Replacement of oversized boilers boosts warmth in public housing
The steel tube boilers were old, very old, had been in service since the 1960s, and were on their last legs. There were three in all, assigned with the task of providing heat and hot water to nearly 300 apartments at Dexter Manor, a 10-story low-income housing complex located in downtown Providence, RI.
One of the boilers was out of service and beyond repair, another had numerous problems and was completely unreliable, and the third, while still functioning, showed the telltale signs of old age. Thus, it was boiler replacement time at Dexter Manor.
The complex is owned and managed by the Providence Housing Authority, an agency heavily subsidized by HUD. When it comes to providing heat and hot water to its tenants, there cannot be disruptions to the service.
"Failure to provide our tenants with heat and hot water is simply not an option," said Gary Sprague, HVAC manager at PHA. "We have many elderly and handicapped people living in Dexter Manor who rely on our ability to provide heat and hot water. When it was apparent that we needed to replace the boilers, we had to develop an in-depth plan to install the new system without creating any problems or disruption in service for our tenants."
TYING INTO THE BASEBOARDThe PHA wanted new high-efficiency, gas-fired boilers that could be tied into the existing baseboard heating system in use throughout the build-ing. Besides providing heat and hot water, the PHA wanted a system that would be economical to operate in the long run.
Jeff Poliquin, project engineer for Creative Environment Corp., the East Providence-based mechanical engineering firm that designed the heating plant for the project, noted other challenges. "Besides the age and low efficiency of the existing three boilers, each of them was sized for six million Btu and extremely oversized for the building's actual needs," he said.
For the project, six RBI high-efficiency boilers were selected and installed. Two RBI Futera II hot water supply boilers accommodate the domestic hot water needs, and four RBI Futera III heating boilers provide building heat. The design called for four Futera III boilers each sized for 2 MMBtuh, with three operating on an ongoing basis and the fourth serving as a backup unit.
Johnston, RI-based Aero Mechanical was selected as the project's contractor. The firm's Kevin Pickett explained that a high efficiency rating of 88% and air/fuel mixing system were key components in the selection of the RBI units. "The system is also easy to service and offers a compact footprint to conserve valuable space," he added.
DON'T FORGET THE HOT WATERThe project consisted of three major elements: removing the existing three boilers and replacing them with gas-fired high -efficiency boilers; eliminating the heat exchangers providing domestic hot water; and isolating the heat from the hot water.
"One of the biggest challenges," said Pickett, "was that while we could stage the project for the warm weather months when heat was not needed, we still had to provide domestic hot water 24/7 throughout the building."
To do this, Aero Mechanical brought in a temporary boiler to supply hot water to the building. The temporary boiler resided in a trailer on the jobsite and tied into the existing 2,000-gal hot-water storage tank, which was ultimately replaced.
"The original storage tank failed inspection because the interior lining was collapsing," said Pickett. "So we installed two new 986-gal hot water storage tanks."
"To deal with the weather, we started the project in June, with the goal of making sure the heat was back on by October 1," said Pickett. "We actually completed the project early, and the heat was available to Dexter Manor residents by mid September."
Another issue was coordinating activities with all the other subcontractors on the project. This included electrical, sheet metal and fabrication, insulation, and asbestos abatement.
"At times, there were a dozen or more men working on the project at the same time, so it was critical that we had a good plan and lots of open communication," said Pickett.
"The level of coordination by all parties was impressive," said Peter Sweeney of Sweeney-Rogers, the New England representative for RBI. "Well before the project started, a series of meetings was held to ensure the synchronization of the boilers and jobsite requirements. Bringing the owner, mechanical engineer, mechanical contractor, and boiler rep together before the job starts is always the best way to ensure success."