diff --git a/tests/domain/modelling/fixtures/boiler_combi_oil_001431_after.pdf b/tests/domain/modelling/fixtures/boiler_combi_oil_001431_after.pdf
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diff --git a/tests/domain/modelling/fixtures/boiler_combi_oil_001431_before.pdf b/tests/domain/modelling/fixtures/boiler_combi_oil_001431_before.pdf
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diff --git a/tests/domain/modelling/fixtures/boiler_cyl_lpg_001431_after.pdf b/tests/domain/modelling/fixtures/boiler_cyl_lpg_001431_after.pdf
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diff --git a/tests/domain/modelling/fixtures/boiler_cyl_lpg_001431_before.pdf b/tests/domain/modelling/fixtures/boiler_cyl_lpg_001431_before.pdf
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diff --git a/tests/domain/modelling/test_elmhurst_cascade_pins.py b/tests/domain/modelling/test_elmhurst_cascade_pins.py
index 9d8ce4ff..a5cec154 100644
--- a/tests/domain/modelling/test_elmhurst_cascade_pins.py
+++ b/tests/domain/modelling/test_elmhurst_cascade_pins.py
@@ -809,6 +809,53 @@ def test_boiler_combi_overlay_reproduces_the_relodged_after() -> None:
     _assert_overlay_reproduces_after(before, after, option.overlay)
 
 
+def test_oil_combi_overlay_reproduces_the_relodged_after() -> None:
+    # Arrange — an OIL combi (fuel 28, SAP code 130, no cylinder) on a mains-gas
+    # street re-lodged as a gas condensing combi (fuel 28->26, code 104, fanned
+    # flue). Validates the non-gas -> gas conversion: the upgrade targets gas
+    # because a mains-gas connection is present (ADR-0024 revised). Controls are
+    # already adequate (2106), so they are unchanged.
+    before: EpcPropertyData = parse_recommendation_summary(
+        "boiler_combi_oil_001431_before.pdf"
+    )
+    after: EpcPropertyData = parse_recommendation_summary(
+        "boiler_combi_oil_001431_after.pdf"
+    )
+    recommendation: Recommendation | None = recommend_heating(before, _AnyProduct())
+    assert recommendation is not None
+    option = next(
+        o for o in recommendation.options if o.measure_type == "gas_boiler_upgrade"
+    )
+
+    # Act / Assert
+    _assert_overlay_reproduces_after(before, after, option.overlay)
+
+
+def test_boiler_with_already_insulated_cylinder_overlay_reproduces_the_relodged_after() -> None:
+    # Arrange — a gas boiler heating an ALREADY-jacketed cylinder (insulation
+    # type 2 / 80 mm) with no thermostat, re-lodged as a new gas condensing
+    # boiler (code 102) with a cylinder thermostat added. Validates the cylinder
+    # path's skip-jacket branch (the 80 mm jacket is not re-applied) while the
+    # thermostat is still added. (Sourced from an LPG re-lodgement; the Summary
+    # mapper reads its fuel as mains gas — fuel 26 — so this exercises the gas
+    # cylinder path, not a true LPG conversion. The LPG fuel-mapping gap is a
+    # separate mapper-front concern.)
+    before: EpcPropertyData = parse_recommendation_summary(
+        "boiler_cyl_lpg_001431_before.pdf"
+    )
+    after: EpcPropertyData = parse_recommendation_summary(
+        "boiler_cyl_lpg_001431_after.pdf"
+    )
+    recommendation: Recommendation | None = recommend_heating(before, _AnyProduct())
+    assert recommendation is not None
+    option = next(
+        o for o in recommendation.options if o.measure_type == "gas_boiler_upgrade"
+    )
+
+    # Act / Assert
+    _assert_overlay_reproduces_after(before, after, option.overlay)
+
+
 # --- Solar PV cascade pins (ADR-0026) -------------------------------------
 #
 # The solar before/after Summaries lodge *synthetic* PV arrays (each 1.00 kWp,