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This document defines the properties of Micropelt’s battery free, intelligent thermostatic radiator valve (iTRV). MVA009 is an 868MHz EnOcean wireless actuator, which is self-powered through thermal energy harvesting. It is used to single room control heating radiators with standard valve connection M30x1.5. To operate the device, the unit must be paired with a compatible room controller or gateway unit supporting EEP A5-20-06. The pairing is done either via manual 4BS Teach-In or trough EnOcean Remote Commissioning. Once mounted and activated on the valve body, a calibration cycle starts to automatically adapt itself to the individual valve and is ready for use. Adapter are available for a majority of non M30x1.5 valve bodies Ventiladapter / Valve body adapter .

Room controller time schedules can be conveniently used to set individual room temperatures at different times and to a desired °C value. By lowering room temperatures in times of absence, heating costs can be saved without any loss of comfort. Reducing the room temperature by only a few °C does further add to reduction of heating energy consumption and respective CO2 pollution.

The actuator generates the required electrical energy for operation (motor, sensors and radio communication) by means of a built-in thermoelectric generator (TEG) and therefore operates maintenance-free. It is powered from the temperature difference between the radiator heat and ambient temperature (usually room temperature). An additional energy source such as a battery or external power supply is not required. The internal energy storage is fully charged upon delivery, so that sufficient energy is available for installation and up to approximately one year of operation. In winter and heating season, the actuator then supplies itself independently trough the converted heat of the heating circuit. Due to the surplus of generated energy in winter, the internal storage provides sufficient energy for 365 days per year operation including transition periods and summer. 

The product is delivered in mounting position (off) with the valve plunger completely retracted. The drive does recognize when installed on a valve body by means of internal force and travel distance measurement.  Unmounted activation does allow to execute Remote Commissioning operation (Instant SIGNAL telegram is transmitted immediately after each activation from mounting position) but will always return the device back to mounting position to switch off. The drive does have a built-in motor error detection "ACO". The ACO bit does signal incomplete or unsuccessful reference runs from mounting, motor issues during normal operation as well as motor runs from mounting position and back to mounting position. An automatic zero point correction ensures the valve 0% = closed position over time.

The actuator operates with the EnOcean equipment profiles EEP A5-20-06 in either valve position (% value transmitted) or temperature setpoint using its internal temperature control loop (°C setpoint transmitted). The device has a built-in flow temperature sensor to automatically switch its Radio communication cycle (2, 5 or 10 minutes) based on available radiator temperatures. Installation and activation will immediately set the radio communication interval to every 2 minutes and for an installation period of 30 minutes to provide quicker feedback. The ambient temperature value transmitted during such installation period is the raw and actual temperature (Without approximation and smoothing). The device transmits a variety of information to the room control unit including flow and ambient temperature, received radio signal strength, radio communication failure, window open detection. The control unit responds either with a new position value in the range 0% (valve closed) to 100% (valve open) or temperature setpoint (0 ... 40°C). Setpoint changes will be instantly processed and new position values are calculated.

The MVA009 has a red and a green LED to support and indicate successful or failed operations for activation and deactivation.

The device is equipped with a dial for local user setpoint changes that are instantly transmitted to the room controller. The controller however decides whether and how these local changes are accepted and processed by responding with a corresponding telegram answer that includes or ignores the local change request. In valve position mode, all local changes are transmitted as relative values. Changes in temperature setpoint mode are added or subtracted to the current set point temperature and transmitted as absolute temperature value on the controller. Successful local inputs are confirmed by a corresponding number of discreet ton signals. Successive inputs within a maximum time period of 5 seconds time are transmitted as a result value to the room controller. Example: 2 x right (+ 2°C) followed by 2 tone signals. Within the 5 seconds period 3 x left (-3°C) followed by 3 tones. The result of -1°C is transferred after 5 seconds on the room control unit. There will be no further tone signal to confirm the result of -1°C. Incorrect inputs will be displayed by an approx. 2 seconds long red LED signal. Failed attempts will require a waiting period of 2 seconds. Local changes will lead to an instant telegram transmission to the room controller. In case of no response from the correspondent room controller, another telegram will be transmitted 1 second later.

Integrated temperature sensors (valve body and environment) are both used to control the radio interval and internal temperature controller, window-detection as well as freeze protection. The ambient sensor is used to measure the room temperature. During heating operation, the ambient sensor is influenced by the near field of the radiator as well as self-heating of the metallic device housing. The resulting temperature failure due to offset is compensated based on the flow sensor and a built-in temperature compensation (approximation), as well as a subsequent smoothing function. Within the first 30 minutes after activation, the actuator sends the actual ambient temperature without any corrections. After 30 minutes, the device sets the ambient temperature to its smoothing start value to 20°C that will be kept as long as the calibration cycle takes. The approximation process in a non-heating cycle takes 3 x 10 minutes. Device activation in an active heating cycle will extend the start value and smoothing cycle to as long as the measured ambient and flow sensor values stabilize with deviations smaller than 1°C. When operated in temperature setpoint, the use of an external room temperature sensor is recommended which is then transmitted to the MVA009 with every 4BS telegram through the room controller. Without external room sensor, the built-in ambient sensor is used with the respective in accuracy given the nearfield radiator environment or any other related effects such as mounting position, curtains, furniture.

