VAV Diffusers: The Solution to Over Heating and Over Cooling

VAV Diffusers The Solution to Over Heating and Over Cooling

Over-cooling in the summer or over-heating in the winter can impact occupant comfort. There are several solutions for this issue. These include rebalancing the system, adding Terminal Units for those spaces, or adding a VAV Diffuser. The use of a VAV Diffuser requires an understanding of the design, how they work, limitations, and system considerations associated with the product.

VAV Diffuser


The VAV diffuser enables the control of airflow into a room with a connected thermostat. The diffuser includes an actuator (thermal or electronic), linkage, plate damper, and diffuser. The ductwork from the air handling unit is connected to the diffuser in the same way it connects to a standard diffuser. The associated thermostat is in the space and is wired to the VAV controller, if electronic or integrated, if thermal. The electronic VAV diffuser controls provide the ability to link several diffusers to be controlled by a single thermostat.



If the room temperature is below the thermostat setting during cooling, an actuator in the diffuser will close an integral damper to reduce the airflow. Ultimately, this will result in less overcooling of the space. The diffuser would work in the opposite direction during heating. If the room temperature is below the thermostat set point, the damper opens to increase heating. These devices are pressure dependent. The airflow control is dependent on the pressure supplied to them. They do not affect the overall control of the system.

When the VAV is added to an existing VAV or constant volume system controlled by a thermostat in another zone there are some limitations.



Adding a VAV Diffuser can be a simple fix when an occupant isn’t comfortable. However, the information above must be considered to ensure comfort is maintained. If you have any questions about VAV Diffusers or HVAC systems in general, please Contact Us.