diff --git a/CHANGELOG.md b/CHANGELOG.md
index dbc38ac26..381396edc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -371,7 +371,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 - Renamed project from EMS-ESP-Boiler to EMS-ESP since it's kinda EMS generic now
-- Support for RC20F and RFM20 (https://github.com/proddy/EMS-ESP/issues/18)
+- Support for RC20RF and RFM20 (https://github.com/proddy/EMS-ESP/issues/18)
 - Moved all EMS device information into a separate file `ems_devices.h` so no longer need to touch `ems.h`
 - Telnet commands can be strings now and output is suspended when typing
 
@@ -392,7 +392,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Scanning known EMS Devices now ignores duplicates (https://github.com/proddy/EMS-ESP/pull/30)
 - ServiceCode stored as a two byte char
-- Support for RC20F and RFM20 (https://github.com/proddy/EMS-ESP/issues/18)
+- Support for RC20RF and RFM20 (https://github.com/proddy/EMS-ESP/issues/18)
 
 ## [1.2.3] 2019-01-03
 
diff --git a/src/ems-esp.cpp b/src/ems-esp.cpp
index c259f1a68..44ffee0de 100644
--- a/src/ems-esp.cpp
+++ b/src/ems-esp.cpp
@@ -592,6 +592,9 @@ void publishValues(bool force) {
 
     if (EMS_Boiler.wWActivated != EMS_VALUE_INT_NOTSET)
         rootBoiler["wWActivated"] = _bool_to_char(s, EMS_Boiler.wWActivated);
+    
+    if (EMS_Boiler.wWActivated != EMS_VALUE_INT_NOTSET)
+        rootBoiler["wWOnetime"] = _bool_to_char(s, EMS_Boiler.wWOneTime);
 
     if (EMS_Boiler.burnGas != EMS_VALUE_INT_NOTSET)
         rootBoiler["burnGas"] = _bool_to_char(s, EMS_Boiler.burnGas);
@@ -1506,8 +1509,9 @@ void MQTTCallback(unsigned int type, const char * topic, const char * message) {
         // this is used for example for comfort, flowtemp
         myESP.mqttSubscribe(TOPIC_BOILER_CMD);
 
-        // these two need to be unqiue topics
+        // these three need to be unqiue topics
         myESP.mqttSubscribe(TOPIC_BOILER_CMD_WWACTIVATED);
+        myESP.mqttSubscribe(TOPIC_BOILER_CMD_WWONETIME);
         myESP.mqttSubscribe(TOPIC_BOILER_CMD_WWTEMP);
 
         // generic incoming MQTT command for EMS-ESP
@@ -1621,6 +1625,16 @@ void MQTTCallback(unsigned int type, const char * topic, const char * message) {
         return;
     }
 
+    // wwOneTime
+    if (strcmp(topic, TOPIC_BOILER_CMD_WWONETIME) == 0) {
+        if (message[0] == '1' || strcmp(message, "on") == 0) {
+            ems_setWarmWaterOnetime(true);
+        } else if (message[0] == '0' || strcmp(message, "off") == 0) {
+            ems_setWarmWaterOnetime(false);
+        }
+        return;
+    }
+
     // boiler wwtemp changes
     if (strcmp(topic, TOPIC_BOILER_CMD_WWTEMP) == 0) {
         uint8_t t = atoi((char *)message);
diff --git a/src/ems.cpp b/src/ems.cpp
index cd3cebf24..8dc5771c3 100644
--- a/src/ems.cpp
+++ b/src/ems.cpp
@@ -137,16 +137,16 @@ const _EMS_Type EMS_Types[] = {
     {EMS_MODEL_RC10, EMS_TYPE_RC10Set, "RC10Set", _process_RC10Set},
     {EMS_MODEL_RC10, EMS_TYPE_RC10StatusMessage, "RC10StatusMessage", _process_RC10StatusMessage},
 
