The Roof Top Unit or RTU as most people call it is the most widely used used HVAC system present in commercial buildings. This type of system packages the heating and cooling into one complete unit. The reason it is called an RTU is because they are mostly found on the roof however, they can be installed on the ground as well.
The cooling system is a standard compressor driven fan-cooled condensing and evaporating system and the heating is most often a gas forced air system.
The most common RTU consists of the following components:
- An evaporator core to absorb heat
- A condenser to release heat
- A compressor to change the refrigerant gas to liquid
- A blower motor and fan to move air
- An intake for makeup or outside air
- A heat source or forced air furnace
- An exhaust flue
The advantages of an RTU is that it typically uses less energy. Since it is assembled and configured in a factory the entire system works as a complete balanced unit. The unit is located on the roof so it does not take away any square footage of the interior of the building. Installation is often easier because only the interior ducts need to be installed separately. Diagnostics and repairs are often easier because all of the components are located in one location.
The disadvantages are; since the unit is located on the roof the maintenance my require a ladder or special hatchway. Another is the replacement may require a crane or other lifting device.
The typical life of a maintained unit could be twenty to twenty-five years.