This document describes the features and characteristics of the RCU20 room temperature controller released by Siemens Building Technologies in 2003. The controller is equipped with an LCD display and can be used for temperature control in heating or cooling systems. It features PI control, three outputs, and automatic cooling/heating switching. It is designed for temperature control in individual ventilation or air conditioning rooms and can control three-way valve actuators and three-way air valve actuators.
The RCU20 is a room temperature controller with a built‑in sensor and three‑position actuator outputs. It supports PI control, automatic heating/cooling switching, and an energy‑saving mode with adjustable set‑point limits.
The manual covers mounting, wiring (including AC230 V three‑position outputs Y1, Y2, N), safety precautions, environmental limits, and detailed technical data such as power supply, frequency, and proportional bands. Ordering information for accessories and sensor options is also included.
| Power supply voltage | AC230 V ±10/‑15 % |
|---|---|
| Frequency | 50/60 Hz |
| Maximum power consumption | 6 VA |
| Integral time | 5 minutes |
| Set‑point range | 8 °C … 30 °C |
| Output voltage (Y1, Y2) | AC230 V |
| Maximum output current | 2 A |
| Insulation rating | 4 kV |
| Storage temperature range | -20 °C … +70 °C |
The controller operates on AC230 V with a tolerance of ±10/‑15 %.
The automatic switching sensor (QAH11.1+ARG86.3) changes mode based on water temperature: above 28 °C it switches to heating, below 16 °C it switches to cooling.
Outputs Y1 = open, Y2 = close, and N = neutral are provided, each at AC230 V.
Storage conditions comply with IEC721‑3‑1, allowing temperatures from –20 °C to +70 °C and humidity below 95 % RH.