Gregory Rochlin was completing a window preservation project at Boston’s historic Faneuil Hall in 2015 when city officials asked him to assess the condition of the mechanical attic in the public building. Rochlin climbed a narrow ship ladder to access the space. When he arrived, he was shocked to find air handlers the size of Volkswagens stuffed into an attic reminiscent of a submarine.

When asked what it would take to replace the 25-year-old mechanical system before its service life expired in 2020, he was dumbfounded. “My first reaction was ‘You cannot be serious,’” says Rochlin, a senior project manager for CSS Architects Inc.

For starters, Rochlin could not figure out how anyone had squeezed five 9-ft-long by 7-ft-wide air handlers, each 4.5 ft tall, through the attic’s 2.5-ft by 6.5-ft door opening. That mystery and others were eventually solved by sleuthing and lots of head-scratching, resulting in a $3.8-million mechanical systems upgrade that is nearing completion in a building that has served as a marketplace and meeting hall since 1742.

Initially, it also was unclear how during a 1990 modernization, which involved installing the building’s first elevator and cooling systems, crews had installed the heating, ventilating and air-conditioning (HVAC) equipment in such tight confines. But it became apparent that crews had carried in the equipment in pieces and assembled the units in place, “like a ship in a bottle,” Rochlin says.

The 1990 modernization complicated the current work. The earlier project required concealing air handling equipment in the basement and attic “to preserve the building’s appearance,” Rochlin says. The 1990 installation “presented enormous challenges” related to servicing  or replacing this equipment, Rochlin says. 

For the current upgrade, the team was originally directed to replace all of the existing mechanical equipment. But removing the equipment from the attic was impossible, Rochlin says. Designers considered temporarily removing the roof so the units could be picked out by a crane, but that approach turned out to cost too much.

The breakthrough happened when CSS contacted the original air-handling equipment supplier, PACE, which had been acquired by Johnson Controls. JC, which found the original shop drawings, said the equipment could be rebuilt by replacing the components inside the units’ steel enclosures, says Rochlin.

In addition, the work in the mechanical attic has helped preserve military artifacts housed immediately below in the fourth floor museum of the Ancient and Honorable Artillery Co. of Massachusetts. Before the work, there was concern that heating and cooling coils might leak and damage the artifacts in the 3,400-sq-ft museum space. To avoid leaks, the new mechanical units are equipped with sensors that can automatically shut down leaking units and digitally notify the appropriate city personnel.

CSS’s job was to design the upgrade that eliminated building code conflicts related to the 276-year-old landmark. “It’s not just a mechanical contractor coming in here taking stuff out and putting stuff in,” says John Savasta, CSS president. “Because it’s [a] historic building, there was a lot of sensitivity [about] how we did these things.”

 A focus of the project was the replacement of the manually controlled, and difficult to temper, forced hot air and radiator heating systems—and some of the building’s 100-year-old piping—with a modern hot water system. Crews installed upgraded humidifiers, hot water heaters, a heat exchanger and air-conditioning ductwork along with new chilled and hot water piping.

“The challenge was to replace all this equipment with minimal disruption ... to one of the most important buildings in Boston,” says Rochlin.

Fast Lane

The city originally requested the building remain occupied for the duration of the project. But that approach would have taken two years and doubled the project cost, Rochlin says.

Crews completed the bulk of the fast-tracked upgrade of the HVAC equipment and fire alarm systems during a four-month building closure during the winter. Currently, workers are finishing installing insulation, balancing the air flow for optimal air exchange and fine-tuning the computerized energy-management system that is linked to a control room in City Hall, 0.2 mile away.

The key to completing substantial construction for the design-bid-build project in just four months was awarding the work last August, about five months before construction was scheduled to begin, says Jim McGaffigan, Boston’s project manager in the property and construction management department. The construction documents required the general and mechanical contractor, J.F. White Contracting Co.—which declined to comment on the project—to purchase all of the equipment before the city turned over the building to the contractor on Jan. 18.

Bidding the work early “allowed sufficient time to investigate the building more completely and develop an aggressive, but attainable, construction schedule,” McGaffigan says.

It also helped that CSS’s contract was awarded about 22 months before construction started, he adds.

In addition to the accelerated schedule, there were several site and locale constraints. Working in the middle of Faneuil Hall required significant coordination. The main staging area, at only 4,500 sq ft, meant just-in-time deliveries, for instance.

The adjacent Faneuil Hall Marketplace—which includes 100 restaurants and shops—continued operating during the project. All work had to be done around the market, often crowded with visitors.

The heating system for the 38,200-sq-ft hall was disabled for most of the winter. The workaround was 16 portable 15-KW electric heaters scattered through the building.

Workers removed motors, hot- and chilled-water coils and associated controls like a “bucket brigade,” says McGaffigan. The effort boiled down to “passing the parts from the back to the front of the building, trying to stay out of one another’s way,” he says.

Once crews had removed the existing components, the team installed new heating and cooling coils, motors, belts, piping and controls for the five upgraded air handlers, which range in capacity from 4,500 cu ft per minute to 7,000 cfm.

