Merge pull request #1399 from Hestia-Homes/fix/heating-rec-pcdb-boiler-fallback

Classify PCDB-index gas boilers with no SAP code for heating recs (#1388 A#2)

domain/modelling/generators/heating_recommendation.py

@@ -28,6 +28,7 @@ from domain.modelling.measure_type import MeasureType
 from domain.modelling.product import Product
 from domain.modelling.recommendation import Cost, MeasureOption, Recommendation
 from domain.modelling.simulation import EpcSimulation, HeatingOverlay
+from domain.sap10_calculator.tables.pcdb import gas_oil_boiler_record
 from domain.sap10_calculator.tables.table_4b import (
     table_4b_seasonal_efficiencies_pct,
 )
@@ -192,6 +193,19 @@ _WET_BOILER_SAP_CODE_RANGES: tuple[range, ...] = (
 )
 _ELECTRIC_BOILER_SAP_CODE_RANGE = range(191, 197)
 
+# RdSAP main_heating_category values that denote a wet central-heating boiler:
+# 1 ("central heating with separate HW") and 2 ("boiler and radiators"). Both
+# imply a wet primary loop — the fuel (not the category) says gas/oil/electric.
+# Used only for the fallback classification of a lodgement that carries a
+# category but no `sap_main_heating_code` (mirrors the calculator's
+# `cert_to_inputs._is_wet_boiler_main`).
+_WET_BOILER_CATEGORIES: frozenset[int] = frozenset({1, 2})
+# Electricity main-fuel codes: the SAP Table 12 code (30, Elmhurst/cascade) and
+# the raw gov-API enum (29). An electric-fuelled boiler is the electrification
+# path, not a gas swap, so it is excluded from the gas-boiler upgrade even when
+# the SAP code is absent (the code range can't identify it).
+_ELECTRICITY_FUEL_CODES: frozenset[int] = frozenset({29, 30})
+
 # Cylinder jacket end-state (from the after-cert): an 80 mm jacket
 # (`cylinder_insulation_type=2`). The jacket is added only when the existing
 # cylinder is below this thickness — bringing every cylinder up to 80 mm and
@@ -321,8 +335,7 @@ def _system_tune_up_options(
     absent). Each control option is offered only when it genuinely improves the
     existing controls — never a downgrade or a no-op (ADR-0024)."""
     main: MainHeatingDetail = epc.sap_heating.main_heating_details[0]
-    code: Optional[int] = main.sap_main_heating_code
-    if code is None or not any(code in r for r in _WET_BOILER_SAP_CODE_RANGES):
+    if not _is_wet_boiler(main):
         return []
     control = main.main_heating_control
     control_code: Optional[int] = control if isinstance(control, int) else None
@@ -455,31 +468,70 @@ def _boiler_upgrade_eligible(epc: EpcPropertyData) -> bool:
     instead); a non-gas boiler is a fuel switch, so it is never gated on
     efficiency."""
     main: MainHeatingDetail = epc.sap_heating.main_heating_details[0]
-    code: Optional[int] = main.sap_main_heating_code
-    if code is None:
+    if not _is_wet_boiler(main):
         return False
-    if not any(code in r for r in _WET_BOILER_SAP_CODE_RANGES):
-        return False
-    if code in _ELECTRIC_BOILER_SAP_CODE_RANGE:
+    if _is_electric_boiler(main):
         return False
     if not epc.sap_energy_source.gas_connection_available:
         return False
-    if main.main_fuel_type in _GAS_FUEL_CODES and _already_condensing(code):
+    if main.main_fuel_type in _GAS_FUEL_CODES and _already_condensing(main):
         return False
     return True
 
