rooftop versus internal furnace

This vs. that: Rooftop HVAC systems vs. furnace/condenser systems

Comparing HVAC options? Here’s what you need to know

HVAC systems can account for more than a third of the energy used by commercial buildings, making the selection of your HVAC unit essential to the bottom line for your business. Selecting between two common types of HVAC systems, rooftop units or an internal furnace/condenser system, has a lot to do with your organization’s heating and cooling costs, not to mention installation, maintenance and repairs.

Many factors feed into the decision of what kind of unit will best serve your needs, so let’s take a closer look at the differences between rooftop units and internal furnaces/condensers.

What you should know about rooftop units

  • They’re commonly known as pre-packaged rooftop units, providing both heating and cooling for the conditioned space. They are located on the roof of the building, connected to supply and return-air ductwork distributed throughout the conditioned space.
  • Rooftop units tend to be compact. They are often found in low-rise commercial properties and are convenient for homes with a limited footprint or yard space.
  • A rooftop unit doesn’t take up valuable interior space. It works well in buildings too small to accommodate an interior coil or air handler.
  • There is almost always room for roof installation, as rooftops are generally unused space, but rooftops can only be installed on low-slope flat roofs.
  • Rooftop units may create less bothersome noise as the compressor is located on the roof, away from work areas.
  • Installation may be easier with a single access point, although hoisting is required to set the unit on the roof, and roof access is required for installers.
  • The units are often more accessible than internal furnaces/condensers, simplifying repairs and maintenance for technicians, although roof access is required.
  • Because the heating and cooling components are housed in one cabinet, maintenance and repairs are often easier, faster and less expensive with a rooftop unit.
  • Depending on the municipality in which your project is located, the rooftop units may require screening at each unit’s perimeter and/or increased building parapet height to screen the rooftop units from view.
  • Rooftop units require structural reinforcing of the roof structure to accommodate their weight, which needs to be coordinated early during the design phase.
  • Rooftop units set on roof curbs, which require larger penetrations through the roof, require additional roofing work during initial installation and additional roofing maintenance long term.
  • Depending upon the specific building layout and level of control desired, multiple rooftop units can be scattered throughout the building roof for optimum comfort and control.
  • Assuming structural reinforcing can be added and ductwork routing is accessible, rooftops units can be added easily to an existing building that is being repurposed.
  • Rooftop unit use is primarily limited to low-rise buildings (one to two floors tall), as use in mid-rise and high-rise buildings is impractical.

What you should know about internal furnaces/condensers

  • Furnace/condenser systems consist of two separate cabinets, one interior and one exterior, that work together to provide heating and cooling.
  • Furnace/condenser systems are the most common systems installed in the U.S., primarily due to their common use in residential home construction.
  • Furnace cabinets are typically housed in a mechanical closet at the building interior, which takes up more interior space than a rooftop unit. These are suitable for properties where space is not at a premium.
  • Condenser cabinets are installed at the building exterior, typically ground-mounted adjacent to the building or on the building roof.
  • Depending on the municipality in which your project is located, condensers may require screening to hide them from view.
  • An internal furnace/compressor may be noisier to occupants if sound insulation is not incorporated, as the compressor unit is located in the interior of the building.
  • Internal furnaces/condensers are often placed in small spaces or areas that can be more difficult to access. This can lead to higher repair, maintenance or replacement costs.
  • Depending upon the specific building layout and level of control desired, multiple furnace/condenser systems can be scattered throughout the building for optimum comfort and control.
  • Assuming there are locations for condensers, furnace/condenser systems can be incorporated into low-rise buildings, mid-rise and high-rise buildings.

Deciding between a rooftop unit and an internal furnace/condenser

It’s just one of the thousands of decisions you have to make about your project, but when it’s time to choose between a rooftop unit and a furnace/condenser system, having the right team of experts at your side is essential. As a design-build firm, our entire team is invested in your project’s success, from start to finish. So from the big decisions to the seemingly smaller ones, nothing is left to chance, and you can feel secure in the fact that we’re all working toward your vision.

We work with developers throughout the Wisconsin, Minnesota and beyond, and we’re here for you. Want to learn more about how the design-build model of construction can help you? Contact us, and we’ll help move your commercial construction project toward reality.