Functions:Heating and Cooling
Packaged rooftop units provide air conditioning through direct contact between condenser coils and outdoor air, eliminating hydronic piping from the air-conditioning system. Many RTU models can also be equipped with a gas boiler to use the same air duct system for heating.
RTUs can be configured as either constant volume (CV) or variable air volume (VAV) systems. However, the VAV configuration provides superior energy efficiency while minimizing air drafts and noise. According to a study carried out by the US Environmental Protection Agency, VAV installations provide energy savings ranging from 10 to 21 percent.
When using a VAV system, it is important to ensure that a minimum outdoor airflow is maintained, even when the total airflow is diminished in response to a reduced cooling load. This feature is sometimes overlooked, which has a negative effect on indoor air quality.