MAH heat recovery unit. As use of air conditioning in communities spreads nowadays, air in air-conditioned places has been widely polluted. As a result, people’s health is directly affected. To improve air quality in closed buildings and save energy, Mammoth Inc. has produced the efficient new-generation make-up air units which fully meet the desire of people for high air quality in working and living environments and, at the same time, have high efficiency of energy recovery. Fresh air and energy saving are two important features of this product. This make-up air unit can be used to effectively recover wasted energy in indoor discharge air during ventilation and maximize energy conservation. Air suction and discharge operations take place at the same time at runtime to build a very comfortable indoor climate. The make-up air unit and the air conditioning system work together to increase freshness and maintain target temperature and humidity of room air, and reduce fresh air load as well as capacity and daily operating costs of the air conditioning equipment so as to reach the double goals of air cleaning and energy saving. Mammoth make-up air units are available in two optional types (ceiling-hung and horizontal). With wide varieties and air volume, the product is suitable for almost all places with fresh air requirement such as offices, meeting halls, exhibition halls, theaters, guest houses, hospitals, dwelling houses, apartments, and factories and mines.