Knowledge Base

What is Heat Recovery Wheel? How does it work? ( Frequently asked Question – IGBC AP / LEED Green Associate Exam Preparation)

It is generally difficult for non-Mechanical Engineers to understand the concept of Heat  Wheel. We have made this concept easy for the readers to understand.

Heat Recovery Wheel is also called as Energy Recovery Wheel/Enthalpy wheel/Thermal Wheel/Rotary Heat Exchanger.

Fig.1 Heat Recovery wheel selection

The above figure shows the specific information pertaining to the selection of Heat Recovery Wheel. The below figures shows the details of heat Recovery Wheel for both AHU & FAHU in cross sectional view.

Fig.2 FAHU with Heat Recovery wheel
Fig.3 AHU with Heat Recovery wheel

To simplify the understanding, the working process is explained in points as follows,

  • In general terms it is a type of energy recovery heat exchanger between two streams of air.
  • Buildings use mechanical ventilation to supply fresh air and extract contaminated air from buildings.
  • The fresh air must be either heated or cooled to acceptable temperature and relative humidity. The heating or cooling of fresh air consumes significant energy and on the other hand already conditioned air is being exhausted out.
  • Heat Recovery wheel rotates between the air streams and transfers energy between fresh air and exhaust air. Hence precool or preheat the fresh air hence reducing the cooling or heating energy.

* For more details about calculation on effectiveness of heat recovery wheel based on ASHRAE 84 refer the following link, where we have developed an interactive tool for the users to understand better by feeding the real-time values.

Link :

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Hameed Jasir K S M