From d8ab3f6ec7dea4b5d738e782ac4020181c23d58b Mon Sep 17 00:00:00 2001
From: Jun-te Kim <juntekim@googlemail.com>
Date: Fri, 19 Jun 2026 14:20:24 +0000
Subject: [PATCH] =?UTF-8?q?Decode=20from-main=20oil/LPG/coal=20and=20gas?=
 =?UTF-8?q?=20boiler-circulator=20water=20heating=20=F0=9F=9F=A9?=
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 domain/epc/property_overlays/water_heating_overlay.py | 6 ++++++
 domain/epc/water_heating_type.py                      | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/domain/epc/property_overlays/water_heating_overlay.py b/domain/epc/property_overlays/water_heating_overlay.py
index e55a578e..3ec952de 100644
--- a/domain/epc/property_overlays/water_heating_overlay.py
+++ b/domain/epc/property_overlays/water_heating_overlay.py
@@ -22,7 +22,13 @@ from domain.modelling.simulation import EpcSimulation, HeatingOverlay
 _WATER_HEATING_CODES: dict[str, tuple[int, int]] = {
     "From main system, mains gas": (901, 26),
     "From main system, electricity": (901, 29),
+    "From main system, oil": (901, 28),
+    "From main system, LPG (bulk)": (901, 27),
+    "From main system, bottled LPG": (901, 3),
+    "From main system, house coal": (901, 33),
     "Electric immersion, electricity": (903, 29),
+    # "boiler/circulator for water heating only" — SAP Table 4a code 911 (gas).
+    "Gas boiler/circulator, mains gas": (911, 26),
 }
 
 
diff --git a/domain/epc/water_heating_type.py b/domain/epc/water_heating_type.py
index 025c669a..e85a195d 100644
--- a/domain/epc/water_heating_type.py
+++ b/domain/epc/water_heating_type.py
@@ -17,5 +17,10 @@ class WaterHeatingType(Enum):
 
     FROM_MAIN_MAINS_GAS = "From main system, mains gas"
     FROM_MAIN_ELECTRICITY = "From main system, electricity"
+    FROM_MAIN_OIL = "From main system, oil"
+    FROM_MAIN_LPG_BULK = "From main system, LPG (bulk)"
+    FROM_MAIN_BOTTLED_LPG = "From main system, bottled LPG"
+    FROM_MAIN_HOUSE_COAL = "From main system, house coal"
     ELECTRIC_IMMERSION = "Electric immersion, electricity"
+    GAS_BOILER_CIRCULATOR_MAINS_GAS = "Gas boiler/circulator, mains gas"
     UNKNOWN = "Unknown"