EC Constant Volume Fans For Efficient Heat Recovery

An increase in new builds brings new legislation and a surge in the demand for heat recovery products as building efficiency is improved. Buildings are becoming more airtight and consequently less fresh air can circulate. Since all buildings need a source of fresh air, most new buildings now include a form of mechanical ventilation with heat recovery (MVHR). Diagram 1 shows how a simple MVHR system facilitates effective ventilation in a domestic unit.

K39-A7 For Heat Recovery
Homes, classrooms, offices, function rooms, whether domestic or commercial, can benefit from MVHR, improving climate control whilst promoting energy efficiency.

“A heat recovery unit is basically composed of a directly driven fan, an exhauster and a heat exchanger, all perfectly assembled and joined inside a thermal and noise insulated structure. The internal extraction air circuit pass by the exchanger without mixing with the circuit of the external driven air.”

A heat recovery unit is similar to a balanced ventilation system, except it uses the heat in the outgoing stale air to warm up the fresh air going into the building. A typical unit uses two fans, one to remove the household air (exhaust air) and the other to bring in the air (intake air).At the centre of the system lies the hear exchange core, this ore transfers heat from the outgoing stream of air to the incoming stream in the same way that a radiator in the car transfers heat from the engines coolant to the outside air to maintain the cars temperature. The core is composed of a series of narrow alternating passages where airstreams flow. As the streams move through, the heat is transferred from the warm side to the cool side without the two sides ever mixing.

Heat recovery can recover up to 85% of heat in the outgoing airstream making them much more effective than natural methods of ventilation such as opening a window to allow fresh air to enter which would allow the warm air to escape. Then the heating system would need to reheat this new make up air. HVR systems are build for both domestic and commercial properties so the fan speed can be set depending on the needs of each particular building. A slow to medium fan speed may be adequate for a domestic property but may need to run faster for busier commercial properties. For businesses, reusing the heat generated during industrial processes is key. The heat energy can be redirected elsewhere resulting in increased energy savings and reduced energy costs.

By choosing the right heat recovery system, customers can maximise heat conservation, redirection and or re-usage. The recovered heat could be suitable for direct as a recirculated, controlled atmosphere for other parts of the manufacturing process. Learn more about the differences between basic and quality MVHR systems here.

 

Maintaining Constant Volume in HVR Units with EC Fans

When installing a MVHR system, each building will be different with geometry and length of duct work varying resulting in very different pressure losses on each installation.

  • The Axair K39-A7 single inlet from the GRE range of forward curved centrifugal EC fans from Ecofit, shown in diagram 3, is designed with built in constant volume software enabling it to regulate its impeller speed to maintain its preset volume against variable pressure.
  • The fans feature a G9 external rotor motor with input power up to 150Watts
  • With constant volume software on board, the Axair fan can be preset during assembly of the MVHR to deliver the specified volume required on site. The install team then provide power and the MVHR will automatically provide the desired airflow.

About the GRE G9 Fan:

  • Forward impeller galvanised steel,
  • Impeller diameter of 120 up to 180mm,
  • EC external rotor motor 230V50/60Hz and 120V50/60Hz,
  • Integrated electronic
  • Black painted steel steel
  • Maximum airflow of 170 up to 1000m3/h, maximum pressure of 300 up to 800Pa,
  • CE, UL mark,
  • Options: impeller dimension, alarm signal.

K39-A7 Curve Heat Recovery

The same constant volume software is available in a double inlet centrifugal, enabling higher air volumes and system performance, resulting in a cost effective and energy saving device.

How Can Axair Help?

We have a wealth of technical expertise and can assist with fan selection for a wide array of applications in the industrial and OEM market. Download our OEM brochure here.  

Contact us or visit our website for more information on how Axair can assist with Heat Recovery application, increase energy efficiency or any other project on 01782 349430

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