Understanding Packaged Rooftop HVAC Units: Key Components & Configurations
Understanding Packaged Rooftop HVAC Units: Key Components & Configurations
When it comes to heating, ventilation, and air conditioning for commercial buildings, Packaged Rooftop Units (RTUs) are one of the most popular and efficient solutions. Whether you’re managing a small restaurant or a large shopping center, RTUs provide scalable, compact, and reliable climate control.
At American Cool, Heat, Air & Commercial Refrigeration, we regularly design, install, and maintain these systems for businesses throughout Los Angeles, the surrounding areas, and the Coachella Valley.
In this article, we break down the essentials of RTUs, from their size and weight to their airflow configurations and energy-saving components.
What Are Packaged Rooftop Units?
RTUs combine all key HVAC components into a single packaged system mounted on a building’s rooftop. They serve a variety of commercial properties such as:
♦ Office buildings
♦ Restaurants
♦ Schools
♦ Retail stores
♦ Grocery stores
♦ Shopping centers
♦ Hotels and hospitality venues
Rooftop Units are available in a wide range of sizes, starting from small 2-ton units all the way up to massive 162-ton units like the Trane Intellipak™ 2. While most people are familiar with smaller 5- to 15-ton systems, it’s important to note that larger RTUs can be extremely long and heavy — comparable to parking multiple vehicles on the roof.
Why RTU Weight & Structure Matter
The significant weight of large RTUs means that structural support is a major consideration. For example, a 25-ton unit can easily outweigh a full-sized car. Before installing large RTUs, structural engineers must verify that the building’s roof can handle the load safely. This makes expert planning and professional installation critical.
Key Components Inside an RTU
While the cabinet size of RTUs may remain similar across tonnage ranges, the internal components scale based on the system’s cooling and heating capacity:
♦ Compressors: Larger units often contain multiple compressors and refrigeration circuits for better load management.
♦ Condenser Fans: The larger the unit, the more condenser fans are required — from two fans to as many as ten.
♦ Coils: Scaled to handle higher heat exchange loads.
♦ Filters: High-efficiency filters (such as deep bag filters) ensure clean air circulation.
♦ Dampers & Airflow Controls: Manage fresh air intake, return air, and exhaust.
Despite the size, the refrigeration cycle remains fundamentally the same across all RTU models. Larger units simply include more stages, more fans, and additional redundancy.
The Importance of Airflow Configurations
One of the most crucial aspects of RTU performance is airflow management. Depending on the building design, size, and ventilation needs, you may configure RTUs in different ways:
1️⃣ Supply Fan Only (Basic Configuration)
♦ Common in small buildings or single-zone systems.
♦ Economizers bring in outside air, but during 100% outside air cycles, internal building pressure can increase.
♦ Barometric dampers may help relieve pressure but aren’t sufficient for large spaces.
2️⃣ Supply Fan + Return Fan Configuration
♦ Ideal for ducted return systems with higher static pressure (>0.40” ESP).
♦ Return fan manages air returning from occupied spaces.
♦ Supply fan handles supply duct pressure only.
♦ Three sets of dampers modulate outside air, return air, and exhaust air depending on ventilation needs.
3️⃣ Supply Fan + Exhaust Fan Configuration
♦ Suitable for non-ducted return systems (such as attic returns) with low static pressure.
♦ Exhaust fan works in tandem with building pressure sensors to maintain neutral or slightly positive building pressure.
♦ As the economizer opens for fresh air, the exhaust damper or fan modulates to relieve excess air, preventing pressurization issues.
Energy-Saving Economizer Operation
Economizers play a key role in RTU efficiency. When outside temperatures allow, the system can enter 100% economizer mode:
♦ Return air dampers fully close.
♦ Outside air dampers fully open.
♦ Exhaust air dampers open to expel indoor air.
♦ Compressors and condenser fans can remain off, saving significant energy.
By bringing in cool outside air directly, economizers reduce compressor run-time and lower energy consumption, making them an essential feature for efficient commercial HVAC design.
Why Professional Design & Installation Matter
Selecting the right RTU configuration isn’t one-size-fits-all. It requires:
✅ Understanding your building’s unique airflow patterns
✅ Evaluating ductwork design and static pressure
✅ Coordinating structural engineering for heavy rooftop equipment
✅ Installing and commissioning complex damper, sensor, and fan systems
✅ Ensuring long-term efficiency and maintenance accessibility
Serving Los Angeles, Coachella Valley & Surrounding Areas
At American Cool, Heat, Air & Commercial Refrigeration, we’ve installed and serviced countless commercial RTUs across Los Angeles, Coachella Valley, Riverside, Palm Desert ,Rancho Cucamonga Orange County, and beyond. From smaller 5-ton systems to full custom rooftop installations with integrated economizers, return fans, and exhaust systems — we do it all.
If you’re planning a new rooftop HVAC installation, need professional maintenance, or want to optimize your building’s airflow and energy usage, we’re ready to help.
EXTENSIVE SERVICE COVERAGE FOR COMMERCIAL HVAC & REFRIGERATION SOLUTIONS
No Commercial HVAC or Refrigeration job is too small or too far for us. While our primary branches are located in Palm Desert and Rancho Cucamonga, California, we’re dedicated to reaching customers wherever they are in need.
Proudly serving cities across California, including Indio, La Quinta, Indian Wells, Bermuda Dunes, Thousand Palms, Cathedral City, Rancho Mirage, Santa Ana, Fontana, Moreno Valley, Glendale, Ontario, Garden Grove, Palm Desert, Irvine, Anaheim, Riverside, Palm Springs, and extending to Los Angeles and beyond. Your satisfaction is our priority, no matter the distance or scale of the project.
AMERICAN COOL HEAT AIR BRANCHES
PALM DESERT, CA
77564 Country Club Dr. #142,
Palm Desert, CA, 92211
RANCHO CUCAMONGA, CA
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Rancho Cucamonga 91730