With the attic only able to accommodate five workers at a time, the team used solderless pipe fittings to avoid having to have a fire watch on hand.

Contractors were unable to carry all of the equipment into the building by hand. Crews used a crane to hoist a 800-ton air handler and maneuver it into the building through the bell tower louver. The early-morning blind pick lifted the unit in four separate sections through the 6-ft by 4-ft opening.

An extension platform erected through the louver opening cantilevered over the roof. This allowed landing the sections onto the temporary platform without touching the building facade. Once in, crews assembled the air handler in its final resting place in the bell tower.

Pipe Chase

The original program also called for contractors to replace 28-year-old steel and cast iron pipes in two main vertical chases constructed in 1990. The chases carry steam, hot water and chilled water from the second floor to the attic. When the team dug into the chases, workers discovered conduit and ductwork not shown in the 1990s design plans.

Replacing the existing pipes would have required a “substantial amount” of demolition work, Rochlin says, including on the Great Hall’s ceiling and molding. “The cost and time to do this would have been beyond the project time frame and budget,” he added.

Luckily, the samples from the pipes tested at a lab determined that most of the pipes were “as good as the day [they were] made,” Rochlin says, noting that they salvaged 1,400 linear ft of piping.

It is unclear how much money was saved by retaining the pipes because the city hasn’t approved a final change order.  “We are close to an agreement” with J.F. White, says McGaffigan. 

Everyone took great pains to protect the historic building, its artwork and its adornments, most of which were protected or stored on site during the work.

The Boston Arts Commission covered all the hanging artwork in plastic, including the painting above the Great Hall stage depicting Daniel Webster speaking in the Old Senate Chamber in Washington, D.C.

The contractor protected wood floors with plywood and fiberboard. The museum’s more than 2,000 artifacts were stored in three sheds on site.

Workers also painstakingly repaired any inadvertent damage to the historic fabric. For example, to meet the state’s Architectural Access Board’s accessibility requirements, a fire alarm pull in the Great Hall had to be moved below what the team originally thought was wood molding. When they cut into the wall, however, they realized it was plaster. A plaster subcontractor restored the molding. 

Also, a dilapidated wheelchair lift in the Great Hall wasn’t up to modern standards. The lift was stored at the base of a narrow stairway behind the stage that doesn’t have the proper width or headroom to comply with code.

The team procured a $44,000 custom-fabricated wheelchair lift designed to fold up next to the stage when stored. Installed on time despite a two-month lead time, the lift, rated at 600 lb, was connected to  structural steel, added in 1890.

A steel-plate substructure was set in the floor. An “uplift” force was created by torque required to raise the lift, says Roger Hobeika of the structural firm that bears his name.  “We through-bolted the plate to the [steel] beam in the floor to take the uplift force,” he says.

Crews removed the more than 100-year-old steam radiators and associated piping, which were leaking at the fittings and valves, from the first and second floors leading into the great hall. To avoid changing the appearance of the wood radiator covers with stamped metal grills, the team custom-built hot water radiators with fin tubes “stacked two high” to fit behind the existing covers, Rochlin says.

Workers also had to replace and match an exposed hot water radiator that “needed to be larger than the existing unit to get the heat output because it was hot water and not steam anymore,” says Jerimy Moran, a senior mechanical engineer at BLW Engineers Inc.

Moisture Control

Another problem the team was tasked with solving was preventing moisture from entering the uninsulated building, which is located about 800 ft from Boston Harbor. With a constant stream of tourists entering four wooden doors to a first-floor indoor market, condensation formed on exposed and uninsulated ductwork during the summer. The condensation dripped onto the vendors, including food-service stalls.

The team corrected the problem by replacing the existing ductwork with internally insulated ductwork that maintains the original ductwork’s appearance. Additionally, the Eastern White Pine wooden doors were repaired off site. To keep moist air at bay, the team added wood to the doors to improve their seal to the door frame. Crews also installed stronger air curtains above each door.

There was also damage from water entering through a fake chimney installed on the roof during the 1990 modernization to serve as an elevator shaft vent. The chimney was needed because there was no space to build an elevator shaft penthouse.

To solve the leak, the team created a modified copper chimney cap with a hood to hide a custom-fabricated motorized damper. The damper keeps water out while simultaneously venting the elevator shaft. Crews had to do this “without making it look different” than a matching chimney on the other side of the roof, says Rochlin.

Water entering the elevator didn’t concern the team as much as protecting the Ancient and Honorable Artillery’s museum from water damage. Chuck Fazio, the museum’s lieutenant curator, says water leaked into the museum two years ago but did not destroy any artifacts.

Before the upgrade, the city did everything it could to maintain the old HVAC system short of “holding it together with bailing wire and chewing gum,” says Fazio.

Faneuil Hall reopened to the public in time for the tourism season on May 14. Crews continue to complete punch-list items. All work is on schedule to be done by July 12.

“I’m glad that the city bit the bullet and addressed the issue,” says Fazio. “Now this nightmare is finished.”