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Commercial Air Conditioning, Commercial HVAC, Commercial Installations

What is an RTU HVAC System?

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Last Updated on April 8, 2019



Considering an RTU HVAC for your business?

If you’re adding or replacing heating and air conditioning equipment in a commercial space, your contractor may recommend an RTU HVAC unit.

What exactly is an RTU? It stands for “roof top unit.” So now you can guess that this type of HVAC equipment lives on the roof. It’s a self-contained unit that provides both heat and air conditioning for certain types of spaces.

Keep reading to learn more about the RTU HVAC system, and find out if it may be a good choice for your commercial space.

How is an RTU HVAC different from other HVAC systems?

We mentioned that an RTU HVAC unit lives on the roof. However, other types of HVAC equipment can also be installed on a roof, such as split-system air conditioning condensers, or water-cooled chiller systems. So what makes an RTU HVAC system different?

An RTU is sometimes called a “packaged unit” because it includes all the components of an air conditioning and heating system in one box:

  • an AC evaporator coil, which absorbs heat
  • an AC condenser coil, which releases heat
  • an AC compressor, the heart of the air conditioning system
  • a heat source
  • a fan to blow heated and cooled air through the ducts
  • an intake for outside air (to improve ventilation)

The RTU HVAC unit provides all the heating and air conditioning needed for your space. The heated and cooled air reaches different areas in the building via ductwork and registers. You’ll also have return registers to pull air back into the system.

Other types of HVAC systems have separate components. In an air-cooled split system, for example, the condenser is typically located outside, and the evaporator and fan are inside. Also, you’ll need a separate boiler or furnace for heat with a split system.

So why choose RTU HVAC? Here are some of the pros and cons:

RTU HVAC pros:

  1. They use less energy. That’s because all the components have been assembled and configured in a factory under optimal conditions, so the system works at maximum efficiency. That translates to lower utility bills for you.
  2. They don’t take up indoor space. Everything is on the roof, except for the ducts. You don’t need to waste expensive indoor space for air handling equipment.
  3. Installation is simpler (read = less expensive). Most of the job has been done at the factory. That’s why the overall RTU HVAC cost tends to be less than for other types of systems.
  4. Distribution may already be in place. If you are replacing an existing system, chances are you already have the existing ductwork.
  5. Faster diagnostics and repairs. Since all the components are in one place, it’s faster for HVAC technicians to diagnose problems and fix them. Again, that lowers your costs.

RTU HVAC cons:

  1. They require roof space and access. To install an RTU HVAC system, you’ll need relatively easy access to the roof, as well as space of the roof to install the unit. Remember that you’ll need to maintain the unit for years to come. If it’s difficult to get up there, that adds to the maintenance cost.
  2. It’s exposed to the elements. The entire system is exposed to high heat, extreme cold, wind, rain, snow, ice and pollution. That can take its toll over time.
  3. Possible animal infestations. Since everything is outdoors, and in a location that’s away from traffic and people, animals can make their way in and cause damage.
  4. They are not suitable for tall buildings. There’s only so far that conditioned air can move through ductwork and still heat and cool the building. RTU HVAC systems are best for buildings under 10 stories.
  5. Out of sight & out of mind. RTU HVAC equipment tends to suffer from neglected maintenance more than other types of systems. This can lead to breakdowns that interrupt business and shorten the life span of the unit.

Learn more about the importance of regular maintenance for an RTU HVAC unit: Rooftop HVAC Units: Out of Sight Shouldn’t Mean Out of Mind

Is an RTU HVAC right for your space?

RTU units are commonly used for large, open spaces such as warehouses, large stores and shopping centers. Single-story buildings are best suited, since the conditioned air doesn’t have to travel very far to the space. However, RTUs can be used in multi-story buildings as long they don’t exceed 10 stories, and there is accessible space on the roof and ductwork in place.

Another fairly common application for RTU HVAC systems is restaurant kitchens. In these settings, RTUs are installed as what’s known as a “make-up air unit.” Their function is to provide additional ventilation and conditioned air to replace air that’s vented out through high-powered stove hoods.
Learn more about make-up air units: Essential Equipment for Commercial Kitchens: HVAC Make Up Unit

Not sure if RTU HVAC is right for you? Check out this guide to learn about the different types of HVAC systems used for commercial spaces and what’s best for specific types of businesses: The Ultimate Guide to NYC Light Commercial Air Conditioning.

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