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Controlling the flow temperature at which the heat pump operates is one of the most important factors affecting the efficiency of the heating system. It is estimated that lowering the temperature by 1 o C increases the efficiency factor of a heat pump by up to 2%.
In Mitsubishi Electric Ecodan heat pumps, the flow temperature can be controlled in three different ways:
Auto-adaptation (room temperature control)
Heating curve
Constant flow temperature
Auto-adaptation:
Setting up a heat pump does not have to be difficult, tedious or complicated. In auto-adaptation mode, the only parameter that interests the user is the temperature setting they wish to maintain inside the building. The entire optimization of the heat pump's economics is taken over by the advanced Ecodan heat pump algorithm. In this mode, it is relevant that the outside temperature influences the flow temperature setting. In the heating curve and constant flow temperature modes, the room thermostats only act as a "limiter" for the heat pump operation. Their reading does not directly affect the operation of the heat pump.
In auto-adaptation mode, the flow temperature of the heating system is primarily influenced by the outside temperature. This is what the heat pump measures first. This value is then corrected based on the difference between the actual (measured) and set room air temperatures. The effect of this is to regulate the compressor frequency so as to avoid fluctuations in the room temperature and to reduce the ON/OFF cycles of the outdoor unit. All this happens with a calculation interval of only 1min. It is therefore an extremely fast-acting and responsive algorithm.
If the room temperature is too low, the first thing a heat pump will do is warm up the building quickly. After all, the user wants to maintain a stable temperature that is suitable for his or her thermal comfort. The flow temperature will be increased, at 1-minute intervals, which will quickly raise the temperature in the building. When the internal temperature starts to approach the level set by the user, the heat pump will start to lower the flow temperature, reducing the amount of energy transferred to the building. The most important is stability. Auto-adaptation will lower the flow temperature to a level that ensures a constant comfortable room temperature. This ensures the lowest possible flow temperature for the heating system and continuous operation of the outdoor unit. This reduces the ON/OFF cycles which, if repeated too often, have a negative effect on the economy of operation and significantly shorten the service life of the heat pump.
If the desired room temperature is reached too quickly, as a result of e.g. an excessively high flow temperature, the heat pump will memorize this situation to prevent it from occurring in future.
The auto-adaptation mode eliminates problems associated with an incorrectly programmed heat pump, e.g. a wrongly set heating curve, the setting of which is a key element of any installation. Many times it turns out that the heating curve set when installing the system is not the correct one. In such a situation, the curve needs to be corrected, e.g. by moving it upwards when the house is too cold, or - accordingly - downwards when it is too warm. This problem, however, is completely eliminated by Mitsubishi Electric's auto-adaptation mode. The heat pump automation decides what the correct, most efficient flow temperatures should be to ensure that the internal temperature set by the user is comfortably reached.
A measurement of the internal temperature is required for correct operation and activation of the auto-adaptation mode in Mitsubishi Electric Ecodan heat pumps. This measurement can be done in three different ways, i.e. using the wireless room thermostat transmitter + receiver or the main heat pump controller moved into the room or the TH1 temperature sensor:
- Wireless room thermostat transmitter PAR-WT50R-E + receiver PAR-WR51R-E
- Ecodan heat pump main controller relocated to room
- TH1 temperature sensor (PAC-SE41TS-E) installed in the room
Heating curve:
This is the relation between the flow temperature and the outside temperature. On the controller it is represented as a graph where the outside temperature is on the X axis and the flow temperature is on the Y axis. In Misubishi Electric heat pumps, the heating curve is defined by setting two points. However, it is possible to correct the slope of the curve by adding a third point. There is a fairly simple relation - as the outside temperature falls, the flow temperature rises.
On the heat pump's main controller, we can increase/decrease the current flow temperature resulting from the relation. However, it is important to note that we are increasing or decreasing the flow temperature (not the room temperature), providing more or less energy to the room.
A system controlled by a heating curve can be fitted with a room thermostat. It acts as a "limiter" on the whole system, blocking its operation but having no influence on the flow temperature value.
Constant flow temperature:
The heat pump maintains a constant flow temperature during operation, set on the main pump controller. As with the heating curve, the system can be equipped with a room thermostat.
