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Condensing Gas Rooftop Units (C-RTUs)

Rooftop units (RTUs) are commonly used in commercial applications due to their inherent convenience: RTUs package heating and cooling equipment together in a space that doesn’t take up precious real estate and is still accessible to technicians. Condensing rooftop units (C-RTUs) have recently entered the commercial RTU market, providing the benefits of non-condensing RTUs at much higher efficiency levels and lower operating costs. In fact, condensing furnaces can achieve over 90 percent AFUE—a big upgrade when compared to traditional gas furnaces that range between 78- and 82-percent AFUE.

How It Works

The illustration to the left demonstrates how C-RTUs work when installed on the roof of your commercial building. 

Condensing rooftop units (C-RTUs) work similarly to traditional gas RTUs with one crucial difference: the condensing systems use a secondary heat exchanger to extract heat from the flue gases—heat that would have otherwise been lost.

Note: This drawing is for illustration purposes only and does not represent the sizing or depth of the system or frame for all manufacturers' products. Check with manufacturer for exact measurements and specifications.

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C-RTU Performance

To better understand system challenges and to evaluate field performance, user acceptance, reliability, and energy savings potential in the Northwest, BetterBricks partnered with local utilities and businesses to install and monitor four C-RTUs during the 2018/2019 heating season. 

The study found that C-RTUs have proven potential to achieve greater gas savings than standard efficiency units, including: 

  • Improved performance with 10-15% higher heating efficiency
  • Up to 11.5% reduction in gas energy usage

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The following resources were developed to help market actors across the supply chain learn, leverage, and share insights on C-RTU technology.

Featured Resources

Pro-Tips for C-RTU Installs

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What’s the difference between installing condensing (C-RTUs) and conventional gas RTUs? Mostly it’s about careful attention to condensate management. The condensing furnace in C-RTUs requires considerations for piping, pumps, neutralizers, and freeze prevention – otherwise there’s the risk that the unit will not function as efficiently as specified, and there’s a threat that the original equipment manufacturer (OEM) may not honor their warranty.

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Condensing Rooftop Units (C-RTUs) Bring Promise of Higher Efficiency and Reduced Building Operating Costs

Article

Rooftop units (RTUs)—HVAC appliances installed on building roofs—are commonly used in commercial applications due to their inherent convenience: RTUs package heating and cooling equipment together in a space that doesn’t take up precious real estate and is still accessible to technicians.

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Condensing Rooftop Unit Field Study Summary Report

Article

To better understand challenges and to evaluate field performance, user acceptance, reliability, and energy savings potential in the Northwest, NEEA partnered with local utilities and businesses to install and monitor four condensing rooftop units (C-RTUs). This report summarizes the field study results from those four units during the 2018/2019 heating season. For more detailed information and findings, view the C-RTU Field Study Final Report at: betterbricks.com/resources/condensing-rooftop-unit-field-study-final-report

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Ideal Building Candidate for Condensing Gas Rooftop Units

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Condensing Gas Rooftop Units (C-RTUs) are an excellent technology for commercial buildings to increase their HVAC gas efficiency levels. As with all technologies, some buildings are better candidates for C-RTU installation than others. Here are a few considerations to determine if your building could be a good candidate for C-RTUs.

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C-RTU Training Slides & Webinars

The following training presentations explored gas-fired C-RTU technology and its performance on commercial facilities. The trainings highlight the energy efficiency benefits associated with C-RTUs, while debunking current myths.

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