+# HPs (e.g. cert 0380 cohort with Table 362 record) keep 0 W (pump
+# embedded in COP per N1.2.1); Cat 5 warm-air HPs keep 0 W (no water
+# circulation pump; warm-air fan handled by .161); Cat 4 HPs without
+# PCDB and not warm-air → apply pump gain per N3.1. ashp/gshp ΔSAP
+# -0.024/-0.018 → -0.0000 EXACT; ΔPE +36/+34 → +25.51 (residual
+# narrowed to the Elmhurst-vs-spec HW PE annual-vs-monthly quirk
+# only). Cohort Σ|ΔSAP_c| 0.07 → 0.03 in one slice. All 25 cascade-OK
+# variants now SAP+cost EXACT.
 _EXPECTATIONS: tuple[_CorpusExpectation, ...] = (
-    _CorpusExpectation(variant='ashp', block='11a', expected_sap_resid=-0.0240, expected_cost_resid_gbp=+0.5536, expected_co2_resid_kg=+7.3267, expected_pe_resid_kwh=+36.3435),
+    _CorpusExpectation(variant='ashp', block='11a', expected_sap_resid=+0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=+6.3106, expected_pe_resid_kwh=+25.5090),
     _CorpusExpectation(variant='electric 1', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=-0.0000, expected_co2_resid_kg=+11.9451, expected_pe_resid_kwh=+48.6605),
     _CorpusExpectation(variant='electric 2', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=-0.0000, expected_co2_resid_kg=+11.9451, expected_pe_resid_kwh=+48.6604),
     _CorpusExpectation(variant='electric 3', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=+11.9451, expected_pe_resid_kwh=+48.6604),
@@ -344,7 +360,7 @@ _EXPECTATIONS: tuple[_CorpusExpectation, ...] = (
     _CorpusExpectation(variant='electric 7', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=+11.9452, expected_pe_resid_kwh=+48.6605),
     _CorpusExpectation(variant='electric 8', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=-0.0000, expected_co2_resid_kg=+11.9451, expected_pe_resid_kwh=+48.6604),
     _CorpusExpectation(variant='electric 9', block='11a', expected_sap_resid=+0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=+11.9452, expected_pe_resid_kwh=+48.6605),
-    _CorpusExpectation(variant='gshp', block='11a', expected_sap_resid=-0.0178, expected_cost_resid_gbp=+0.4092, expected_co2_resid_kg=+7.0616, expected_pe_resid_kwh=+33.5171),
+    _CorpusExpectation(variant='gshp', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=-0.0000, expected_co2_resid_kg=+6.3106, expected_pe_resid_kwh=+25.5090),
     _CorpusExpectation(variant='oil 1', block='11a', expected_sap_resid=-0.0000, expected_cost_resid_gbp=-0.0000, expected_co2_resid_kg=+0.0000, expected_pe_resid_kwh=+0.0000),
     _CorpusExpectation(variant='oil pcdb 1', block='11a', expected_sap_resid=+0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=-0.0000, expected_pe_resid_kwh=+0.0000),
     _CorpusExpectation(variant='oil pcdb 2', block='11a', expected_sap_resid=+0.0000, expected_cost_resid_gbp=+0.0000, expected_co2_resid_kg=-0.0000, expected_pe_resid_kwh=+0.0000),
diff --git a/domain/sap10_calculator/worksheet/internal_gains.py b/domain/sap10_calculator/worksheet/internal_gains.py
index c2a6d65a..8e6784e1 100644
--- a/domain/sap10_calculator/worksheet/internal_gains.py
+++ b/domain/sap10_calculator/worksheet/internal_gains.py
@@ -714,13 +714,35 @@ def _any_main_system_has_central_heating_pump(epc: EpcPropertyData) -> bool:
 
     Mirrors `cert_to_inputs._is_wet_boiler_main` — see docstring there
     for the kWh-side parallel in Table 4f.
+
+    Electric heat pump exception per SAP 10.2 Appendix N3.1 (PDF p.105):
+    "For electric heat pumps: The electricity used by the water
+    circulation pump or fan is included within the calculated annual
+    space and hot water heating efficiency and is not included in
+    worksheet (230c). **The default heat gain from Table 5a is included
+    via worksheet (70).**" → Cat 4 HPs WITHOUT a PCDB record (Table 4a
+    default cascade) get the Table 5a default pump gain. Cat 4 HPs
+    WITH a PCDB record (Table 362) embed the pump gain in the COP →
+    no separate Table 5a gain. Cat 5 warm-air HPs (codes 521/523-527)
+    distribute via fans, not a water pump — handled by the warm-air
+    fan row of Table 5a (see `_any_main_system_has_warm_air_distribution`).
     """
     details = epc.sap_heating.main_heating_details
     if not details:
         return False
     for d in details:
         if d.main_heating_category == _HEAT_PUMP_MAIN_HEATING_CATEGORY:
-            continue
+            # PCDB Table 362 record → pump electricity AND gain are
+            # embedded in COP (Appendix N1.2.1); no separate gain row.
