TECHNICAL ANNEX
TECHNICAL TERMS
TECHNICAL TERMS
DEFINITION / EXPLANATION
Range limitation (mechanical):
Below the adjusting knob, there are ‘setting flags’ (red / blue) for mechanically delimiting the min. / max. temperature range. In this manner, an undesired mis-setting of the setpoint can be prevented, for example, in children’s rooms or public buildings. Thermo-bimetal is generally constructed of layers of metal or alloys of more or less the same thickness, which are firmly joined to one another and have different coefficients of thermal elongation. As a result, they bend under temperature changes, so that upon heating, the side with the component that has a lower heat elongation becomes hollow. The heat is transferred by conduction, radiation or convection from the surroundings (indirect heating). Defrosting is the regular de-icing or heating up of the heat exchanger or cooling unit to maintain efficient operation of the system. Intrinsic safety / protection against cold: The devices are intrinsically safe, i.e., upon loss of the sensor me- dium owing to sensor rupture, for example, the burner is switched off. Since minus temperatures generate the same effect through volume reduction of the sensor medium, the devices are adjusted by means of the ‘cold screw’ such that they switch off the burner only at temperatures below −15 °C. They can only be switched on again manually at temperatures above approx. −5 °C by means of the manual reset button. The 2-pipe air conditioners are supplied with heating or cooling water for heat exchange, depending on the requirement, through the same pipe system via 2 pipes (inflow and outflow). The 4-pipe air conditioners are supplied with heating or cooling water for heat exchange, depending on the requirement, through a heating circuit and a cooling circuit (4 pipes). The cooling ceiling belongs to the group of panel heaters. Cooling ceilings are used often in office spaces for passive cooling. In such systems, cold water (usually at 16 °C) flows through a network of pipes and cools the room air. Lower inflow temperatures are not possible because of condensation water formation.
Bimetal:
Defrosting:
Intrinsic safety (JTU, JTL)
Air conditioner, 2-pipe fan convector (fan coil): Air conditioner, 4-pipe fan convector (fan coil):
Cooling ceiling:
Neutral zone:
The control range in which neither heating nor cooling takes place is called the neutral zone.
NC contact (bimetal):
The control contact opens with increasing temperature and closes at dropping temperature (for ‘heating’).
Proportional band (p-band):
The proportional band is the range around the target temperature within which the controller delivers a steady output signal. This means that the room temperature is kept more or less constant within the proportional band by the controller (if the heating capacity is sufficient). Control algorithm which, for example, switches off the output when the set temperature is exceeded and switches it on again when the current temperature falls short of the setpoint value. The temperature in the room is always subject to certain variations (control deviations). This deviation results from the switching temperature difference of the controller and the properties of the room, such as heating speed, heat loss etc. In a 3-point control system, the controller can change between the operating modes heating, neutral zone and cooling. Process for generating a continuous-like transmission behaviour in a control path. By varying the power-on time at the input, owing to the time constant of the transmission path, a continuous-like (smooth) signal waveform is generated at its output. Difference between the switching on and switching off of the heater or the controller. a) There is the switching temperature difference of the controller, which depends on the construction of the device. b) There is the switching temperature difference of the room, which is dependent on the behaviour of the entire control path, i.e. on the floor design, the action of external heat sources, the installation location of the controller and the controller itself. The switching temperature difference always refers to the controller. It does not express the actual switch- ing temperature difference of the control path. The latter changes according to the deployment location and conditions. Any indoor temperature is constantly subject to variations. This deviation results from the switching temperature difference of the controller and the properties of the room, such as heating speed, heat loss etc. NO contact (bimetal): The control contact closes with increasing temperature and opens at dropping temperature (for ‘cooling’).
2-point control (ON / OFF control):
3-point control:
PWM (pulse width modulation):
Switching difference (hysteresis):
NO contact (bimetal):
Toggler (bimetal):
This is a toggler with an NC contact and an NO contact. It operates as described for NC and NC contacts.
Split unit / multi-split unit:
Split AC units consist of at least two heat exchangers in which one is installed as a vaporiser in the rooms to be cooled and the other serves as a condenser for heat dissipation. Most split units allow reverse operation for heating the rooms if this is required. Multi-split units consist of several vaporisers connected to a condenser (liquefier). Electrical controllable valve for regulating, for example, the hot water flow in heating systems. A distinction is made here between ON / OFF valve actuators and proportional valve actuators. Proportional valves are designed for connecting controllers with a continuous control mode.
Valve actuator:
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Catalogue 2023
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