From fedae2ea003c686163b5fc839047a1d6b3f96e2d Mon Sep 17 00:00:00 2001
From: Khalim Conn-Kowlessar <kconnkowlessar@gmail.com>
Date: Wed, 1 Jul 2026 16:09:56 +0000
Subject: [PATCH] =?UTF-8?q?Resolve=20an=20electric-CPSU=20override=20to=20?=
 =?UTF-8?q?SAP=20192=20electric=20on=20an=20off-peak=20meter=20?=
 =?UTF-8?q?=F0=9F=9F=A9?=
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../main_heating_system_overlay.py                  | 13 ++++++++-----
 .../property_overrides/main_heating_system_type.py  |  1 +
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/domain/epc/property_overlays/main_heating_system_overlay.py b/domain/epc/property_overlays/main_heating_system_overlay.py
index e15aeeb3c..5d7c3b836 100644
--- a/domain/epc/property_overlays/main_heating_system_overlay.py
+++ b/domain/epc/property_overlays/main_heating_system_overlay.py
@@ -112,10 +112,10 @@ _CATEGORY_10_ROOM_HEATER_CODES = (
 _ELECTRICITY_FUEL = 29
 _HOUSE_COAL_FUEL = 33
 _ELECTRIC_ROOM_HEATER_CODES = frozenset(range(691, 702))
-# Direct-acting electric boiler (SAP Table 4a 191) — unambiguously electric, so it
-# drags electricity like the electric room heaters (ADR-0045, closing the prior
-# no-fuel gap on 191).
-_ELECTRIC_BOILER_CODE = 191
+# Electric boilers — SAP Table 4a 191 (direct-acting) and 192 (electric CPSU) —
+# unambiguously electric, so they drag electricity like the electric room heaters
+# (ADR-0045, closing the prior no-fuel gap on 191/192).
+_ELECTRIC_BOILER_CODES = frozenset({191, 192})
 
 # Heat pumps (SAP Table 4a 211-224 wet, 521-527 warm-air) are category 4 and
 # unambiguously electric (natural fuel 29). Modellable on the default code's SPF
@@ -181,6 +181,9 @@ _MAIN_HEATING_CODES: dict[str, int] = {
     # (direct-acting electric boiler). Unambiguously electric, so it drags
     # electricity below (ADR-0045).
     "Electric boiler": 191,
+    # Electric CPSU — SAP Table 4a 192. Electric (drags 29), on an off-peak Dual
+    # meter (already in _ASSUMED_DUAL_METER_CODES; §12 Rule 1 10-hour) — ADR-0045.
+    "Electric CPSU": 192,
     "Electric room heaters": 691,
     "Solid fuel room heater, closed": 633,
     # Solid-fuel room heaters off the Gas CPSU dumping ground (ADR-0045). SAP
@@ -260,7 +263,7 @@ def _natural_fuel_for(code: int) -> Optional[int]:
         code in _ELECTRIC_ROOM_HEATER_CODES
         or code in _HEAT_PUMP_CODES
         or code == _HHR_STORAGE_CODE
-        or code == _ELECTRIC_BOILER_CODE
+        or code in _ELECTRIC_BOILER_CODES
     ):
         return _ELECTRICITY_FUEL
     if code in _SOLID_FUEL_ROOM_HEATER_CODES:
diff --git a/domain/epc/property_overrides/main_heating_system_type.py b/domain/epc/property_overrides/main_heating_system_type.py
index aaa917df1..866767f4f 100644
--- a/domain/epc/property_overrides/main_heating_system_type.py
+++ b/domain/epc/property_overrides/main_heating_system_type.py
@@ -28,6 +28,7 @@ class MainHeatingSystemType(Enum):
     )
     DIRECT_ELECTRIC = "Direct-acting electric"
     ELECTRIC_BOILER = "Electric boiler"
+    ELECTRIC_CPSU = "Electric CPSU"
     ELECTRIC_ROOM_HEATERS = "Electric room heaters"
     SOLID_FUEL_ROOM_HEATER_CLOSED = "Solid fuel room heater, closed"
     SOLID_FUEL_ROOM_HEATER_OPEN_FIRE = "Solid fuel room heater, open fire"