diff --git a/backend/app/db/functions/tests/test_portfolio_functions.py b/backend/app/db/functions/tests/test_portfolio_functions.py
index 957f6663..5e20646c 100644
--- a/backend/app/db/functions/tests/test_portfolio_functions.py
+++ b/backend/app/db/functions/tests/test_portfolio_functions.py
@@ -21,6 +21,7 @@ from backend.app.db.models.recommendations import (
     ScenarioModel,
 )
 from domain.modelling.portfolio_goal import PortfolioGoal
+from tests.utilities.floats import assert_float_matches
 
 
 def _rec(
@@ -83,14 +84,14 @@ def test_aggregation_sums_default_measures_linked_by_plan_id(
     # Assert — the default measures' sums land on the Scenario row
     scenario = db_session.query(ScenarioModel).filter_by(id=7).one()
     assert scenario.cost is not None
-    assert abs(scenario.cost - 1500.0) <= 1e-9  # 1000 + 500
+    assert_float_matches(scenario.cost, 1500.0)  # 1000 + 500
     assert scenario.energy_savings is not None
-    assert abs(scenario.energy_savings - 800.0) <= 1e-9  # Σ kwh_savings
+    assert_float_matches(scenario.energy_savings, 800.0)  # Σ kwh_savings
     assert scenario.energy_cost_savings is not None
-    assert abs(scenario.energy_cost_savings - 200.0) <= 1e-9  # 120 + 80
+    assert_float_matches(scenario.energy_cost_savings, 200.0)  # 120 + 80
     assert scenario.co2_equivalent_savings is not None
-    assert abs(scenario.co2_equivalent_savings - 0.7) <= 1e-9  # 0.5 + 0.2
+    assert_float_matches(scenario.co2_equivalent_savings, 0.7)  # 0.5 + 0.2
     assert scenario.total_work_hours is not None
-    assert abs(scenario.total_work_hours - 8.0) <= 1e-9  # 4 + 4
+    assert_float_matches(scenario.total_work_hours, 8.0)  # 4 + 4
     assert scenario.property_valuation_increase == 2500.0
     assert scenario.labour_days == 3.0
diff --git a/backend/documents_parser/tests/test_heating_systems_corpus.py b/backend/documents_parser/tests/test_heating_systems_corpus.py
index ab7889e4..07e02215 100644
--- a/backend/documents_parser/tests/test_heating_systems_corpus.py
+++ b/backend/documents_parser/tests/test_heating_systems_corpus.py
@@ -59,6 +59,7 @@ from domain.sap10_calculator.rdsap.cert_to_inputs import (
     cert_to_demand_inputs,
     cert_to_inputs,
 )
+from tests.utilities.floats import assert_float_matches
 
 
 _CORPUS_ROOT = (
@@ -984,9 +985,13 @@ def test_oil_6_no_room_thermostat_applies_table_4c2_minus_5pp_space_efficiency()
 
     # Assert — Table 4b 80% winter less the Table 4c(2) -5pp interlock
     # penalty = 75% (matches worksheet (210)).
-    assert abs(inputs.main_heating_efficiency - 0.75) <= 1e-9, (
-        f"oil 6 space efficiency {inputs.main_heating_efficiency:.4f} "
-        f"!= 0.75 (Table 4b 0.80 - Table 4c(2) 0.05 interlock penalty)"
+    assert_float_matches(
+        inputs.main_heating_efficiency,
+        0.75,
+        msg=(
+            f"oil 6 space efficiency {inputs.main_heating_efficiency:.4f} "
+            f"!= 0.75 (Table 4b 0.80 - Table 4c(2) 0.05 interlock penalty)"
+        ),
     )
 
 
@@ -1012,9 +1017,13 @@ def test_oil_6_absent_room_thermostat_applies_table_4f_pump_1_3_multiplier() ->
 
