Editing Heat recovery ventilation (section)

== Working principle ==
A heat recovery system is designed to supply conditioned air to the occupied space to maintain a certain temperature.<ref>{{Cite book|title=HVAC fundamentals|last=S. C. Sugarman|publisher=The Fairmont Press, Inc|year=2005}}</ref> A heat recovery system helps keep a house ventilated while recovering heat being emitted from the inside environment. The purpose of heat recovery systems is to transfer the [[thermal energy]] from one fluid to another fluid, from one fluid to a solid, or from a solid surface to a fluid at different temperatures and in thermal contact. There is no direct interaction between fluid and fluid or fluid and solid in most heat recovery systems. In some heat recovery systems, fluid leakage is observed due to pressure differences between fluids, resulting in a mixture of the two fluids.The purpose of an energy recovery system is to reduce the energy required for heating, cooling, or ventilating the space by repurposing the exhaust air's energy.<ref>{{Cite book|title=Fundamentals of Heat Exchanger Design|last=Ramesh K. Shah, Dusan P. Sekulic|publisher=New Jersey: John Wiley & Sons, Inc|year=2003}}</ref>