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.


Commercial HVAC system Inspection


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.


Rooftop Unit Inspection RTU


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.




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