Owner Case Studies
TekWorx Optimization Control Makes the Most of Condensing Boiler Plant Design of NYC High-Rise
Wet Well Retrofit Increases Efficiency and
Cuts Costs for Rockefeller Center
School District Boiler Retrofit
Boiler Plant Efficiency Improvement for Housing Complex
Award-Winning New Laboratory Project
Simple Boiler Operation for Apartment Building
Water Detection System Protects Datacenter
Rugged Snow-Melting Solution for Truck Ramp
Buddhist Temple Maintains Comfort with Floorwarming System
Equipment Protection Tracetek in NYCTA Rail Control Center
HVAC High Efficiency Plate Frame Heat Exchangers
The Pumps that Went to College
Progressive Thinking Leads to Dramatic Energy Efficiency for Suffolk County
TekWorx Optimization Control Makes the Most of Condensing Boiler Plant Design of NYC High-Rise
A TekWorx Control & Energy Optimization (CEO) System does the thinking for the unique heating and domestic hot water system designed for a building completed in 2005.
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Wet Well Retrofit Increases Efficiency and Cuts Costs for Rockefeller Center
The chief engineer at one of the buildings at Rockefeller Center in New York City had a problem: they were spending upwards of $21,000 annually for pit cleaning, odor control and enzyme treatment to soften solids of a sewage pit in addition to the cost of maintenance calls and overtime.
Rockefeller Center had a sewage pit at One Rockefeller Plaza with extremely heavy solids built up and laying on top of the water and grease built up on the walls. They were using vertical shaft sewage pumps as a duplex system with actuator style ball floats for level control and no real logic for controls. The pumps constantly failed from clogging and required a lot of attention. The check valves had been replaced several times due to rags caught on the flapper and the gate valves had failed due to wear.
GA Fleet provided a Duplex Flygt Submersible Sewage Pump system using model NP 3127 10 HP submersible pumps, each with a Flygt mix flush valve for suspending solids in the wet well. We provided state-of-the art, while simple to operate, controls with a unique Fleet control methodology for removing surface solids and preventing grease ring build up. All the functionality of a sewage pump station are built into the controller i.e. on, off, lead, lag, high alarm, low alarm and alternation. The levels are completely field-adjustable and there is no longer a need to enter the wet well.
To facilitate installation Fleet provided a unique FPS SubRig pipe and valve assembly. The SubRig is a pre-engineered, modular submersible pump piping system. Fully integrated with the frames and covers, and the electrical connection system, the SubRig facilitates easy, correct installation and uses components of better quality than the industry normally installs for this application. Engineers throughout NYC are now specifying SubRigs on new installations and many experienced plumbing contractors request them as well.
With the retrofit of the wet well the building has achieved a more efficient and far less tasking system than before, as well as saving on the life-cost of the equipment with minimal maintenance.
School District Boiler Retrofit
For this performance contract retrofit project, GA Fleet helped a Long Island, NY school district update 11 schools with 41 AERCO boilers.
AERCO boilers provide heat during 95% of the heating season. Peak load is augmented with cast-iron dual-fuel boilers. An energy management system controls boiler firing rate for maximum system efficiency. Hot water temperatures are reset from 180 to 100 degrees for maximum efficiency; hot water pumps operate on VFDs to vary flow in response to changes in building load. AERCO boilers operate properly without primary pumps, isolation valves, or other flow.
Project Update: 2006
Since the original contract work was completed in 1997, the school district has built a 200,000 sq ft middle school and a 350,000 sq ft high school. In both of these schools the newer, larger AERCO BMK-2.0 boilers were specified by the school district, and are used year round for both heat and domestic hot water.
Beyond the high efficiency provided by the AERCO boilers, the school district takes advantage of an Interruptible Gas rate, further reducing their fuel costs. In this case the alternate fuel is Propane-Air, an all-gas alternate fuel solution that allows the use of high efficiency gas-fired equipment, rather than lower efficiency oil-fired equipment. The propane air system consists of a buried propane tank, with a vaporizer mixer (shown) and fully automatic controls and safety features.
The propane air system was supplied by GA Fleet and is fully integrated into the district's EMS system.
Boiler Plant Efficiency Improvement for Housing Complex
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Boiler room shown before and after. |
This 50-acre Queens, NY housing complex called for the retrofit of 11 circa 1950 #6 oil-fired firetube boiler rooms with 60 high-efficiency gas fired boilers. Each boiler plant provides heat and domestic hot water to several garden apartment buildings. An energy cost study completed by the consulting engineer indicated a 250% improvement in overall boiler plant efficiency.
Award-Winning New Laboratory Project
This project in a newly constructed laboratory building uses a 2,000,000 BTUH boiler plant to provide low temperature heating water. Boiler controls communicate with Johnson Controls BMS to vary HW reset temperatures from 130 to 80 degrees for maximum efficiency. This project won the Governors Award for design.
