- The pump is installed as a circulator. The T-const. control mode can be used for this application in order to enable safe, hygienic operation.
Temperature control
The pump in the circulation line changes its speed so that the water returning to the tank is always at the desired specified warm water temperature. The temperature setting range on the Wilo-Stratos MAXO-Z ranges from T = 35 °C … 80 °C. The temperature sensor for this purpose is located in the pump. A separate sensor is not necessary for this control. For this application, Wilo recommends the additional control function for detecting thermal disinfection.
- The pump is installed in a storage charging circuit with integrated heat exchanger. The ΔT-const. control mode can be used for this application in order to achieve system optimisation and at the same time increase in efficiency.
Temperature control
The pump control the differential temperature between feed and return to an adjusted setpoint ΔT = 2 K … 50 K. Independent of the differential pressure, the pump provides the exact volume flow required to maintain the specified setpoint temperature difference.
For this purpose, up to two temperature sensors (PT1000 or active sensor with current+C1- or voltage-controlled signal) must be installed in the feed and return of the storage charging circuit. Depending on the installation situation, the sensor in the pump can be used to measure the temperature in the feed and return, so that only one additional temperature sensor needs to be installed in the other pipe. The pump is connected via one of the two analogue inputs.
The correct configuration of the installed temperature sensors is a prerequisite for correctly setting the control function. T1 is measured in the return of the storage charging circuit, and T2 in the feed.
Control is based on the following formula: T1 = T2 + ΔT. T1 is to be seen here as the reference variable and the temperature that can be influenced, which is dependent on the flow rate of the pump. T2 represents a reference value in the system that cannot be directly influenced by the pump. As the setpoint configuration for ΔT occurs without a sign on the pump, the value is adjusted according to the direction of action.