-    // RC20 and RC20F
+    // RC20 and RC20RF
     {EMS_MODEL_RC20, EMS_TYPE_RCOutdoorTempMessage, "RCOutdoorTempMessage", _process_RCOutdoorTempMessage},
     {EMS_MODEL_RC20, EMS_TYPE_RCTime, "RCTime", _process_RCTime},
     {EMS_MODEL_RC20, EMS_TYPE_RC20Set, "RC20Set", _process_RC20Set},
     {EMS_MODEL_RC20, EMS_TYPE_RC20StatusMessage, "RC20StatusMessage", _process_RC20StatusMessage},
 
-    {EMS_MODEL_RC20F, EMS_TYPE_RCOutdoorTempMessage, "RCOutdoorTempMessage", _process_RCOutdoorTempMessage},
-    {EMS_MODEL_RC20F, EMS_TYPE_RCTime, "RCTime", _process_RCTime},
-    {EMS_MODEL_RC20F, EMS_TYPE_RC20Set, "RC20Set", _process_RC20Set},
-    {EMS_MODEL_RC20F, EMS_TYPE_RC20StatusMessage, "RC20StatusMessage", _process_RC20StatusMessage},
+    {EMS_MODEL_RC20RF, EMS_TYPE_RCOutdoorTempMessage, "RCOutdoorTempMessage", _process_RCOutdoorTempMessage},
+    {EMS_MODEL_RC20RF, EMS_TYPE_RCTime, "RCTime", _process_RCTime},
+    {EMS_MODEL_RC20RF, EMS_TYPE_RC20Set, "RC20Set", _process_RC20Set},
+    {EMS_MODEL_RC20RF, EMS_TYPE_RC20StatusMessage, "RC20StatusMessage", _process_RC20StatusMessage},
 
     // RC30
     {EMS_MODEL_RC30, EMS_TYPE_RCOutdoorTempMessage, "RCOutdoorTempMessage", _process_RCOutdoorTempMessage},
@@ -1292,6 +1292,28 @@ void _process_UBAMonitorWWMessage(_EMS_RxTelegram * EMS_RxTelegram) {
     EMS_Boiler.wWCurFlow = _toByte(9);
 }
 
+/**
+ * Activate / De-activate One Time warm water 0x35
+ * true = on, false = off
+ */
+void ems_setWarmWaterOnetime(bool activated) {
+    myDebug_P(PSTR("Setting boiler warm water OneTime loading %s"), activated ? "on" : "off");
+
+    _EMS_TxTelegram EMS_TxTelegram = EMS_TX_TELEGRAM_NEW; // create new Tx
+    EMS_TxTelegram.timestamp       = millis();            // set timestamp
+    EMS_Sys_Status.txRetryCount    = 0;                   // reset retry counter
+
+    EMS_TxTelegram.action        = EMS_TX_TELEGRAM_WRITE;
+    EMS_TxTelegram.dest          = EMS_Boiler.device_id;
+    EMS_TxTelegram.type          = EMS_TYPE_UBAFlags;
+    EMS_TxTelegram.offset        = EMS_OFFSET_UBAParameterWW_wwOneTime;
+    EMS_TxTelegram.length        = EMS_MIN_TELEGRAM_LENGTH;
+    EMS_TxTelegram.type_validate = EMS_ID_NONE;               // don't validate
+    EMS_TxTelegram.dataValue     = (activated ? 0x22 : 0x02); // 0x22 is on, 0x02 is off for RC20RF
+
+    EMS_TxQueue.push(EMS_TxTelegram);
+}
+
 /**
  * UBAMonitorFast - type 0x18 - central heating monitor part 1 (25 bytes long)
  * received every 10 seconds
diff --git a/src/ems.h b/src/ems.h
index 8572655fb..59a9bcb7e 100644
--- a/src/ems.h
+++ b/src/ems.h
@@ -408,6 +408,7 @@ void ems_setThermostatMode(uint8_t mode, uint8_t hc);
 void ems_setWarmWaterTemp(uint8_t temperature);
 void ems_setFlowTemp(uint8_t temperature);
 void ems_setWarmWaterActivated(bool activated);
+void ems_setWarmWaterOnetime(bool activated);
 void ems_setWarmTapWaterActivated(bool activated);
 void ems_setPoll(bool b);
 void ems_setLogging(_EMS_SYS_LOGGING loglevel, bool silent = false);
diff --git a/src/ems_devices.h b/src/ems_devices.h
index 9221ae2f2..7c1fb5fa8 100644
--- a/src/ems_devices.h
+++ b/src/ems_devices.h
@@ -26,6 +26,7 @@
 #define EMS_TYPE_UBAMaintenanceStatusMessage 0x1C // is an automatic monitor broadcast
 #define EMS_TYPE_UBAParameterWW 0x33
 #define EMS_TYPE_UBATotalUptimeMessage 0x14
+#define EMS_TYPE_UBAFlags 0x35
 #define EMS_TYPE_UBAMaintenanceSettingsMessage 0x15
 #define EMS_TYPE_UBAParametersMessage 0x16
 #define EMS_TYPE_UBASetPoints 0x1A
@@ -33,6 +34,7 @@
 
