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updated 12/9/22

It’s a common sight: large, commercial rooftop HVAC units sitting on top of a building with ducting and pipes snaking all over the roof to various points of entry into the interior. Not every business relies on these units, though; it is just as easy to spot split systems in use at many establishments, especially smaller operations such as restaurants. Does one system have an advantage over the other?


Commercial Rooftop HVAC or Split-System – Which is Better?


If you own or manage a commercial building, then you’re probably already aware of just how important it is to pick the right HVAC system. Climate control is a must for any business, especially ones that frequently host customers inside, which means you’ll need to have some kind of HVAC unit before you can use the building. HVAC systems are also frequently the biggest electricity drains in any commercial building, so picking the right one can save you a ton of money – or the wrong one can leave you with sky-high power bills every month.


While some smaller commercial spaces can get away with mini-splits or other, more efficient units, the vast majority of buildings will have a central forced-air system of one kind or another. The two most common types of HVAC configurations for commercial use are packaged rooftop units and split-system units. Each of these two options has its own advantages and disadvantages, and choosing between them can be a little tricky. It can be difficult to know where to start, especially since it’s such an important decision that can have serious ramifications for the comfort and energy efficiency of your building.


That’s why we decided to put together this blog post with some basic information to help you decide which HVAC system is best for your building. We’ll talk a little bit about the most pressing needs for commercial buildings as well as go over the advantages of both packaged rooftop units and split-system HVAC units.


HVAC 101 Everything you need to know


Top Needs for Commercial HVAC in the Santa Rosa Area


As a general rule, the first thing you should consider when purchasing an HVAC unit is the climate in your area. After all, there’s really no sense in paying for a unit that you won’t ever have to use. Santa Rosa, for example, has temperatures that reach both hot and cold extremes during the year, so commercial buildings in this area need an HVAC system with both heating and cooling capabilities. However, a building in Arizona likely won’t need a heating unit, so owners and managers there can make air conditioning a priority.


For a long time, businesses and homeowners had to install two different units if they wanted both hot and cold air coming through the vents – generally an air conditioner and a furnace. However, heat pumps that can switch back and forth between heating and cooling the air are becoming increasingly popular due to their efficiency and compact nature. Heat pumps can come in both packaged and split-system forms, so you’ll still have to decide which of these two options is the best one for your needs.


Distribution is sometimes a difficult question for residential HVAC systems, but commercial buildings almost always use ducts to distribute warm or cold air through every room. This is called a central or forced air system, and it’s the most common type of HVAC set-up in North America. Some smaller businesses can use ductless HVAC units to save a little money on their electricity bills, but the cost of installing air handlers in every room can easily become out of hand for many building owners. For now, ducted HVAC is the best option for the vast majority of commercial spaces.


On the flip side, temperature control is often a trickier proposition in commercial HVAC systems than in residential ones. Most homeowners have a single thermometer that controls the temperature for the entire house, but that can be extremely wasteful in a commercial context. For this reason, many commercial HVAC systems are zoned, which means they’re split up into a few different sections, each one with its own temperature control system. This allows building managers to save electricity by turning the climate control off for sections of the building that aren’t currently in use. Keep in mind, however, that you might need to pick up a separate unit for each zone, depending on the size of the building.


Size is also an important consideration for commercial HVAC units. These units are measured in “tons,” which refers not to the physical size of the unit but rather its heating or cooling power. An HVAC contractor will be able to take a look at your building and do the calculations necessary to size your system, so we won’t go over all those factors here. For some context, however, residential air conditioners tend not to go much higher than 5 tons, while commercial units are often sold in 10, 20, or even 50-ton models. It’s extremely important to make sure your HVAC units are properly sized, so make sure to work with your contractor throughout the process.


5 Reasons to Install Rooftop Commercial HVAC Units


While the most common type of packaged HVAC unit is a window air conditioner or heat pump, commercial buildings use larger versions often called RTUs (Roof Top Units). As the name suggests, these units are typically placed on top of the roof where they can connect easily to the ductwork inside the building. The main thing that separates packaged RTUs from standard split-system units is that everything is bundled up into a single unit instead of being broken up into two. They’re typically encased in a heavy metal casing to protect the parts inside from the weather, making them very resilient. RTUs are very popular for commercial buildings, and here are a few reasons why:


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Modularity and Flexibility

One major advantage of a rooftop unit is that they’re very modular and easy to swap in and out. That gives you some flexibility to modify your HVAC system later on by adding new units or swapping them in for older ones. As an owner or manager of a commercial building, you always need to have the possibility for growth in mind as you make decisions. A residential HVAC system is easy since the household won’t change and grow all that much throughout the years, but ideally, a commercial space should be equipped to handle growth from the businesses based inside. Whether it’s an addition of new employees, a change of tenants, or even construction on a building addition, you can always just plug one or two new RTUs into the existing system without issue.


