The RTU is the most widely used commercial heating and the cooling unit found in the U.S. The rooftop unit is sometimes called a package unit, as all its components are contained in one unit.
The RTU is usually a direct-expansion (DX) unitary system, which means that the air is cooled by a refrigerant, and can be either fan-cooled or water-cooled. Heat is typically provided in a fuel-fired furnace or supplemental electrical coils housed inside the unit.
A typical RTU consists of:
- an evaporator core, which absorbs heat;
- a condenser, which releases heat;
- a compressor (the motor compresses the refrigerant gas and changes it to a liquid under pressure);
- a blower motor and fan;
- a cooling motor and fan;
- an intake for outside air;
- a heat source (furnace); and
- an exhaust flue.
The RTU connects to the building’s return air and supply ducts.
Advantages of an RTU:
- An RTU typically uses less energy, since it’s assembled and configured in a factory under optimal conditions.
- As the RTU is mounted on the roof, it does not take up any interior space.
- Installation is typically easier. Only the interior ducts need to be installed separately.
- Diagnostics and repair may be easier, as all the components are in one place.
Additional Commercial Inspector Resources:
- Central Plant Systems and Chilled Water Systems
- Commercial Property Inspection Technical Class (Live)
- Hiring Independent Contractors