Variable Air Volume Systems - VAV Siemens Controllers

 
What is the difference between CAV and VAV?

CAV and VAV are modern air volume control systems. What is the difference between them? CAV (Constant air volume) is a constant air flow control system, regardless of the current air flow from the air handling unit (flow stabilization). A ventilation plant with constant air volume is generally used to supply just one room or zone. This approach is suitable in certain cases, but does not offer much energy-efficiency.


On the other hand variable air volume (VAV) control refers to a ventilation system that serves multiple rooms/zones from one or more central plants. This system can be controlled based on the actual room load (temperature, air quality or humidity), as a function of a time schedule or, for example, a minimum flow, maintaining a pressure difference or ensuring a certain number of air changes in the room. The ventilation plant output is variable. This approaches offers a high level of energy-efficiency. In addition, VAV is also used in demanding environments such as cleanrooms or fume cupboards.

This is fine but my system needs communication ...

VAV Siemens controllers guarantee interoperability through the use of standardized and open communication protocols (KNX, Modbus RTU, BACNet MS/TP, BACNet IP). VAV controllers can be used in any system, including those of other manufacturers.

Okay, I have a VAV and communication but why SIEMENS?

The main advantages of VAV Siemens controllers are:

• Easy mounting and low installation costs – Fast and robust mounting with single screw shaft fixation with various form-fit inserts available
• Increased productivity through easy programming – Usage of the handheld operating unit AST 20 with copy&paste function and intuitive menu guidance with backlit display makes programming and servicing a simple task
• Matching individual needs – Logo, cable type and length (PVC or halogen free)and plug system as per customer request
• Easy accessible instructions and datasheets - Wiring diagram and Data Matrix Code (DMC) are printed on the devices and offer direct access to key information.
• Position-independent measured value acquisition and high accuracy - Measured value acquisition is independent of the mounting position. High measuring accuracy even in low pressure ranges (below 4 Pa). Temperature compensated and long-term stable without recalibration.

Nice... but what is the best way to control the whole installation?

A VAV installation properly managed from a superior system is able to guarantee savings resulting from energy consumption by air handling units, up to 50%. In this case, the algorithms for controlling air handling units depending on the demand from the rooms are of key importance. If the indoor air quality is good, an energy-efficient solution is to lower the air handling rate of the air handling unit, not to close the VAV.

Of course, the implementation of this type of ventilation system operation algorithm requires extensive experience and appropriate, proven applications, but the effect we are able to achieve by combining demand signals from rooms with the control of air handling units is worth the effort. Siemens, as a leading manufacturer of building automation systems, has prepared applications that guarantee the highest energy efficiency of the ventilation system in the building.

Great! I am building really modern building. What if…

The next step in cost optimization and operation of room automation systems is to combine the functions of VAV regulators described at the beginning of the article with the function of an advanced room automation controller. Such a hybrid controller, in addition to air quality, is able to control installations such as lighting, blinds, radiator, air conditioner, etc. Thanks to this integrated approach, we are able to achieve the highest level of energy efficiency of the building and ensure an appropriate level of thermal comfort and air quality in combination with guaranteeing adequate lighting and sun protection in occupied rooms.

VAV SIEMENS portfolio

VAV Siemens controllers:

• Measuring range 0…500 Pa
• Running time 150 s

• Conformity: CE, RCM, UL, EAC

VAV compact and modular controllers with 0/2...10V control

VAV compact controllers with bus communication

Compact room automation station and actuator combination

About SIEMENS

Siemens has 170 years of experience in a successful and constantly intensified business. The domain of this activity were and are technologies - constantly developed, improved and modernized. Technologies that in effect serve people, make their lives more comfortable, safer and easier. Thanks to the concentration of its departments in the areas of electrification, automation and digitization, Siemens is setting directions for further development. 

This article was written by a company Siemens
Check technical data for air volume regulators with Siemens controllers

Would you like to know more? Read other articles on VAV & CAV volume regulators:

1. Variable Air Volume VAV Regulator
2. Air Volume Regulators CAV & VAV- overview