A mechanical drawing shows an HVAC unit with the designation 'RTU-3, 15 tons, 460V/3Ph'. What type of equipment is this?
Correct Answer
B) Rooftop unit
RTU stands for Rooftop Unit, which is a packaged HVAC system typically installed on building rooftops. The designation indicates it's unit #3 with 15-ton capacity and requires 460V three-phase power.
Why This Is the Correct Answer
RTU is the standard industry abbreviation for Rooftop Unit, which is a self-contained HVAC system designed for installation on building rooftops. The designation 'RTU-3' indicates this is the third rooftop unit in the system, while '15 tons' refers to its cooling capacity and '460V/3Ph' specifies the electrical requirements (460 volts, three-phase power). These units are commonly used in commercial construction because they save interior space and provide easy access for maintenance.
Why the Other Options Are Wrong
Option A: Residential thermal unit
While 'thermal unit' could describe HVAC equipment, 'Residential thermal unit' is not a standard industry term or abbreviation, and the 460V three-phase power requirement indicates commercial rather than residential application.
Option C: Radiant tube unit
Radiant tube units are typically gas-fired heating systems that use radiant heat transfer, not packaged HVAC units, and they don't use the RTU designation or require the electrical specifications shown.
Option D: Return terminal unit
Return terminal units are components within HVAC ductwork systems that handle return air, not standalone packaged units, and they wouldn't have tonnage ratings or high-voltage electrical requirements.
Memory Technique
Remember 'RTU = Rooftop Unit' by thinking 'Roof Top Up' - these units literally sit up on the roof top of buildings.
Reference Hint
Florida Building Code - Mechanical, Chapter 5 (Exhaust Systems) and Chapter 6 (Duct Systems), or HVAC equipment specifications section
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