In an HVAC plan template, there should be an air return system that sucks in air, draws it through a filter, and then passes it into the main system. The second important part of the HVAC plan template is the filter, and another part of the HVAC system is the exhaust outlets where the exhaust created by the heating system is expelled. As shown, HVAC plans are an important part of a home or a building’s planning as it shows how water networks, boilers, and air ducts are installed in the apartment area to make sure that the proper planning is done in the building.