 
-def _already_condensing(sap_main_heating_code: int) -> bool:
-    """Whether an existing gas boiler already meets the new condensing boiler's
-    winter efficiency (SAP 10.2 Table 4b). Non-Table-4b codes (e.g. solid fuel)
-    have no comparable efficiency and so are never treated as already-condensing."""
-    efficiencies: Optional[tuple[float, float]] = table_4b_seasonal_efficiencies_pct(
-        sap_main_heating_code
-    )
-    if efficiencies is None:
+def _is_wet_boiler(main: MainHeatingDetail) -> bool:
+    """Whether the main system is a wet boiler the tune-up / boiler-upgrade
+    generators can evaluate. Identifies by the Table 4a/4b `sap_main_heating_code`
+    when lodged; when it is absent, falls back to the gov-EPC-API lodgement shape
+    (a PCDB Table 105 gas/oil boiler index, or an RdSAP `main_heating_category`
+    of 1/2 "central heating") — the same fallback the calculator's
+    `cert_to_inputs._is_wet_boiler_main` uses, so the generators evaluate the
+    same population the calculator already models as wet boilers (#1388 A#2).
+    Heat pumps (category 4) are never wet boilers."""
+    if main.main_heating_category == _HEAT_PUMP_CATEGORY:
         return False
-    winter_efficiency_pct: float = efficiencies[0]
-    return winter_efficiency_pct >= _NEW_BOILER_WINTER_EFFICIENCY_PCT
+    code: Optional[int] = main.sap_main_heating_code
+    if code is not None:
+        return any(code in r for r in _WET_BOILER_SAP_CODE_RANGES)
+    index: Optional[int] = main.main_heating_index_number
+    if index is not None and gas_oil_boiler_record(index) is not None:
+        return True
+    return main.main_heating_category in _WET_BOILER_CATEGORIES
+
+
+def _is_electric_boiler(main: MainHeatingDetail) -> bool:
+    """Whether the wet boiler runs on electricity — the electrification path, not
+    a gas swap, so it is excluded from the gas-boiler upgrade. Identified by the
+    Table 4a electric-boiler code range when lodged, else by an electricity main
+    fuel (the code range can't identify an electric boiler lodged with no SAP
+    code)."""
+    code: Optional[int] = main.sap_main_heating_code
+    if code is not None:
+        return code in _ELECTRIC_BOILER_SAP_CODE_RANGE
+    return main.main_fuel_type in _ELECTRICITY_FUEL_CODES
+
+
+def _already_condensing(main: MainHeatingDetail) -> bool:
+    """Whether an existing gas boiler already meets the new condensing boiler's
+    winter efficiency. Uses the SAP 10.2 Table 4b figure for the lodged
+    `sap_main_heating_code`; when no code is lodged (the gov-EPC-API PCDB cohort),
+    reads the boiler's declared winter efficiency from its PCDB Table 105 record
+    instead. A boiler whose efficiency cannot be resolved (no Table 4b entry, no
+    PCDB record) is not treated as already-condensing — the upgrade is offered."""
+    code: Optional[int] = main.sap_main_heating_code
+    if code is not None:
+        efficiencies: Optional[tuple[float, float]] = (
+            table_4b_seasonal_efficiencies_pct(code)
+        )
+        if efficiencies is None:
+            return False
+        return efficiencies[0] >= _NEW_BOILER_WINTER_EFFICIENCY_PCT
+    index: Optional[int] = main.main_heating_index_number
+    if index is not None:
+        record = gas_oil_boiler_record(index)
+        if record is not None and record.winter_efficiency_pct is not None:
+            return record.winter_efficiency_pct >= _NEW_BOILER_WINTER_EFFICIENCY_PCT
+    return False
 
 
 def _boiler_combi_overlay(epc: EpcPropertyData) -> HeatingOverlay:

tests/domain/modelling/test_heating_recommendation.py

@@ -278,6 +278,8 @@ def test_ashp_bundle_carries_the_composite_per_dwelling_cost() -> None:
 def test_listed_building_yields_no_ashp_bundle() -> None:
     # Arrange — a listed building protects the fabric; an external ASHP unit is
     # not auto-offered (ADR-0024). The dwelling is on gas, so HHRSH is also out.
+    # It IS a wet gas combi (PCDB index 10328, no SAP code), so a control tune-up
+    # is legitimately offered — but never ASHP or HHRSH.
     baseline: EpcPropertyData = _gas_boiler_house()
 
     # Act
@@ -285,8 +287,11 @@ def test_listed_building_yields_no_ashp_bundle() -> None:
         baseline, _StubProducts(), PlanningRestrictions(is_listed=True)
     )
 
-    # Assert
-    assert recommendation is None
+    # Assert — no whole-system replacement (ASHP / HHRSH); a tune-up is fine.
+    if recommendation is not None:
+        measure_types = {o.measure_type for o in recommendation.options}
+        assert "air_source_heat_pump" not in measure_types
+        assert "high_heat_retention_storage_heaters" not in measure_types
 
 
 def test_conservation_area_still_yields_an_ashp_bundle() -> None:
@@ -507,6 +512,98 @@ def test_off_gas_boiler_yields_no_gas_boiler_upgrade() -> None:
         }
 
