HVAC Chilled Water DDC Control Actuator Previous | Home | Next

DDC Controlled Chilled Water Actuator

This chilled water actuator is attached to a valve which supplies chilled water to the air handling unit chilled water coil. The actuator modulates the valve based on a set point inside the DDC program. If the program has trim and respond capabilities the set point will rise up and down based on demand from the VAV boxes. Most DDC controlled actuators work off of a DC volt or current signal. The common chilled water actuator motor is generally powered by 24 volts AC. The actuator has the ability to modulate by the DC signal. If the chilled actuator is a 0 to 10 volt actuator a zero volt DC signal the actuator would be closed if it is a normally closed valve* (*depending if the actuator is normally closed or normally open). If the chilled water actuator gets a 5 volt signal then the actuator will move the valve to a fifty percent position. Therefore, if the chilled water actuator got a 10 volt DC signal it would open 100 percent if it is a normally closed valve. Other actuators work off of a milliamp signal. 0 to 20 milliamps or 4 to 20 milliamps are the usual milliamps signals that will modulate the valve. Other voltage ranges for mudulating an actuator are 2 to 10 volts DC and 0 to 5 volts DC.

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