diff --git a/model_data/epc_attributes/MainheatControlAttributes.py b/model_data/epc_attributes/MainheatControlAttributes.py
index a9f9e117..fa9ad52a 100644
--- a/model_data/epc_attributes/MainheatControlAttributes.py
+++ b/model_data/epc_attributes/MainheatControlAttributes.py
@@ -79,6 +79,8 @@ class MainheatControlAttributes(Definitions):
         "rheoligçör t+ól +ó llaw": "manual charge control",
         "rheolaeth amser a rheolaeth parthau tymheredd": "time and temperature zone control",
         "rhaglennydd a thermostatau ar y cyfarpar": "programmer, room thermostat",
+        "rheolyddion i wresogyddion storio sygçön cadw llawer o wres": "controls for high heat retention storage "
+                                                                       "heaters",
     }
 
     def __init__(self, description: str):
diff --git a/model_data/tests/test_data/test_mainheat_control_attributes_cases.py b/model_data/tests/test_data/test_mainheat_control_attributes_cases.py
index d514e43a..8dadd0fb 100644
--- a/model_data/tests/test_data/test_mainheat_control_attributes_cases.py
+++ b/model_data/tests/test_data/test_mainheat_control_attributes_cases.py
@@ -153,4 +153,12 @@ mainheat_control_cases = [
     {'original_description': 'Rhaglennydd a thermostatau ar y cyfarpar', 'thermostatic_control': 'room thermostat',
      'charging_system': None, 'switch_system': 'programmer', 'no_control': None, 'dhw_control': None,
      'community_heating': None, 'multiple_room_thermostats': False, 'auxiliary_systems': None, 'trvs': None},
+    {'original_description': 'Rheolyddion i wresogyddion storio syGÇÖn cadw llawer o wres',
+     'thermostatic_control': None,
+     'charging_system': 'high heat retention storage heaters', 'switch_system': None, 'no_control': None,
+     'dhw_control': None, 'community_heating': None, 'multiple_room_thermostats': False, 'auxiliary_systems': None,
+     'trvs': None}, {'original_description': 'Flat rate charging, TRVs', 'thermostatic_control': None,
+                     'charging_system': 'flat rate charging', 'switch_system': None, 'no_control': None,
+                     'dhw_control': None, 'community_heating': None, 'multiple_room_thermostats': False,
+                     'auxiliary_systems': None, 'trvs': 'trvs'},
 ]