Ventilation system layout

This mechanical room HVAC plan sample shows the layout of air handler (air handling unit, AHU) equipment: mixing chamber, air filter, fan (blower), heat exchanger coil, diffusers.
"Ventilating (the V in HVAC) is the process of "changing" or replacing air in any space to provide high indoor air quality (i.e. to control temperature, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide). Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air.
Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical/ forced and natural types.
"Mechanical" or "forced" ventilation is used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates much energy is required to remove excess moisture from ventilation air.
Ventilation increases the energy needed for heating or cooling, however heat recovery ventilation can be used to mitigate the energy consumption. This involves heat exchange between incoming and outgoing air. Energy recovery ventilation additionally includes exchange of humidity." [Ventilation (architecture). Wikipedia]
The HVAC floor plan example "Ventilation system layout" was created using the ConceptDraw DIAGRAM diagramming and vector drawing software extended with the HVAC Plans solution from the Building Plans area of ConceptDraw Solution Park.

This HVAC plan sample shows the air handler layout on the floor plan.
"An air handler, or air handling unit (often abbreviated to AHU), is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork.
Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU). An air handler designed for outdoor use, typically on roofs, is known as a packaged unit (PU) or rooftop unit (RTU)." [Air handler. Wikipedia]
The floor plan example "Air handler - HVAC plan" was created using the ConceptDraw DIAGRAM diagramming and vector drawing software extended with the HVAC Plans solution from the Building Plans area of ConceptDraw Solution Park.