From 42e9dafd0bad1d6acb4c43b17549859364ffb75e Mon Sep 17 00:00:00 2001
From: Khalim Conn-Kowlessar <kconnkowlessar@gmail.com>
Date: Tue, 30 Jun 2026 18:03:57 +0000
Subject: [PATCH] =?UTF-8?q?Recognise=20gas=20room-heater=20variants=20by?=
 =?UTF-8?q?=20their=20SAP=20codes=20=F0=9F=9F=A9?=
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../epc/property_overlays/main_heating_system_overlay.py  | 8 ++++++++
 domain/epc/property_overrides/main_heating_system_type.py | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/domain/epc/property_overlays/main_heating_system_overlay.py b/domain/epc/property_overlays/main_heating_system_overlay.py
index f9b004cfc..aee3d3b40 100644
--- a/domain/epc/property_overlays/main_heating_system_overlay.py
+++ b/domain/epc/property_overlays/main_heating_system_overlay.py
@@ -170,6 +170,14 @@ _MAIN_HEATING_CODES: dict[str, int] = {
     # Modern standalone oil room heater — SAP Table 4a 623 ("Oil room heater,
     # 2000 or later", no boiler). Natural fuel heating oil (ADR-0041).
     "Oil room heater, 2000 or later": 623,
+    # Gas room heaters — each catalogue variant to its own SAP Table 4a code
+    # (wide efficiency spread, so no single representative). Natural fuel mains
+    # gas; an LPG dwelling is refined by a `main_fuel` override (ADR-0041).
+    "Gas room heater, condensing fire": 611,
+    "Gas room heater, decorative fuel-effect": 612,
+    "Gas room heater, flush live-effect": 605,
+    "Gas room heater, open flue 1980 or later": 603,
+    "Gas room heater, open flue pre-1980": 601,
 }
 
 
diff --git a/domain/epc/property_overrides/main_heating_system_type.py b/domain/epc/property_overrides/main_heating_system_type.py
index c15afd602..eb4658b84 100644
--- a/domain/epc/property_overrides/main_heating_system_type.py
+++ b/domain/epc/property_overrides/main_heating_system_type.py
@@ -29,4 +29,9 @@ class MainHeatingSystemType(Enum):
     AIR_SOURCE_HEAT_PUMP = "Air source heat pump"
     COMMUNITY_BOILERS = "Community heating, boilers"
     OIL_ROOM_HEATER_POST_2000 = "Oil room heater, 2000 or later"
+    GAS_FIRE_CONDENSING = "Gas room heater, condensing fire"
+    GAS_FIRE_DECORATIVE = "Gas room heater, decorative fuel-effect"
+    GAS_FIRE_FLUSH_LIVE_EFFECT = "Gas room heater, flush live-effect"
+    GAS_FIRE_OPEN_FLUE_POST_1980 = "Gas room heater, open flue 1980 or later"
+    GAS_FIRE_OPEN_FLUE_PRE_1980 = "Gas room heater, open flue pre-1980"
     UNKNOWN = "Unknown"