Primary pumps
Ask for The Drive to...Improve your primary pumping in primary/secondary pumping systems, MN60D.
Secondary pumps
Ask for The Drive to...Improve your secondary pumping in primary/secondary pumping systems, MN60E.
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, greater efficiency can be obtained.
The efficiency comes from utilizing 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, an adjustable frequency drive 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 adjustable frequency drive 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
D1
D2
D3
Cooling coil
Heating coil
Filter
Pressure
signal
Supply fan
VAV boxes
Flow
Flow
Pressure
transmitter
Return fan
3
3
T
130BB455.10
Figure 2.11 Variable Air Volume
Product Overview Design Guide
18 Danfoss A/S © Rev. 2014-01-14 All rights reserved. MG18C522
22
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