Axair Fan Get Specific About Fan Power…

You’ll be aware that Axair offers a wide variety of fans and fan accessories for multi applications into the UK market. One of these being the fan coil industry where the key influencing factor in this ever changing environment is low Specific Fan Power (SFP)

Within a fan coil system, fans are arranged with a heating or cooling coil and ducting arrangement to provide heating, cooling & ventilation, typically within offices and working areas. When new buildings are specified, stringent targets are put into place to ensure all energy consumption is kept to a minimum, ensuring buildings comply with “green targets” and work efficiently. A key factor within the fan coil unit is the fan-motor combination. Energy efficient fans are invaluable in helping to provide the best efficiency so the SFP figure is the measure used for comparison. More often than not utilising a low slippage high-efficiency EC motor and drive combination is the key to achieving the highest efficiency.

Typically fan coil units use between two and five fans to allow each fan to be run at lower speeds which has several benefits:

  • Lower noise – Noise produced varies with the Third power or the change in speed. It does not have a linear relationship. Two fans running at 50% together produce 50dBa in comparison to one fan running at 100% producing 60dBa to achieve the same operating point. This significant 10dBa reduction in noise when running two fans simultaneously is 1/8th the noise of lone fan working at full duty.
  • Efficiency – Two Fans running at 50% consume 48Wa combined energy while one fan running at full speed consumes 100Wa. A significant reduction in power usage when using two fans running simultaneously.

The efficiency of the unit can only be maintained if fans are all running together at their desired operating points. When a fan fails the other fans must then speed up to pick up the duty. With this in mind, we can appreciate the importance of monitoring fan units for fan failures. The Ecofit M41-A5 from Axair has on board failure monitoring, this benefit is an add on for other manufacturers making the unit a cost effective and effective choice when installing this type of application.

The most popular option for fan coil monitoring is a taco output, which generally comes as standard with most manufacturers EC motor ranges. The problem with using taco monitoring is that multi-fan systems within a plenum arrangement are systems of two halves. The inlet side is under a constant low pressure and the discharge side under constant high pressure. As soon as a fan fails and begins to slow down, the taco pulse also slows until the unit stops and runs in reverse. Taco monitored systems will not show fan failure until either the motors are locked, there is a complaint that the unit has lost performance or there is too much noise as one or more fans run full speed to try and pick up the duty lost when most of the fans are failed, causing an inefficient system and high noise levels.

How can Axair help?

Axair Supplier partner Ecofit, has developed a double inlet, centrifugal fan EC fan, the GDS G9 133×190, which not only features a highly efficient EC motor, surpassing ERP 2013 and 2015 but also has a built-in failure monitoring system to detect failures of individual fans or failures of fans within a deck. The failures are monitored via a normally closed contact within the motor which is calibrated to open when the fan speed drops below 200RPM or in the instance that the motor comes to a stop, the monitoring circuit is opened. The management system will detect a fan failure this can then be serviced more effectively.

Contact us for more information on how Axair can assist with Fan Coil application efficiency or any other project on 01782 349430.


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