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variable air valve (VAV)

In an HVAC system, a control unit consisting of a metal box containing damper-position control equipment, a controller, and a sensor. The box is usually supplied with “primary” air through a duct from the main distribution system; the output delivers air to diffusers located in the space being served.
References in periodicals archive ?
There are two basic air valve designs: closed loop systems that measure airflow and modulate the air valve damper with a control loop to maintain setpoint (similar to a standard VAV box), and inherently pressure independent air valves that adjust for changes in duct system pressure using springs and the shape of the valve (e.
Fluid ports allow the air from the VAV box to enter the room and return the air to an exit, maintaining the mass balance.
COST CATEGORIES First Cost HVAC Energy Cost VAV $1,008,000 $457,278 VRF $1,152,000 $279,447 Net present value, VRF--VAV $144,000 -$177,830 PRESENT VALUE Maintenance Repair/Replace Total VAV $44,634 $5,644 $1,515,556 VRF $48,757 $19,828 $1,500,032 Net present value, VRF--VAV $4,123 $14,183 -$15,524 In this 15-year lifecycle case, the VRF alternative has a lower lifecycle cost with the identified parameters.
In order to extend the lifetime of VAV actuator, this algorithm has "dead zone" for the process value, that is, while the measurement value of room pressure is within the range of the "dead zone", VAV actuator holds its current position to prevent unnecessary repositioning.
Also using VAV dampers and altering the size of ducts had a large impact on the specific fan power (SFP) and it reflected in the results.
The sash on an LV hood locks open to full height for set up procedures then self-closes to 18 inches for normal operation, allowing a VAV system to exhaust air at a reduced rate," says Kurt Rindoks, vice president of engineering and product development, Kewaunee Scientific.
This symmetry arises because the effects of the first and third VAV boxes are the same.
Finally, Mumma found that VAV systems--which attempt to control both sensible and latent loads while supplying the proper amount of ventilation--invariably lead to high relative humidity.
The volume includes a p[bar{a}]da index of both the VAV and the PPU (pp.
VAV systems are the most common HVAC system for commercial buildings, but design practices vary widely around the country and even among design firms in a given area.
For example, when we adjust the supply air flowrate to a zone, we build an air-conditioning system adopting the VAV system.