Because the units are all so easily interchangeable, RTUs also make repairs fairly simple. If you need to repair one unit, the others can easily pick up the slack so the employees inside the building don’t even notice the difference. They’re also easy to repair since all the parts are in the same space, making it simple to poke around inside.


Compactness and Size

This is probably the most obvious advantage of a packaged rooftop HVAC unit. Split-system units can take up a lot of room, which makes planning difficult when space is at a premium. RTUs, on the other hand, hold all the components in a single, compact casing. You can easily line up several RTUs next to each other without taking up a ton of space, as long as you leave enough room for your maintenance staff or hired HVAC technician to work on each unit individually. Packaged HVAC units also don’t take up any space inside the building other than the space already filled by the ductwork, which means you’ll have plenty of room to grow inside.


A roof is also an ideal place for HVAC units since, well, there’s really not much else up there. Rooftops are essentially wasted space for most buildings since there are very few things that can actually be kept up there in the weather and heat from the sun. However, packaged rooftop HVAC units are designed to be kept outside, so they’re more than hardy enough to survive a little rain and wind. Placing them up on the roof frees up space on the ground surrounding the building, which you can fill with paths, outdoor eating areas, or aesthetic objects like shrubs and trees.


Security and Quiet

Placing your HVAC units up on the roof not only frees up space on the ground but also makes sure the units are tucked away out of the most public parts of your building. This is great for security purposes since the roof is so difficult to access without a key to the building. HVAC units are often targeted by vandals or scavengers due to the aluminum and copper inside, but placing them up on the roof puts an obstacle between the units and any would-be attackers.


Keeping the units up on the roof also means that the sound of the system running is kept as far away from any employees inside as possible. Commercial HVAC systems have to be extremely powerful in order to control the climate inside a building that size, which means they typically run very loud. It can be extremely difficult for anyone to work when the sound of the AC blower fan is right by their ear, so it’s always a good idea to tuck those units away to avoid distracting the workers in the building.


Price and Ease of Installation

Naturally, price is always going to be a major factor when making decisions like these. Most building owners tend to come in with a fairly strict budget in mind when picking out HVAC units, so it’s always a good idea to take a look at some less expensive options before making up your mind. As a general rule, a packaged rooftop unit is going to be cheaper than a comparable split-system unit, typically by a few thousand dollars. For reference, you can pick up a 5-ton packaged RTU heat pump online for about $3600. From the same source, 5-ton split-system heat pumps range between $4500 and $7500, based mostly on the energy efficiency of each individual unit. When you keep in mind that you’ll likely need several units of that size, suddenly you’re looking at savings approaching $10,000.


You’ll also save a little money on installation costs if you opt for a packaged RTU. These units are significantly easier to install because they’re all in a single casing, which means less time and labor on the final bill. Saving money is a good thing, and cost is always a relevant concern.



Because there’s so much open space on the roof of most buildings, placing your HVAC system up there means you have the option of installing much larger and more powerful units. While mini-splits and most smaller split-system units won’t be able to handle the heating and cooling for an entire commercial building, you can easily find rooftop units powerful enough to keep everyone inside comfortable year-round. It’s worth noting, however, that bigger doesn’t always mean better. An HVAC unit that’s too large will be inefficient and break down faster than one perfectly sized for the space.


5 Reasons to Install Split-System Commercial HVAC Units


Split-system HVAC units are the standard for residential buildings and are popular for commercial purposes as well. The biggest difference between these units and RTUs is suggested by the name – rather than keeping everything in a single box, split-system air conditioners and heat pumps split the components into two separate units. That might sound like a disadvantage, but there are reasons why splitting the coils can be a benefit for your HVAC system. Here are a few reasons why you might want to install a split-system air conditioner or heat pump in your commercial building:


Energy Efficiency

When we rate the energy efficiency of any given HVAC system, we use a measurement called Seasonal Energy Efficiency Rating, or SEER. In technical terms, SEER is the ratio of cooling output in BTUs to energy usage in watt hours. The higher the SEER, the more energy-efficient the unit is. You can actually use this rating to do your own math and figure out how much power a unit will use in any given period of time, although that’s likely overkill. The most important thing to remember is that you want a system with a high SEER if possible.