 
+# --- PCDB-lodged gas boiler with no SAP code (#1388 Work item A#2) ----------
+
+
+def _pcdb_lodged_gas_boiler_baseline() -> EpcPropertyData:
+    """A mains-gas wet boiler lodged the way the gov EPC API cohort does — a
+    `main_heating_category` (2, "boiler + radiators") and a PCDB Table 105
+    `main_heating_index_number`, but NO `sap_main_heating_code`. Index 5928 =
+    Ideal Classic, 77.1% winter (a pre-condensing 2001 boiler). Reproduces
+    portfolio-814 pids 742304 / 742306 / 742322 / 742325 / 742336, which model
+    to £0 works and a null SAP heating code because the generators keyed on
+    `sap_main_heating_code` alone and never evaluated these boilers."""
+    epc: EpcPropertyData = _gas_boiler_with_cylinder_baseline()
+    main = epc.sap_heating.main_heating_details[0]
+    main.sap_main_heating_code = None
+    main.main_heating_category = 2
+    main.main_heating_index_number = 5928
+    main.main_fuel_type = 26  # mains gas
+    return epc
+
+
+def test_pcdb_lodged_gas_boiler_without_sap_code_yields_a_boiler_upgrade() -> None:
+    # Arrange — a non-condensing (77.1%) mains-gas boiler lodged with only a PCDB
+    # index + category (no SAP code). The calculator already treats this as a wet
+    # boiler (cert_to_inputs._is_wet_boiler_main); the generator must too, so the
+    # inefficient boiler is offered an upgrade instead of silently getting nothing.
+    baseline: EpcPropertyData = _pcdb_lodged_gas_boiler_baseline()
+
+    # Act
+    recommendation: Recommendation | None = recommend_heating(baseline, _StubProducts())
+
+    # Assert — the boiler upgrade is offered, targeting the code-102 end-state.
+    assert recommendation is not None
+    options = {o.measure_type.value: o for o in recommendation.options}
+    assert "gas_boiler_upgrade" in options
+    overlay = options["gas_boiler_upgrade"].overlay.heating
+    assert overlay is not None
+    assert overlay.sap_main_heating_code == 102
+
+
+def test_pcdb_lodged_condensing_gas_boiler_without_sap_code_yields_no_upgrade() -> None:
+    # Arrange — same lodgement shape but a condensing PCDB index (126 = Broag
+    # Remeha, 91% winter ≥ the new boiler's 84%). A like-for-like gas swap gains
+    # nothing, so no boiler upgrade — the dwelling gets a tune-up instead (the
+    # PCDB efficiency stands in for the absent Table 4b code).
+    baseline: EpcPropertyData = _pcdb_lodged_gas_boiler_baseline()
+    baseline.sap_heating.main_heating_details[0].main_heating_index_number = 126
+
+    # Act
+    recommendation: Recommendation | None = recommend_heating(baseline, _StubProducts())
+
+    # Assert — no boiler upgrade; a control tune-up is still offered (the
+    # fixture's controls are already standard 2106, so the zone tune-up is the
+    # offered variant).
+    assert recommendation is not None
+    measure_types = {o.measure_type for o in recommendation.options}
+    assert "gas_boiler_upgrade" not in measure_types
+    assert "system_tune_up_zoned" in measure_types
+
+
+def test_pcdb_lodged_gas_boiler_without_sap_code_is_tune_up_eligible() -> None:
+    # Arrange — the same non-condensing PCDB boiler must also be recognised as a
+    # wet boiler by the tune-up gate (controls/cylinder), not just the upgrade.
+    baseline: EpcPropertyData = _pcdb_lodged_gas_boiler_baseline()
+
+    # Act
+    recommendation: Recommendation | None = recommend_heating(baseline, _StubProducts())
+
+    # Assert — a tune-up option is offered (zone variant; controls are 2106).
+    assert recommendation is not None
+    assert "system_tune_up_zoned" in {o.measure_type for o in recommendation.options}
+
+
+def test_category_2_electric_boiler_without_sap_code_yields_no_gas_upgrade() -> None:
+    # Arrange — a category-2 boiler with no SAP code and no PCDB index, on
+    # electricity (an electric "boiler and radiators, electric" cohort lodges
+    # category 2). Electrification, not a gas swap, is its path, so no gas boiler
+    # upgrade even on a gas street.
+    baseline: EpcPropertyData = _pcdb_lodged_gas_boiler_baseline()
+    main = baseline.sap_heating.main_heating_details[0]
+    main.main_heating_index_number = None
+    main.main_fuel_type = 30  # electricity
+
+    # Act
+    recommendation: Recommendation | None = recommend_heating(baseline, _StubProducts())
+
+    # Assert
+    if recommendation is not None:
+        assert "gas_boiler_upgrade" not in {
+            o.measure_type for o in recommendation.options
+        }
+
+
 def _gas_combi_baseline() -> EpcPropertyData:
     """A mains-gas combi (Table 4b code 112, no cylinder) with inadequate
     controls (2111 "TRVs and bypass" — no room thermostat)."""