The Embarcadero Center in San Francisco, California, is a commercial complex consisting of four office towers. This development was a collaborative effort involving Trammell Crow, David Rockefeller, and John Portman. Construction began in 1971 with Tower One, and the final addition, Embarcadero West, was completed in 1989. This expansive complex spans 4.8 million square feet (445,900 m2) and houses offices for approximately 14,000 individuals. It also features mixed-use spaces that cater to retail, dining, entertainment, and cinema needs.
However, a significant issue arose in 2020-21 when a bank of six AERCO BMK 5.0 condensing boilers was installed in the penthouse of 1 Embarcadero Center to replace the aging firetube boilers. Initially, the plan was to vent these boilers through vertical sheet metal panels on the sidewall. Unfortunately, after commissioning, it became apparent that the steamy boiler exhaust resembled smoke billowing from the penthouse windows, prompting monthly calls to the fire department to extinguish what appeared to be a fire.
In 2022-23, ENERVEX Northern California proposed an alternative solution. They suggested configuring the six boilers into two banks of three each and routing them to the roof. The boiler room's tight quarters made it impractical to run individual flues to the roof, primarily due to Aerco's venting guide requirements.
The new design called for coring through the ceiling/roof to establish two common flues, then navigating them around equipment and electrical panels. This particular level is enclosed by a ~10' concrete parapet, concealing cooling towers and other mechanical equipment. Consequently, the flues had to be directed one level higher to the building's rooftop, which featured a grated floor partially covering the mechanical equipment.
To address this challenge, TDF fans were installed vertically on stands custom-fabricated by the contractor, and termination cones were fitted at the outlets. The draft is effectively controlled by EBC31 Modulating Exhaust Controls.