Anti-freeze protection uses the flow sensor integrated in the metallic valve connection. Standard freeze protection is active at <6°C. With a temperature setpoint transmission of 0°C, then the freeze protection temperature is also lowered to 0°C. It does not matter if the 0°C setpoint value was requested by radio or by manual adjustment.

Alternate flashing of red and green LEDs in 0.5 second intervals signals a sensor error (short circuit or interruption). In this condition, normal operation is not possible.

Window open detects any temperature drop within a time period of 2 minutes on the local ambient temperature sensor. Once a given negative temperature change is detected, the device sets the DWO bit and immediately reports the state transmitting a 4BS telegram to the room controller. Its transmitted ambient temperature is the actual temperature value (no approximation or smoothing). The window open detection function is limited to the transmission of data telegrams and setting the DWO bit, no further internal reactions by the actuator apply. The detection of a temperature drop depends on a recognizable stream of cold air in the close environment of the actuator. For a reliable detection, the drive must be installed in unspoilt situation and on radiators below the respective window. Fully opened windows in winter season are usually reliably detected at low outside ambient temperatures. Window in tilt position and heaters in faraway distance to the window cannot be detected reliable. The window open function is independent of the selected communication interval and automatically runs every 2 minutes. Should the temperature fall further and below freeze protection temperature of 6°C (respectively 0°C), the drive automatically opens to prevent from freeze related damages.

Radio failures after 6 unsuccessful 4BS communication attempts in paired situation are reported with its status bit RCE. The actuator automatically switches to its internal temperature control using the last received and valid temperature setpoint from the control unit. With the lack of a valid temperature setpoint °C value (e.g. SPS=0 operation), the internal default value of 21°C is used. Radio signal strength of the received telegram (RSS) is also activated due to lack of incoming data telegrams. The radio communication interval is set to 1x per hour in order to reduce energy consumption during radio failure phases. The local offset function of the dial remains active and any local adjustments are calculated from a default value 21°C. E.g. 5 x left decreases the setpoint from 21°C to 16°C, independent from the last received setpoint value. Due to lack of response from the master control unit keeps the drive this setpoint and regulates accordingly. Consecutive local changes are again calculated from the default value of 21°C, e.g. 3 x right = 24°C followed by 1x right = 22°C. The drive returns to normal operation, once the radio communication is re-established.

When used operating in permanently unheated rooms, the internal storage cannot recharge. If the voltage at the storage falls below a threshold value, the drive moves to the 50% position in order to gain energy again through the heating of the valve (in heating mode)will be discharged. The unit then moves to 50% open position trying to recharge its storage. Operation in little or unheated rooms must be avoided since normal operation can not be guaranteed and a manual battery recharging is needed. If the operation in unheated rooms cannot be avoided, then the use of the standby mode is recommended. The radio communication is stopped, and the storage consequently only discharges very slowly. To reactivate the unit from standby, it is sufficient activate it with the local control only once. As an alternative to standby, there is the option of increasing the radio interval from typically 10 to 60 minutes. The unit remains accessible via radio. By setting the summer bit SB, the radio interval can even be extended to 8 hours, in wich time interval the unit can also be addressed trough radio.

The MVA009 is equipped with hard - and software functions to simplify installation, control and real-time monitoring. Apart from standard, manual 4BS teach-in are EnOcean Remote Commissioning (ReCom) operations available to teach and configure the device prior deployment or during operation. ReCom is operated with separate from 4BS and periodically transmitted SIGNAL (0x09) telegrams. Single or multiple ReCom commands must be executed within an 8 seconds time period after the UNLOCK command. ReCom can be used to set its link-table and change device-internal parameters such as control loop gain, temperature offset parameter or readout of its internal storage value.

The device can be restarted using manual RESET as follows: Turn the dial to the right end stop and hold it for 10 seconds. After the second LED signal than turn briefly against the left stop and release. The drive is restarted and carries out a reference run and activates the 30-minute maintenance interval. The drive then communicates for the next 30 minutes in a 2-minute interval. The ambient temperature is the effective measured temperature of the ambient sensor. After the maintenance interval, the temperature approximation and smoothing function restarts. Existing teach-in connections to the room controller and remote commissioning settings are retained during manual RESET.