diff --git a/src/devices/boiler.cpp b/src/devices/boiler.cpp
index acef3e50e..cda032504 100644
--- a/src/devices/boiler.cpp
+++ b/src/devices/boiler.cpp
@@ -941,9 +941,9 @@ Boiler::Boiler(uint8_t device_type, int8_t device_id, uint8_t product_id, const
                               48,
                               63);
         register_device_value(
-            DeviceValueTAG::TAG_DHW1, &wwComfDiffTemp_, DeviceValueType::UINT8, FL_(wwComfDiffTemp), DeviceValueUOM::K, MAKE_CF_CB(set_wwComfDiffTemp), 6, 12);
+            DeviceValueTAG::TAG_DHW1, &wwComfDiffTemp_, DeviceValueType::UINT8, FL_(wwComfDiffTemp), DeviceValueUOM::K, MAKE_CF_CB(set_wwComfDiffTemp), 4, 12);
         register_device_value(
-            DeviceValueTAG::TAG_DHW1, &wwEcoDiffTemp_, DeviceValueType::UINT8, FL_(wwEcoDiffTemp), DeviceValueUOM::K, MAKE_CF_CB(set_wwEcoDiffTemp), 6, 12);
+            DeviceValueTAG::TAG_DHW1, &wwEcoDiffTemp_, DeviceValueType::UINT8, FL_(wwEcoDiffTemp), DeviceValueUOM::K, MAKE_CF_CB(set_wwEcoDiffTemp), 4, 12);
         register_device_value(DeviceValueTAG::TAG_DHW1,
                               &wwEcoPlusDiffTemp_,
                               DeviceValueType::UINT8,