Limitations & Construction Issues:

 

Rooftop units are commonly used but have the following limitations for construction, usability and versatility:

 

• Can be costly in the initial stages of construction and over time for repairs due to the multiple parts and all-inclusive workings

  • If a part is damaged, replacing them is not easy because the system components are packaged tightly within the frame.

  • Prepackaged systems also have limited options for replacement parts outside of the company of manufacture due to limited comparability between different company systems and designs

 

• There also is maintain and repairs due to the unit being outside and exposed to outdoor eliminates such as rain, snow and leaves.

  • The lifespan of a RTU is shorter than indoor systems because of its exposure to the outdoor eliminates mentioned above.

 

• Easily installed with new construction, but existing structures cause difficulty due to the fitting of the unit with existing ductwork and/or HVAC openings. RTU provide a high volume of air supply to the building, which may need larger ductwork than existing, which is a costly expense.

  • Large ductwork also can warrant issues with the aesthetics of a building’s design, and can create the need for changes in the design of an existing building

 

• Air handlers in general can be very heavy due to their large size and components. There needs to be adequate support underneath a unit and especially under a RTU as the loads from the RTU need to be carried throughout the building from the roof down to the foundation. In one-story building this is not as difficult, but in multiple story buildings, this can pose challenges to design and cause the need for large beam sections which in turn are a higher cost.

 

• Standard units do not have the fan capability to supply air for a building taller than 5 stories as mentioned above in Typical Uses. If the building is taller than 5 stories, multiple units need to be used to provide enough heating and cooling for the space.

 

• Any AHU are limited by the lack of control they provide to the individual spaces. This is why they are used for commercial spaces which do not have many rooms that each need to be controlled individually. In a residential instance, a RTU or AHU would use special controls to cater to the needs of the home.