period two
Chilled-Water System Design
notes
Load-Terminal Control Options
▲Three-way modulating valve
▲Two-way modulating valve
▲Face-and-bypass dampers
Figure 33
Load-Terminal Control
The purpose of load-terminal control is to modulate the flow of air or water through the coil to maintain building space comfort. This is accomplished by measuring the temperature of the supply air or space. The temperature then converted to an electronic signal that modulates the capacity of the cooling coil to match the changing load in the space.
Three methods of load-terminal control are commonly used in chilled-water systems.
nThree-way modulating valve control
nTwo-way modulating valve control
nFace-and-bypass damper control
Each of these methods has a different effect on the operation of the system.