By Catie VanWormer, P.E. LEED AP
In one U.S. wastewater treatment plant, a firebox-style boiler installed in 1999 began failing due to a tube leak. The boiler was equipped with a dual-gas-capable burner, firing both natural gas and digester biogas in alternance. In 2015, the burner and gas trains were upgraded; however, the boiler continued to deteriorate.
With environmental sustainability as a key goal, city administrators wanted to replace the boiler with a more reliable and efficient model. They contacted Cole Industrial, headquartered in Lynnwood, Wash., for assistance.
Cole Industrial recommended the Cleaver-Brooks ClearFire®-CE (CFC-E) condensing hydronic boiler due to its operational efficiency, quick-ship availability, and reliable operation. The CFC-E achieves up to 99% efficiency with less than 20 ppm NOx emissions as standard. It features dual-temperature returns, enabling maximum operating efficiencies in a variety of system applications. There are no flow limitations to consider and no need to satisfy multiple boiler design constraints, allowing for system engineering flexibility.
The city was motivated to move forward with the boiler replacement, and the supervisor went to the mayor and city council to procure short-term funding with an emergency-status project in hand. In one day, a city contract was delivered, reviewed and signed.
Quick delivery of the CFC-E boiler from the Cleaver-Brooks stock program allowed the Cole team to demo the current system, deliver, install and commission the new boiler, and recover thermal input to the city’s wastewater digesters before they dropped to critical temperatures of 85 F (29.4 C) and below. This is the point at which the sewage-eating microbiological “bugs” will start dying off, and the system will become anoxic and septic, requiring a major expense to haul out the affected waste. Plant personnel must then locate bugs from a nearby wastewater treatment plant, seed the digesters, and slowly rebuild the biological base for them to recover and operate normally and at capacity.
The new exhaust stack arrived shortly after the CFC-E boiler. Because the new condensing boiler was replacing a noncondensing boiler, upgraded materials were required for the stack. This was not a problem for the experienced Cole team.
The CFC-E’s compact design and 3-inch side clearance made it easy to move into the boiler room. Designed for flexibility, the boiler offers alternate flue gas connection locations to accommodate different room layouts and is versatile for direct-vent or room combustion air. In addition, the CFC-E is suitable for variable-flow primary or primary-secondary applications alike.
On the first day, the old boiler was demolished and staged for removal. Ancillary work continued into day two, and by day three, the new boiler was set in place.
Installation of the CFC-E was simple due to the following factors:
- Inherent O2 trim (no moving parts)
- Integrated controller
- No housekeeping pad required (500 to 2500 MBH)
- BMS integration with built-in BACnet MS/TP support
By day six, the boiler was fully piped into gas, water and stack connections and wired by a city-provided electrical contractor. The boiler was commissioned on day seven. The hydronic systems were then back online, and the bugs started getting comfortable again after experiencing a drop in temperature to about 89 F (31.6 C).
With some room, but not much to spare, the city’s plant operations staff slowly started bringing digester temperatures back up to the 99 F (37.2 C) sweet spot, and the systems smoothed out and have been working well ever since.
The entire project, including demolition, took only seven days. The final handoff to the customer was completed in just 13 days. Worth noting, the wastewater treatment plant supervisor had been on vacation during the project. His staff wanted him to return to a successfully completed project, and the team made it happen.
Maintenance personnel appreciate the fact that ongoing boiler service and inspections are now easier due to the CFC-E’s hinged top assembly and simplified gas train. In addition, the duplex stainless-steel construction of the CFC-E ensures durability and longevity of the boiler for years to come.
Beginning January 1, 2025, commercial gas-fired boilers in Canada with input ratings between 300,000 BTU/h and 10,000,000 BTU/h must meet a minimum energy performance standard (MEPS) of 90% thermal efficiency. At up to 99% efficiency, the Cleaver-Brooks CFC-E boiler far exceeds that requirement.
To learn more about the environmentally friendly, quick-ship and easy-to-install CFC-E condensing hydronic boiler for design-build or emergency replacement, visit www.cleaverbrooks.com/part-of-the-team.
Catie VanWormer, P.E. LEED AP, is vice president of modular products for packaged boiler systems at Cleaver-Brooks. Catie works directly with owners, architects, engineers, contractors and manufacturers’ representatives on highly complex project specifications and product selection. An expert in hydronics and optimizing boiler system performance, Catie has authored numerous articles for industry publications and journals and is frequently tapped as a speaker.