diff --git a/CHANGELOG_LATEST.md b/CHANGELOG_LATEST.md
index 3a93bd74c..f4b7ddf98 100644
--- a/CHANGELOG_LATEST.md
+++ b/CHANGELOG_LATEST.md
@@ -4,6 +4,7 @@
 
 ### Added
 
+- Added switchonoptimization for RC310
 - Added enum_controlmode for RC310 (new enum list) 
 - Added nofrostmode, reducemode, reducetemp & noreducetemp for RC310
 - Added emergencyops and emergencytemp, wwmaxtemp, wwflowtempoffset and wwcomfort1 for RC310
diff --git a/src/devices/thermostat.cpp b/src/devices/thermostat.cpp
index 7ce7cdb6b..d4ce46fec 100644
--- a/src/devices/thermostat.cpp
+++ b/src/devices/thermostat.cpp
@@ -1010,6 +1010,7 @@ void Thermostat::process_RC300Curve(std::shared_ptr<const Telegram> telegram) {
 
     has_enumupdate(telegram, hc->controlmode, 0, 1); // 1-weather_compensated, 2-outside_footpoint,3-n/a, 4-room --  RC310  
     has_update(telegram, hc->heatingtype, 1); // 1=radiator, 2=convector, 3=floor
+    has_update(telegram, hc->switchonoptimization, 4);
     has_enumupdate(telegram, hc->nofrostmode, 5, 1); // 1-room, 2-outdoor, 3- room & outdoor
     has_update(telegram, hc->nofrosttemp, 6);
 
@@ -2387,6 +2388,24 @@ bool Thermostat::set_fastheatup(const char * value, const int8_t id) {
     return true;
 }
 
+// Set switchonoptimization RC310
+bool Thermostat::set_switchonoptimization(const char * value, const int8_t id) {
+uint8_t                                     hc_num = (id == -1) ? AUTO_HEATING_CIRCUIT : id;
+    std::shared_ptr<Thermostat::HeatingCircuit> hc     = heating_circuit(hc_num);
+    if (hc == nullptr) {
+        return false;
+    }
+
+    bool b = false;
+    
+    if (!Helpers::value2bool(value, b)) {
+        return false;
+    }
+    write_command(curve_typeids[hc->hc()], 4, b ? 0xFF : 0x00, curve_typeids[hc->hc()]);    
+    return true;
+}
+
+
 // sets the thermostat reducemode for RC35 and RC310
 bool Thermostat::set_reducemode(const char * value, const int8_t id) {
     uint8_t                                     hc_num = (id == -1) ? AUTO_HEATING_CIRCUIT : id;
@@ -3881,6 +3900,7 @@ void Thermostat::register_device_values_hc(std::shared_ptr<Thermostat::HeatingCi
         register_device_value(
             tag, &hc->tempautotemp, DeviceValueType::INT, FL_(div2), FL_(tempautotemp), DeviceValueUOM::DEGREES, MAKE_CF_CB(set_tempautotemp), -1, 30);
         register_device_value(tag, &hc->fastHeatup, DeviceValueType::UINT, nullptr, FL_(fastheatup), DeviceValueUOM::PERCENT, MAKE_CF_CB(set_fastheatup));
+        register_device_value(tag, &hc->switchonoptimization, DeviceValueType::BOOL, nullptr, FL_(switchonoptimization), DeviceValueUOM::NONE, MAKE_CF_CB(set_switchonoptimization));
         register_device_value(tag, &hc->reducemode, DeviceValueType::ENUM, FL_(enum_reducemode1), FL_(reducemode), DeviceValueUOM::NONE, MAKE_CF_CB(set_reducemode));
         register_device_value(tag, &hc->noreducetemp, DeviceValueType::INT, nullptr, FL_(noreducetemp), DeviceValueUOM::DEGREES, MAKE_CF_CB(set_noreducetemp));
         register_device_value(tag, &hc->reducetemp, DeviceValueType::INT, nullptr, FL_(reducetemp), DeviceValueUOM::DEGREES, MAKE_CF_CB(set_reducetemp));
diff --git a/src/devices/thermostat.h b/src/devices/thermostat.h
index 516af32c8..bc1d3483a 100644
--- a/src/devices/thermostat.h
+++ b/src/devices/thermostat.h
@@ -80,6 +80,7 @@ class Thermostat : public EMSdevice {
         char    switchtime1[16];
         char    switchtime2[16];
         uint8_t climate;
+        uint8_t switchonoptimization;
 
         // RC 10
         uint8_t  reducehours;   // night reduce duration
@@ -425,6 +426,7 @@ class Thermostat : public EMSdevice {
     bool set_controlmode(const char * value, const int8_t id);
     bool set_wwprio(const char * value, const int8_t id);
     bool set_fastheatup(const char * value, const int8_t id);
+    bool set_switchonoptimization(const char * value, const int8_t id);
 
     // set functions - these don't use the id/hc, the parameters are ignored
     bool set_wwmode(const char * value, const int8_t id);
diff --git a/src/locale_EN.h b/src/locale_EN.h
index 8ed5594a2..0c1ae03e5 100644
--- a/src/locale_EN.h
+++ b/src/locale_EN.h
@@ -672,6 +672,7 @@ MAKE_PSTR_LIST(nofrostmode1, F("nofrostmode1"), F("nofrost mode")) // RC310
 MAKE_PSTR_LIST(remotetemp, F("remotetemp"), F("room temperature from remote"))
 MAKE_PSTR_LIST(reducehours, F("reducehours"), F("duration for nighttemp"))
 MAKE_PSTR_LIST(reduceminutes, F("reduceminutes"), F("remaining time for nightmode"))
+MAKE_PSTR_LIST(switchonoptimization, F("switchonoptimization"), F("switch-on optimization"))
 
 // heatpump
 MAKE_PSTR_LIST(airHumidity, F("airhumidity"), F("relative air humidity"))