OLD-FASHIONED pumps, fans and compressors in heating, ventilation and air-conditioning systems consume an unnecessarily high amount of energy and with the utilisation of fans only expected to increase further, it is high time to act and use effective measures to curb consumption.
Today, almost all fans built into comfort systems are operated with a controller, the main goal of which is to achieve demand controlled ventilation. These fans mostly run with an AC motor (asynchronous motor) that transforms energy that is not used into heat — quite a normal process, which is identical for each type of control unit.
The standard control systems of those AC fans are normally phase-cutting systems or thyristor units (also called dimmer), which is the most simple version of speed controllers for small fans. For bigger fans either a five-step or multiple-step transformers are used. Such a transformer can easily be integrated into 230 V or 400 V systems. Both types of speed control are widely accepted. Fans driven by a standard IEC (International Electrotechnical Commission)-rated motor are speed controlled by a frequency inverter.
However, that is proving expensive for those who want to cut on energy costs. Keeping that in view, Systemair has introduced electronically commuted (EC) motors. Demand for these motors is increasing because of their economical handling of energy and their excellent controllability.
These motors use an electronic control (commutation unit), making the fan generally operate in the optimum modus. This means that the proportion of effective used energy by EC motors, compared to AC motors, is much higher. At the same time, energy feed-in is very low. Basically, only a 0-10 V signal is needed.
Apart from their energy-efficiency, Systemair fans are also extremely convenient and time-saving to install. There is no need for additional wiring, as connection to a switchboard with separate power and electronic control unit is not required. Besides they can be used virtually worldwide, as they work with standard main supply.

 

Air volume control
Systems intended to provide the same air volume all the time are called constant air volume systems. In such systems, the fans automatically adjust to the set air volume. The intelligent and innovative motor technology in the Systemair domestic heat recovery unit VR 400 EV/EC even goes one step further and is able to include a so-called balanced system. An additional sensor monitors the supply air and exhaust air to be absolutely equal.
Such systems avoid under- or overpressure in a building, which might be a problem especially with ovens having an open fire system. Independent from the pressure situation in the system, that is by clogged filters, the unit always supplies the set air volume. This innovative system solution offers highest comfort in the area of domestic ventilation.

 

Pressure control
The application of a pressure-controlled system offers advantages when the requirements in a ventilation system are constantly changing. One good example is a typical application in a hotel: the varying use of bathrooms, for example, especially during the morning hours, makes high demands on an exhaust system. The ideal solution is the use of a pressure-controlled system.
The installation is easy to handle, as all exhaust air ducts are collected in one common exhaust air shaft, where the complete load on the system being measured. The exhaust air fan, very often a roof fan, is mounted at the end of the system. The built-in pressure control in the Systemair DVC-P roof fan, controls the fan depending on the load, according to the requirements made on the system.
In the bathrooms, electrical exhaust air valves have to be installed. These open, for example, when the light switch is activated, thus causing a pressure drop in the system. As the control is set to keep a constant pressure, it increases the air volume of the fan until the set pressure is reached.
This solution offers a lot of benefits. Beside the energy savings, it stays enjoyably quiet in the bathroom. At the same time, the speed adaption results in a minimum acoustic emission. For consultants, this complete system offers reduced planning efforts. Systemair provides the whole system from one source.

 

Temperature control
In modern supply air systems, room sensors measure the temperature felt by people, in order to achieve optimum compartment air. Temperature sensors measure a certain upper limit or lower limit and adjust the fan accordingly to run on a higher or lower air volume. The temperature sensor adjusts the fan automatically, without the need of additional control units.
Systemair uses the new EC-technology in the roof fans DVC, the square duct fans MUB-EC, the circular duct fans K-EC and the box fans KVKE-EC. The range is completed by the domestic heat recovery units VR and VM as well as compact units Rotovex and Topvex. In short, the advantages of EC motors include:
• Maintained efficiency throughout the motor speed range, no power loss or increased sound level at start-up and low speed means reduced operating cost;
• Low heat losses and thereby lower risk of overheating;
• Easy to control, including by remote control;
• All controlling and protection electronics are integrated into the motor, which eliminates the risk of connection errors;
• Takes less space than the corresponding AC-motor;
• Service life not affected by lowering the speed gives less need for maintenance and
• Low sound level.
* Systemair is a leading ventilation company with operations in 38 countries in Europe, Asia, Middle East, South Africa, North America and Australia. Its products are marketed under the brand names Systemair, Frico, Veab and Fantech.
The Systemair brand represents a standardised range of ventilation products, mainly developed in-house, such as fans, air terminal devices and air handling units.