Aldes Parallel Damper In-Line Zone Terminals (ZRT-PDIL) are designed to introduce flexibility and dynamic control to central supply or exhaust ventilation systems. Used in both large and small systems, the ZRT-PDIL regulates ventilation without the need for individual fans or traditional VAV terminal units.

Each ZRT-PDIL is a two-position, pressure-independent terminal with a control damper to regulate high limit on-demand airflow control and integral passive regulators for automatic air balancing of the continuous and boost airflow setpoints. This unique combination provides flexible control schemes without the need for expensive pneumatic, electronic, or DDC control systems.

The ZRT-PDIL is primarily used for combination low-flow indoor air quality ventilation or make-up air, and on demand high-flow spot ventilation using the same central exhaust or supply fan system. This is achieved by integrating a minimum Constant Airflow Regulator (CAR) in the terminal end panel and in-line with the branch duct. The maximum airflow is controlled by a series of 24 VAC or 120 VAC powered motorized damper(s) and a secondary CAR airflow controller. With the maximum-air motorized control damper completely closed, the continuous CAR allows steady, low-volume airflow control.

When other ZRT-PDIL are activated for on-demand control of high flow, the unpowered ZRT-PDIL will maintain the specified continuous rate through the pressure-independent CAR. Opening the ZRT-PDIL’s control damper adds its calibrated boost airflow rate to the continuous setpoint.