Specifications

ManualsBrandsDanfoss ManualsHome building and DecorVLT HVAC Basic Drive FC 101

2.6.12 Variable Air Volume

VAV, or Variable Air Volume systems, control both the

ventilation and temperature to satisfy the requirements of

a building. Central VAV systems are considered to be the

most energy efficient method to air condition buildings. By

designing central systems instead of distributed systems, a

greater efficiency can be obtained.

The efficiency comes from utilising larger fans and larger

chillers which have much higher efficiencies than small

motors and distributed air-cooled chillers. Savings are also

seen from the decreased maintenance requirements.

2.6.13

The VLT Solution

While dampers and IGVs work to maintain a constant

pressure in the ductwork, a frequency converter solution

saves much more energy and reduces the complexity of

the installation. Instead of creating an artificial pressure

drop or causing a decrease in fan efficiency, the frequency

converter decreases the speed of the fan to provide the

flow and pressure required by the system.

Centrifugal devices such as fans behave according to the

centrifugal laws. This means the fans decrease the pressure

and flow they produce as their speed is reduced. Their

power consumption is thereby significantly reduced.

The PI controller of the VLT

HVAC Basic Drive can be used

to eliminate the need for additional controllers.

Frequency

converter

Frequency

converter

Cooling coil

Heating coil

Filter

Pressure

signal

Supply fan

VAV boxes

Flow

Pressure

transmitter

Return fan

130BB455.10

Illustration 2.11 Variable Air Volume

Product Overview

VLT

HVAC Basic Drive FC 101 Design Guide

18 MG18C502 - Rev. 2013-09-06