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.
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
Post Falls, ID — C-RTU installation
Renton, WA — PVC condensate line installation at a 2% slope utilizing conventional hangars and unistrut supports.
Bend, OR — Condensing RTU with evaporative air conditioning feedwater piping visible.
Post Falls, ID — Condensate neutralizer and overflow by-pass located just before a kitchen floor drain.
The following resources were developed to help market actors across the supply chain learn, leverage, and share insights on C-RTU technology.
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.