Use the A19CAC changeover control with a wall type, single-pole, double-throw (SPDT) heating and cooling temperature control to automatically select either the heating or cooling mode of a convector or fan coil type system. The maximum ambient temperature is 131°F (55°C).
Figure 1. A19 changeover control
The automatic changeover control eliminates the need for manual selector switches at the temperature control. The control automatically switches to the cooling position when the water temperature decreases to the setpoint, and it switches to the heating position when the water temperature increases to setpoint plus differential. The switch is SPDT, and color-coded for easy wiring.
Important: Use this A19 control only as an operating
control. Where failure or malfunction of the control could lead to personal injury or
property damage to the controlled equipment or other property, additional precautions
must be designed into the control system. Incorporate and maintain other devices, such
as supervisory or alarm systems or safety or limit controls, intended to warn of or
protect against failure or malfunction of the control.