 #define EMS_OFFSET_UBAParameterWW_wwtemp 2                  // WW Temperature
 #define EMS_OFFSET_UBAParameterWW_wwactivated 1             // WW Activated
+#define EMS_OFFSET_UBAParameterWW_wwOneTime 5               // WW OneTime loading
 #define EMS_OFFSET_UBAParameterWW_wwComfort 9               // WW is in comfort or eco mode
 #define EMS_VALUE_UBAParameterWW_wwComfort_Hot 0x00         // the value for hot
 #define EMS_VALUE_UBAParameterWW_wwComfort_Eco 0xD8         // the value for eco
@@ -171,7 +173,7 @@ typedef enum {
     EMS_MODEL_ES73,
     EMS_MODEL_RC10,
     EMS_MODEL_RC20,
-    EMS_MODEL_RC20F,
+    EMS_MODEL_RC20RF,
     EMS_MODEL_RC30,
     EMS_MODEL_RC35,
     EMS_MODEL_EASY,
@@ -283,7 +285,7 @@ const _Thermostat_Device Thermostat_Devices[] = {
     // Buderus/Nefit
     {EMS_MODEL_RC10, 79, 0x17, "RC10/Moduline 100", EMS_THERMOSTAT_WRITE_YES},
     {EMS_MODEL_RC20, 77, 0x17, "RC20/Moduline 300", EMS_THERMOSTAT_WRITE_YES},
-    {EMS_MODEL_RC20F, 93, 0x18, "RC20F", EMS_THERMOSTAT_WRITE_YES},
+    {EMS_MODEL_RC20RF, 93, 0x18, "RC20RF", EMS_THERMOSTAT_WRITE_YES},
     {EMS_MODEL_RC30, 67, 0x10, "RC30", EMS_THERMOSTAT_WRITE_YES},
     {EMS_MODEL_RC30, 78, 0x10, "RC30/Moduline 400", EMS_THERMOSTAT_WRITE_YES},
     {EMS_MODEL_RC35, 86, 0x10, "RC35", EMS_THERMOSTAT_WRITE_YES},
diff --git a/src/my_config.h b/src/my_config.h
index dfcd59578..a36662d9d 100644
--- a/src/my_config.h
+++ b/src/my_config.h
@@ -44,6 +44,7 @@
 
 #define TOPIC_BOILER_CMD "boiler_cmd"                         // for receiving boiler commands via MQTT
 #define TOPIC_BOILER_CMD_WWACTIVATED "boiler_cmd_wwactivated" // change water on/off
+#define TOPIC_BOILER_CMD_WWONETIME "boiler_cmd_wwonetime"     // warm warter one time loading
 #define TOPIC_BOILER_CMD_WWTEMP "boiler_cmd_wwtemp"           // wwtemp changes via MQTT
 #define TOPIC_BOILER_CMD_COMFORT "comfort"                    // ww comfort setting via MQTT
 #define TOPIC_BOILER_CMD_FLOWTEMP "flowtemp"                  // flowtemp value via MQTT