There are two main types of centralized air conditioning systems. In Constant Air Volume (CAV) systems the air flow rate into the conditioned spaces is kept constant whereas the air temperature changes in order to achieve the desired indoor conditions. On the other hand, Variable Air Volume (VAV) systems supply air into the conditioned spaces at a constant temperature but at a varying airflow rate, based on the heating or cooling load of each space. VAV systems are considered more complex systems but when implemented correctly offer a more cost-effective solution when compared to CAV systems. The proper functioning of a VAV system depends on the performance of the VAV dampers.

A VAV regulator is the device that regulates the amount of air flowing into a zone, and it’s the most vital part of a VAV system. In its simplest form, a VAV damper is essentially a volume control damper with an electric actuator and an airflow measuring cross. Based on the readings from the room thermostat and the airflow sensor on the damper, the actuator regulates the position of the damper blade, and controls the flow of air passing into the zone. Other versions of a VAV damper may also include integrated sound attenuators and/or an electric or water heater to reheat the air before it’s introduced into the room.

Grada International is a well established, high quality VAV damper manufacture with an overall experience of over 50 years in the manufacture of HVAC equipment. The company offers both circular and rectangular VAV dampers with a wide range of available dimensions and actuators. Their three main VAV product families are the BR, BS and the BB

BR – Round VAV damper

The BR models are round VAV unit with low resistance damper blade, supplied with an electronic actuator and aluminium differential pressure sensor. The housing and the damper are made of galvanized steel sheet. This VAV unit can be applied for regulating constant or variable air volumes based on air quality and/or temperature. The damper blade is equipped with an air tight seal and maintenance free bearings. The housing meets Class C following EN1751, damper blade meets Class 2 following EN1751. Available without (BRS) and with (BRD) insulation, and external sound attenuators.

BS – Rectangular VAV damper

Galvanised rectangular VAV unit with counter rotating blades, supplied with an electronic actuator and aluminium differential pressure sensor. This VAV unit can be applied for regulating constant or variable air volumes based on air quality and/or temperature. The aluminium blades are equipped with an airtight seal and maintenance free bearings. Housing meets Class C following EN 12237, blades meet Class 2 following EN 1751. Available without (BSS) and with (BSD) insulation, and external sound attenuators.

BB – VAV damper with sound attenuation

The terminal boxes BBA/BBT are designed for single duct high velocity constant or variable flow rate applications and can be used both in supply (BBT) and exhaust (BBA).The air flow rate control is pressure independent and achieved by a precision engineered damper which modulates in response to a differential pressure sensor and a motorised electronic velocity control device. Direct communication is possible between the VAV boxes and the central control area. The volume control and the complete shut-off of the VAV box are obtained by the same damper. Taking into account the reduced pressure loss in the damper, the boxes need a minimum of inlet pressure which results in remarkable savings in the total energy requirements.