For the most part, a split-system heat pump or AC unit is going to be more energy-efficient than a comparable RTU. Packaged units tend to have SEERs ranging between 10 and 18, while split-system units start out at 13 or 14 and reach the 20s. When you have units running all day to keep workers and customers comfortable in your commercial building, even relatively small differences in energy efficiency can have a significant effect on your monthly electricity bills. However, that doesn’t mean a split-system unit is always more efficient – it still depends on the unique building in question.


Easy Access and Maintenance

This factor will depend pretty heavily on the specifics of your building. In a general sense, a rooftop is often going to be a less convenient space to access than elsewhere in the building, which means RTUs can be a bit of a pain to service. This isn’t necessarily the biggest deal for your regular yearly appointments, since technicians are used to working in inconvenient spaces, but it can be a problem if you have regular maintenance staff employed at the building. Rooftops also offer more danger and require a little extra safety training to make sure nobody slips or falls off.


Split-systems are split into two units, which can be a pain, but both units are typically in a fairly accessible place. The indoor unit, sometimes called an air handler, holds the evaporator coil and the blower fan. The outdoor unit holds the compressor and the condenser coil. In most cases, the outdoor unit of a split-system heat pump or air conditioner is kept outside on the ground, generally tucked up against the side of the building. This makes it significantly easier to access than a rooftop unit – as is the air handler, which is typically just inside at the entrance to the ductwork.



Even though RTUs are manufactured to be tough and resistant to the elements, there’s only so much you can do to protect the parts inside. Placed outside on the roof, they’re exposed to the sun, wind, rain, and anything else the elements can throw at them. They’re also more vulnerable to damage from animals, which often try to curl up inside the unit because of the heat. Pests like squirrels can chew on the wiring, damaging the unit.


Split-system units, on the other hand, are generally more protected. The air handler is always kept safely inside the building, which keeps it safe from weather, pests, and any potential vandals. The outdoor unit is somewhat more vulnerable, although the building itself does provide a certain amount of shelter from the elements. Regardless, it’s much easier and cheaper to replace parts of the outdoor unit than to replace the entirety of a rooftop packaged unit. The protection from the elements also means that split-systems tend to last for a lot longer than packaged units, so you won’t have to replace them as frequently.



Whether or not a split-system or a RTU is better for you will depend on the size and shape of the building in question. Split-system units are often better for smaller buildings, since they can easily scale down and be extremely energy-efficient. RTUs also weigh significantly more than either unit of a split-system AC or heat pump, restricting them to buildings large enough to hold their weight without damaging the roof. This is why rooftop units are very rarely seen on houses and other residential buildings that could be damaged by the heft of the unit itself.


There are also a few different options for split-systems in smaller commercial buildings like storefronts or work trailers. Ductless mini-splits have become increasingly popular for their convenience and superior efficiency, although they’re expensive to purchase and install in large spaces. Mini-splits skip past the ductwork, instead blowing air directly from the air handler into the room. A full mini-split system generally includes an outdoor unit with the compressor and condenser coil connected to multiple air handlers, each with its own evaporator, blower fan, and thermostat. This makes them efficient and ideal for zoning, since each air handler covers a small section of the building, often a single room.


Air Quality

Typically, the air circulated by a rooftop HVAC system will be taken from both inside and outside the building, allowing fresh air to cycle through. This prevents the air from becoming stale, but also introduces potential contaminants from outside the building. Split-systems, on the other hand, tend to only cycle the same air from inside the building over and over. To prevent the air from becoming stale, split-system units use air filters so they’re constantly removing dust and other particles from your building’s air supply. This can be hugely beneficial to the air quality inside. However, you have to be careful to stay up to date with the air filter maintenance schedule. Filters typically need to be either swapped out or cleaned about once a month, and leaving a dirty filter for too long can cut down on airflow, forcing the unit to work harder and wear down faster.


Split-system air conditioners and heat pumps also act as dehumidifiers as they run, constantly drawing moisture from the air and redirecting it outside through a drain line. This helps keep the temperature low while also making the air drier and easier to breathe. This is especially useful in humid areas like the southeastern US.


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Santa Rosa’s Top Choice for Commercial HVAC

If you’re thinking about installing a new HVAC system in your commercial building, your journey should start with a trusted and licensed HVAC contractor. Together, you can explore your options and figure out which type of system will best fit your needs. If you’re in Santa Rosa or the surrounding area, feel free to give Valley Comfort Heating & Air a call and we’ll be more than happy to visit your building, help you find the right HVAC system, or even just answer any additional questions you might have.