     # Assert — 41 x 1.3 (circulation pump) + 100 (oil flue fan/pump) =
     # 153.3 kWh (matches worksheet (231)).
-    assert abs(inputs.pumps_fans_kwh_per_yr - 153.3) <= 1e-9, (
-        f"oil 6 pumps/fans {inputs.pumps_fans_kwh_per_yr:.4f} kWh "
-        f"!= 153.3 (41 x 1.3 absent-room-thermostat pump + 100 oil aux)"
+    assert_float_matches(
+        inputs.pumps_fans_kwh_per_yr,
+        153.3,
+        msg=(
+            f"oil 6 pumps/fans {inputs.pumps_fans_kwh_per_yr:.4f} kWh "
+            f"!= 153.3 (41 x 1.3 absent-room-thermostat pump + 100 oil aux)"
+        ),
     )
 
 
diff --git a/backend/documents_parser/tests/test_summary_pdf_mapper_chain.py b/backend/documents_parser/tests/test_summary_pdf_mapper_chain.py
index 83d1e094..7a54fdfd 100644
--- a/backend/documents_parser/tests/test_summary_pdf_mapper_chain.py
+++ b/backend/documents_parser/tests/test_summary_pdf_mapper_chain.py
@@ -51,6 +51,7 @@ from domain.sap10_calculator.rdsap.cert_to_inputs import (
     heat_transmission_section_from_cert,
 )
 from domain.sap10_ml.rdsap_uvalues import u_party_wall
+from tests.utilities.floats import assert_float_matches
 from tests.domain.sap10_calculator.worksheet import (
     _elmhurst_worksheet_000474 as _w000474,
     _elmhurst_worksheet_000477 as _w000477,
@@ -1565,8 +1566,8 @@ def test_extension_party_wall_type_read_independently_of_as_main_wall() -> None:
         f"expected Main=4 (CU, U=0.5) + Ext=0 (Unable, U=0.25), got {party_codes}"
     )
     # The two map to different SAP party-wall U-values.
-    assert abs(u_party_wall(4) - 0.5) <= 1e-9
-    assert abs(u_party_wall(0) - 0.25) <= 1e-9
+    assert_float_matches(u_party_wall(4), 0.5)
+    assert_float_matches(u_party_wall(0), 0.25)
 
 
 def test_summary_mapper_raises_on_unmapped_glazing_type_label() -> None:
diff --git a/scripts/eon/find_epc_data.py b/scripts/eon/find_epc_data.py
index df2a9ee3..d963cbf5 100644
--- a/scripts/eon/find_epc_data.py
+++ b/scripts/eon/find_epc_data.py
@@ -17,10 +17,10 @@ from infrastructure.epc_client.epc_client_service import EpcClientService
 # Reduced-Field Synthesis mapper (ADR-0027) re-maps so the SAP10 calculator can
 # re-score them. The commented rows are non-20.0.0 neighbours kept for context.
 UPRNS: list[int] = [
-    # 10003318624,  # 20.0.0  Flat 1, 6 Alexandra Gardens, PO38 1EE
+    10003318624,  # 20.0.0  Flat 1, 6 Alexandra Gardens, PO38 1EE
     # 10003318625,  # 20.0.0  Flat 2, 6 Alexandra Gardens, PO38 1EE
     # 10003318626,  # 20.0.0  Flat 3, 6 Alexandra Gardens, PO38 1EE
-    10003318698,  # 17.1    Flat 4, 6 Alexandra Gardens, PO38 1EE
+    # 10003318698,  # 17.1    Flat 4, 6 Alexandra Gardens, PO38 1EE
     # 100062430247,  # 20.0.0  Flat 5, Adelaide Court, Adelaide Place, PO33 3DG
     # 100062430248,  # 20.0.0  Flat 6, Adelaide Court, Adelaide Place, PO33 3DG
     # 100062430250,  # 20.0.0  Flat 8, Adelaide Court, Adelaide Place, PO33 3DG
diff --git a/tests/utilities/floats.py b/tests/utilities/floats.py
new file mode 100644
index 00000000..77aa44bb
--- /dev/null
+++ b/tests/utilities/floats.py
@@ -0,0 +1,29 @@
+"""Human-readable float assertions for tests.
+
+Replaces the cryptic ``assert abs(actual - expected) <= 1e-9`` idiom with a
+named helper that says what it checks and prints a useful message on failure.
+"""
+
+from __future__ import annotations
+
+from typing import Optional
+
+
+def assert_float_matches(
+    actual: float,
+    expected: float,
+    *,
+    tol: float = 1e-9,
+    msg: Optional[str] = None,
+) -> None:
+    """Assert ``actual`` equals ``expected`` within an absolute tolerance.
+
+    ``tol`` defaults to ``1e-9`` for exact-arithmetic checks; pass a looser
+    value (e.g. ``tol=1e-4``) where the comparison is physically approximate.
+    """
+    diff = abs(actual - expected)
+    detail = f"\n{msg}" if msg else ""
+    assert diff <= tol, (
+        f"expected {expected!r} but got {actual!r} "
+        f"(|diff| {diff:g} > tol {tol:g}){detail}"
+    )