Simple Boiler Operation for Apartment Building
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A 10,000,000 BTUH boiler plant provides heat and domestic hot water to this apartment building in the Financial District. The boiler room master control panel includes all boiler controls, pump starters and controls for simple operation by building personnel. Industrial grade components and design provide simplified operation, superior dependability, and easy maintenance of the complete boiler room mechanical system. This includes sequencing, power, and alarms for boilers, pumps, fans, motorized valves etc., all provided with easy to use H-O-A switches for positive control and simple operation.
Water Detection System Protects Datacenter
Real-world conditions, even in "clean" datacenters require rugged sensor cables, built from 100% non-corroding materials, and equipped with low profile connectors for ease of maintenance. Leak detection systems are often operating for years before a leak occurs. There is only one chance for early detection and location. After 20 years of development and improvements, the Patented Tracetek system is still the most accurate and reliable leak detecting and locating system.
This typical under raised floor sensor cable installation illustrates why only the most durable sensor cable (orange wire by stanchion running below datacom wiring) should be used. Conduits, copper grounding wires, and telecom wiring bundles cross over the sensor cables in many locations. The Tracetek sensor cable is insensitive to pressure and kinking, and can be provided with low profile connectors for ease of future removal for cleaning.
This example of the contamination present in a "clean" datacenter illustrates why only non-metallic, non-corroding materials must be utilized in the sensor cable. Only Tracetek uses conductive polymeric construction and insulation, exposing no metal to the environment to corrode.
Rugged Snow-Melting Solution for Truck Ramp
The most rugged, flexible, cut-to-length heater cables were selected for this industrial facility truck ramp. The ability to withstand vibration from commercial trucks, salt and other corrosive chemicals, and thermal expansion of the ramp assures heater cable life that will exceed that of the concrete ramp.
Cables are easily attached directly to rebar. A 2-stage pour is not required. Cable reels of 1000 feet each are provided and cut to length in the field. Field conditions often require modifications in cable lengths and layout from the original engineering design.
Heater cable power connections and terminations are above grade in accessible junction boxes. Only the rugged polyolefin jacket of the cable is in the slab. Rakes, shovels, and stone will not damage the heater cable. There are no buried splices that can fail due to poor manufacturing, handling, or galvanic corrosion.
Buddhist Temple Maintains Comfort with Floorwarming System
This Buddhist temple utilized over 11,000 feet of floorwarming cable to maintain carpet surface temperatures of 80 degrees for the comfort of its members. Finite element heat transfer models were generated by Raychem to design the floorwarming system with as little heater cable as possible. First floor heater cables were imbedded in the floor slab, second floor heater cables were located on the underside of the second floor slab.
Cables are installed prior to topping concrete pour. Cable reels of 1000 feet each are provided and cut to length in the field. Field conditions often require modifications in cable lengths and layout from engineering design.
Heater cable power connections and terminations are above grade in accessible junction boxes. Only the rugged polyolefin jacket of the cable is in the slab. There are no buried splices that can fail due to poor manufacturing, handling, or galvanic corrosion.
Custom made floor temperature sensing thermostats provide an additional level of control for comfort and energy savings. Capillary tubing of up to 50 foot lengths allow temperatures to be monitored in the center of the room(s). Installation in thermally conductive fluid-filled conduit provides rapid response and the ability for removal for future service.
Equipment Protection Tracetek in NYCTA Rail Control Center
The NYCTA's recently completed Rail Control Center, located in midtown Manhattan, is the central nervous system for the entire NYCTA rail system.
Miles of Raychem Tracetek water detection cables are located throughout the facilities raised floors. In the event of water leaks from piping, foundations, or other sources, the networked Tracetek alarm modules instantly report the presence of water, and the location, accurate to 1 foot, along the length of the cable.
HVAC High Efficiency Plate Frame Heat Exchangers
High efficiency plate frame heat exchangers are frequently utilized to isolate open from closed piping systems, and to provide pressure breaks in high-rise applications. Working pressures up to 400 PSIG are frequently required.
These three identical units are installed at 5 TIMES SQUARE in New York City. Provided with 10" reversing valves to insure high operating efficiency and reduce maintenance, the units have been in continuous operation since the building was put into service.
The Pumps that Went to College
This upgrade earns an A+ for eliminating clogs and saving energy.
By Jane Alexander
Set among 1,100 lush, wooded acres on the affluent north shore of Long Island, NY the campus of Stony Brook University bustles daily with approximately 20,000 students. Located 65 miles east of New York City, this SUNY College in the village of Stony Brook has grown tremendously during the 44 years since its founding. Students arrive each year from 50 states and 80 foreign countries.
The once quaint, idyllic college is now recognized as one of the nation's leading centers of learning and scholarship-fulfilling the mandate given by the New York State Board of Regents in 1960 to become a university that would "stand with the finest in the country." Identified as a Type I Research University by the Carnegie Foundation-the highest classification and a distinction granted to fewer than 2% of all colleges and universities nationwide-Stony Brook joins the ranks of such institutions as Harvard, Yale, Johns Hopkins, Princeton, and Stanford as the newest addition to the 63 members of the Association of American Universities (AAU). Stony Brook offers 119 undergraduate majors and minors, and 102 Masters, 40 Doctoral, and 31 Graduate Certificate programs.
