VTS introduces Twin Fan systems to its AHUs, in all models between VS180 - 300. With the application to two smaller drives, it is the optimum solution for reducing electric consumption, normally faced by direct driven fans. This also helps to match the airflow of a unit to the actual conditions of the building, as well as to evenly distribute the flow of air in the space preceding and succeeding the fan box, which finally contributes towards highewr effectiveness of the units.

Modern office buildings, the spacious objects, are usually characterized by the high standard and the proper location of air handling units takes place during the designing phase and is conditioned by the size and kind of windows surface, the shape and orientation of a building, temperature of the surroundings, the number and type of sun visors as well as the arrangement plan of building’s interior.

Apart from the maximum effort put into the adaptation of an offer to the needs of particular construction project, manufacturers of air handling units seek the energy-saving solutions which can bring more benefits to surrounding nature and to the investor. The whole trick is to create something that will bring the utmost efficiency in the most simple way. And this is what we would like to discuss…

To meet the expectations of the future users and designers of ventilation and air conditioning systems in terms of highly-efficient air handling units, VTS has supplemented its offer with the new option – direct driven Plug Fans in VS 180-300 units.

Direct driven Plug Fans require applying frequency converters which enable the efficient performance of the fan system in accordance with the technical parameters specified by the designer of the particular ventilation or air conditioning system. VENTUS 180-300 air handling units can provide up to 43000m³/h airflow, which necessitates using electric drives with the power output even up to 22 kW to propel the fans. Applying frequency converters is not the best solution for our customers when it comes to the price of those devices, that is why we – to answer our clients’ needs - have come up with an alternative – two simultaneously working fan units called “Twins”.

TWINS – Simple, effective and economical solution

A system of two fans providing the desired airflow requires applying two drives, which means that the electrical power needed to press the required amount of air is divided into two smaller drives. Two smaller drives weigh less (which is important when servicing a unit) and, moreover, their rated power is smaller. Consequently, smaller rated power of a unit means smaller electrical energy consumption. VENTUS VS 180-300 air handling units with twin fan systems are designed in such a way that the power of one drive does not exceed 11 kW. As a result, the frequency converters and drives are relatively cheap and easily available on the market.

Applying fans without belt drives

Let us remind You: The presence of belt drives results in the loss of additional power required to overcome their resistance. To reduce this effect by maintaining low SFP factor (Specific Fan Power), which represents the power needed to press a specific air unit (W/m³/h), VTS is applying highly efficient fans and the proper cross-sections of units that enable low velocities (2,6-2,8 m3/h), which is the international trend nowadays.

The relation between a pulley and the rotational speed

The selection of pulleys may be a problem, especially if we want to get the ideally matched rotational speed of fan’s rotor. In practice it means that we must tolerate some divergences in unit’s performance. Another disadvantageous feature of belt drives is the wearing-out of wedge belts or pulleys.

Additional elements?

Designers very often demand that the filter is used next to the fan system (so called secondary filter) to block the worn-out elements tearing off of wedge belt. In such cases the automatics securing the performance of the units also require using additional presostat which can control the pressure of air cumulated in the fan and turn off the air handling if the wedge belt breaks.

When we choose to use air handling units with direct drives we do not have to apply any additional elements.

Adjusting the air flow of the units to the conditions in a building

Another benefit is the ability to adjust the airflow of a unit to the conditions in a building by changing the frequency of current set on the converter. Obviously, it cannot always be done in the free scope. We must remember that every fan has the specified characteristics of performance which must be obeyed.

We enhance the efficiency of heat exchangers

Other advantageous feature of applying two identical and simultaneously operating fans is the even distribution of air flow in the space preceding and behind the fan box. The even distribution of air flow means even workload of heat exchangers which contributes to their higher effectiveness.

Below we can compare the electrical energy consumption by the same air handling unit equipped with two options of fan systems: single fan system and twin fan system.

VS-300 supply air handling unit equipped with a filter, cooler, water heater and a fan system (300Pa disposable pressure).

If we assume that the considered air handling unit operates for 12 hours then the savings resulting from applying twin fan system will equal to the values presented in the table below:

To summarize:

Using direct driven fans in VENTUS 180-300 air handling units allows for:

- matching the airflow of a unit to the actual conditions in a building,

- even distribution of air flow in the space preceding and behind the fan box which consequently contributes to the higher effectiveness of a unit.

The discussed solutions with twin fan systems are the alternative to traditional fan systems solutions, still available in VTS offer.