The energy crisis that has occurred during the last 15 years has pushed the researchers to study new sources of energy. The focus is generally concentrated on renewable energy, however another solution has recently been considered, that is energy recovery. Its main idea is to use the waste energy of any engineering system in another application. Energy recovery concept covers a wide range of domains among them heat recovery. The works existing in the literature concerning HVAC (heating, ventilation, and air-condition) heat recovery are few. However in this paper an investigation on heat recovery in HVAC applications is presented. The three main heat recovery strategies applied to HVAC applications are explained, "immersed condenser heat recovery system", "air to water heat recovery system" and "dual heat recovery system". Advantages and drawbacks are briefly discussed.