+            if d.main_heating_index_number is not None:
+                continue
+            # Cat 5 warm-air HP (codes 521/523-527) → no water pump.
+            code = d.sap_main_heating_code
+            if code is not None and code in _TABLE_4A_WARM_AIR_SAP_CODES:
+                continue
+            # Cat 4 HP, Table 4a default cascade → apply Table 5a
+            # pump gain per Appendix N3.1.
+            return True
         code = d.sap_main_heating_code
         if code is not None and any(
             code in r for r in _WET_BOILER_SAP_CODE_RANGES
diff --git a/domain/sap10_calculator/worksheet/tests/test_internal_gains.py b/domain/sap10_calculator/worksheet/tests/test_internal_gains.py
index bd6695d7..c63eea1d 100644
--- a/domain/sap10_calculator/worksheet/tests/test_internal_gains.py
+++ b/domain/sap10_calculator/worksheet/tests/test_internal_gains.py
@@ -575,6 +575,73 @@ def test_internal_gains_from_cert_reproduces_000490_worksheet_end_to_end() -> No
         assert result.total_internal_gains_monthly_w[m] == pytest.approx(expected_73[m], abs=1e-1), f"(73) month {m+1}"
 
 
+def test_internal_gains_pumps_fans_applies_3w_pump_gain_for_cat4_hp_without_pcdb() -> None:
+    """SAP 10.2 Appendix N3.1 (PDF p.105) — "For electric heat pumps:
+    The electricity used by the water circulation pump or fan is
+    included within the calculated annual space and hot water heating
+    efficiency and is not included in worksheet (230c). The default
+    heat gain from Table 5a is included via worksheet (70)."
+
+    The pump GAIN is included via Table 5a's "Central heating pump in
+    heated space" row even though the pump ELECTRICITY is hidden in
+    the COP. Worksheet evidence (controlled-variable corpus):
+      - ashp (Cat 4 HP, code 214 air-to-water, "Post 2013" pump,
+        no PCDB record): (70) = 3.0000 W heating-mask
+      - gshp (Cat 4 HP, code 211 ground-source, "Post 2013" pump,
+        no PCDB record): (70) = 3.0000 W heating-mask
+
+    PCDB Table 362 HP records embed the pump in the COP including the
+    gain — for those certs (70) = 0 (e.g. cert 0380 cohort). Cat 5
+    warm-air HPs (codes 521/523-527) have no water circulation pump;
+    their fan gain is separately handled via the Table 5a "Warm air
+    heating system fans" row (S0380.161).
+
+    Pre-slice S0380.160 zeroed pump gain for all HPs; this test forces
+    a finer-grained gate: Cat 4 HP + no PCDB record + non-warm-air
+    code → apply the pump gain.
+    """
+    # Arrange — Cat 4 ASHP (code 214) without PCDB index, "Post 2013"
+    # pump age → 3 W per Table 5a.
+    sap_heating = SapHeating(
+        instantaneous_wwhrs=InstantaneousWwhrs(),
+        main_heating_details=[
+            MainHeatingDetail(
+                has_fghrs=False,
+                main_fuel_type=30,
+                heat_emitter_type=1,  # radiators
+                emitter_temperature=1,
+                sap_main_heating_code=214,
+                main_heating_category=4,  # HP
+                main_heating_control=2106,
+                central_heating_pump_age_str="Post 2013",
+            ),
+        ],
+        has_fixed_air_conditioning=False,
+    )
+    epc = make_minimal_sap10_epc(
+        total_floor_area_m2=90.0,
+        low_energy_fixed_lighting_bulbs_count=6,
+        sap_windows=[],
+        sap_heating=sap_heating,
+    )
+
+    # Act
+    result = internal_gains_from_cert(
+        epc=epc,
+        dwelling_volume_m3=227.25,
+        heat_gains_from_water_heating_monthly_kwh=(0.0,) * 12,
+        overshading=OvershadingCategory.AVERAGE,
+    )
+
+    # Assert — 3 W in heating months (Jan-May, Oct-Dec), 0 in summer.
+    expected = (3.0, 3.0, 3.0, 3.0, 3.0, 0.0, 0.0, 0.0, 0.0, 3.0, 3.0, 3.0)
+    for m in range(12):
+        assert abs(result.pumps_fans_monthly_w[m] - expected[m]) <= 1e-9, (
+            f"(70) month {m+1} = {result.pumps_fans_monthly_w[m]:.4f}, "
+            f"expected {expected[m]:.4f}"
+        )
+
+
 def test_internal_gains_pumps_fans_adds_warm_air_fan_gain_for_cat5_hp_main() -> None:
     """SAP 10.2 Table 5a (PDF p.177) row "Warm air heating system fans a) c)"
     — gain = SFP × 0.04 × V (W). Default SFP = 1.5 W/(l/s) per footnote c