diff --git a/src/devices/boiler.cpp b/src/devices/boiler.cpp
index 58fda22fc..4461c852f 100644
--- a/src/devices/boiler.cpp
+++ b/src/devices/boiler.cpp
@@ -577,7 +577,7 @@ Boiler::Boiler(uint8_t device_type, int8_t device_id, uint8_t product_id, const
                           FL_(wwSelTempSingle),
                           DeviceValueUOM::DEGREES,
                           MAKE_CF_CB(set_ww_temp_single));
-    register_device_value(DeviceValueTAG::TAG_BOILER_DATA_WW, &wwSolarTemp_, DeviceValueType::USHORT, FL_(wwSolarTemp), DeviceValueUOM::DEGREES);
+    register_device_value(DeviceValueTAG::TAG_BOILER_DATA_WW, &wwSolarTemp_, DeviceValueType::USHORT, DeviceValueNumOp::DV_NUMOP_DIV10, FL_(wwSolarTemp), DeviceValueUOM::DEGREES);
     register_device_value(DeviceValueTAG::TAG_BOILER_DATA_WW, &wwType_, DeviceValueType::ENUM, FL_(enum_flow), FL_(wwType), DeviceValueUOM::NONE);
     register_device_value(DeviceValueTAG::TAG_BOILER_DATA_WW,
                           &wwComfort_,