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Volume XXIX, Number 6108
Monday, Jun 02, 2014

Arsenal Energy Efficiency Improvements Part 1: Heating

Maintenance worker Andrey Chekalov replaces a steam trap and corrects the pitch of a radiator in the Arsenal;
Maintenance worker Andrey Chekalov replaces a steam trap and corrects the pitch of a radiator in the Arsenal;
Photo by Matt Brown

The Arsenal just became more energy efficient thanks to a refurbishment of the building's heating system and two lighting retrofits, spearheaded by the Parks Energy and Sustainability Team. Today and tomorrow, The Daily Plant presents a two-part series on these projects. Read below for today's article about the heating system refurbishment, and stay tuned for tomorrow's article on the lighting retrofits.

The Arsenal is of particular interest to the Energy and Sustainability Team because the building is Parks' largest energy user, not to mention the agency's headquarters. With the Arsenal's high profile and high energy use in mind, the team invited renowned steam heating expert, Dan Holohan, to tour the building after he led a heating training for 44 Parks employees on January 9. On the tour, Holohan identified several opportunities to improve the operations and efficiency of the building's heating system. Following Holohan's recommendations, Parks engaged in a three-month refurbishment of the system.

Lacking a boiler, the Arsenal is heated by Con Edison steam, which is purchased by Parks and provided through a large pipe in the steam vault under the sidewalk. From there, the steam travels through vertical pipes called risers, and then through distribution pipes into radiators throughout the building. At radiators, the steam loses its heat, warming surrounding areas, and condenses back into water, or condensate. The condensate returns to the basement in its own set of pipes called condensate return lines and exits the building into the city's sewer system. Of critical importance in the system are devices called steam traps that are fixed to the bases of radiators and risers to prevent steam from entering the condensate return lines, while allowing condensate to pass through.

The principal issue with the Arsenal's heating system was failed steam traps throughout the building, as well as clogged condensate return pipes. Steam traps have internal moving parts that must be replaced every three to five years, and many traps in the Arsenal were well past that life expectancy. As a result of these conditions, parts of the Arsenal received too much heat, while others did not receive enough heat. "It's pretty simple: if air and water can't get out of the system, steam can't get in," Parks' Energy Manager, Matt Brown described. "And if steam can't get in, the heat doesn't work." In order to comprehensively solve these problems, the Citywide Services Boiler Team and Manhattan Shops - under the direction of the Energy and Sustainability Team - worked in collaboration to replace steam traps and piping throughout the building, while adding numerous air vents to one critical section of the system. These changes now allow air and condensate to more effectively leave the system, improving heating distribution, while using less steam.

In addition to these infrastructure issues, the Arsenal steam system had one other substantial challenge: the system lacked independent heating controls for different parts of the building, so the system either had to be completely turned on or completely turned off. To better regulate heat, the Boiler Team installed Danfoss thermostatic radiator valves (TRVs) on every single radiator in the building. Each TRV has a dial that allows the room's occupants to set the desired heating level, thereby regulating steam flow. Because the Arsenal's heating system was usually turned on throughout the winter, this added level of heating control should ultimately reduce total energy use. To learn more about the TRVs, look for the new informational flyers in the Arsenal.

The Boiler Team and Manhattan Shops finished this steam heating system refurbishment in mid-May, after starting the project in mid-February. In order to minimize disruptions to the Arsenal Staff, they conducted most of the work on weekends. While the heating season for 2014 ended on May 15th, Parks can expect benefits from the project for years to come.

Currently, the Energy and Sustainability Team is gathering data to measure the impacts of this steam system overhaul. One initial measure of success is the amount of time it takes for the building to heat up. "Before this work, when starting the system back up from being turned off, it would take 90 minutes for the system to get hot," Brown recalls. "Now, the farthest radiator gets warm in about five minutes. Trades people involved in the project said it's now the best-functioning steam heating system they've ever seen.” The Energy and Sustainability Team plans to build on the successful project in the Arsenal, repeating this repair process in all of Parks' 50 largest energy-using facilities.

Want to learn more about heating systems? Check out Dan Holohan's website at

The Energy and Sustainability Team is engaged in other similar energy saving projects, from installing pool covers at indoor pools, to overhauling lighting systems in recreation centers. For more information on these efforts, visit the new Parks' sustainability intranet page at http://wss.parks.nycnet/Sustainability/default.aspx.

And stay tuned for tomorrow's article on the lighting retrofits in the Arsenal.

Submitted by Nicholas E. Cohen, Sustainability Analyst


"All things are difficult before they are easy."

Dr. Thomas Fuller

(1654 - 1734)

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