DDC Controlled Chilled Water Actuator

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DDC Controlled Chilled Water Actuator

DDC Controlled Chilled Water Actuator | HVAC Automation. This chilled water actuator is attached to a valve which supplies chilled water to the air handling unit. The air handling has a 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. Demand from the VAV boxes or the HVAC zones. Most DDC controlled actuators work off of a DC volt or current signal.

DDC Controlled Chilled Water Actuator | HVAC Automation

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 water 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. Finally, other voltage ranges for modulating an actuator are 2 to 10 volts DC and 0 to 5 volts DC.

DDC Controlled Chilled Water Actuator | HVAC Automation

Lastly, these systems which automate the HVAC control process are generally referred to as DDC or Direct Digital Controls. Additionally, they may also be referred to as Building Automation Systems or BAS, Building Monitoring Systems or BMS. These are the names that generally go along with these control systems. It is basically hooking up a computer to the HVAC system. Then you program the computer to precisely control the HVAC system.