Which device is used to control the action of valves in a heating system?

An actuator is the correct device used to control the action of valves in a heating system. In this context, an actuator is responsible for converting a control signal into mechanical motion to operate the valve. This action can either open or close the valve, allowing for precise control over the flow of heating medium—be it water or steam—through the system. The ability of the actuator to respond to control signals enables the heating system to efficiently regulate temperature and maintain desired comfort levels.

In contrast, a switch is primarily used to turn devices on or off, without directly controlling flow rates or valve positions. A pump helps circulate the heating medium but does not control valves. A thermometer measures temperature but does not influence valve action directly. Thus, the role of the actuator is vital for the responsive management of the heating system’s operation through valve manipulation.