Out of Sight, Out of Mind (But Not for Long)
Not surprisingly, as the university's academic reputation had grown, its enrollment had been swelling and its facilities multiplying at such a vigorous rate, that parts of the campus infrastructure had not kept pace. As often happens with both public and private institutions during periods of rapid growth, systems that are not visible can easily be overlooked or moved to a "deferred maintenance" list. In this case, one of the more notable systems to fall off the radar screen was the lift station that pumps the school's wastewater to its treatment plant. The results of this oversight were neither pretty, nor cheap!
As a matter of fact, the pumps in the Stony Brook Lift Station used to clog so frequently that crews for Suffolk County Department of Public Works (SCDPW) came to anticipate such an event as part of their weekly routine, recalls Ron Warren, Maintenance Director of the Division of Sanitation, Operations & Maintenance.
"The clogging became quite predictable," he says. "Every week to 10 days we'd have to go out there and free an impeller that had become jammed with rags or some other debris."
The problem-prone 3-MGD facility is just one of 87 pump stations and 24 wastewater treatment plants maintained by the Department. Built years ago, when the campus was smaller and generated less flow, the station and its original equipment simply couldn't keep up with the demands placed on it by the much larger university center and three outlying areas that comprise the Stony Brook of today. Although it would appear that the station's three, 60-HP pumps had ample capacity; the size of these units and their variable speed drives defininitely contributed to the clogging problem during low flow periods (which is most of the day).
Unfortunately, the problems that the SCDPW faced at the Stony Brook lift station are shared by many organizations that are responsible for similar stations equipped with large, variable speed pumps.
Searching for A Workable Solution
The Stony Brook station was designed with a 20,000-gallon wetwell and three 60-HP end-suction pumps mounted horizontally in the dry pit. Approximately two years ago, when the pumps were clogging as often as twice a week, SCDPW asked G.A. Fleet Associates, Inc., an engineering consulting group and manufacturer's rep, based in Harrison, NY, to recommend a workable solution that SCDPW's own engineering staff and crews could implement.
"Clogging is a problem we typically encounter when dealing with large, older pumps with variable speed drives," explains Mark Cavanagh, Service Sales Engineer with G.A. Fleet. "It was common practice in the past to oversize pumps, but that resulted in a unit running at minimum speed most of the day. Low-velocity flow contributes to rags and other material getting entangled on conventional impellers and eventually clogging the pumps. An oversized pump also demands a wasteful amount of energy."
After reviewing the original specifications and spending several months monitoring the station's flow, Fleet recommended replacing all three existing units with N-Pumps from ITT Flygt. This new type of pump has an innovative self-cleaning impeller incorporating a volute with a special relief groove that prevents rags, high-fibrous material, grease or solids from clogging the pump. The Fleet team based its recommendations on the results of tests at other installations where fouled impellers had been a recurring problem. During those tests, the N-pumps not only operated for extended periods without becoming clogged, they also achieved dramatic energy savings.
Figure 1. One of Stony Brook's three newly installed ITT Flygt N-Pumps.
G. A. Fleet further recommended changing the sizes of the three pumps to a combination of two, 60-HP Flygt Model NZ3300 pumps to handle peak flows (Figure 1), and a Base-Load pump to handle the low-flow conditions (See Sidebar). Instead of a third 60-HP unit, however, the Base-Load pump Fleet specified was a 20-HP Model NZ3152 model that would help reduce the station's energy consumption. Additional upgrades included a Flygt MultiTrode® Liquid Level Control System, a conductivity probe-based system that is fully compatible with SCDPW's new SCADA system, which operates on Citex software. According to Ron Warren, as a first step towards a full-blown, continuously monitored operation, SCDPW plans to add more MultiTrode systems and gradually network eight stations with SCADA.
Lessons Learned
One doesn't have to be a math major to calculate the return on investment for this successful project.
Today, over a year later, Stony Brook's Base-Load pumping system continues to run as designed-smoothly and efficiently. While G.A. Fleet Associates and the engineers and maintenance crews from SCDPW may not have been sitting in on any classes, they clearly earned an A+ for their teamwork on this particular college project!
For more information on the application and products referenced in this article, please contact: G.A. Fleet Associates 914-835-4000
Progressive Thinking Leads to Dramatic Energy Efficiency for Suffolk County
If a government can be both progressive and conservative, the leaders of Suffolk County, New York certainly qualify. It's progressive in that it passed Resolution #126-2006 requiring any county building project exceeding $1 million to incorporate green design principles. When that progressive thinking was put in practice during a renovation of the county's marine police bureau, the end result of significantly improved energy efficiency can't be considered anything but conservative. In fact, the energy savings have been so great since the installation of an AERCO Benchmark 2.0 (BMK2.0) boiler that the local utility called the county Department of Public Works (DPW), which supervises all of Suffolk County's engineering, to see if the facility's meter had been turned off.
Located on the south shore of Long Island where winters can be bitter, the Marine Police Bureau is a 15,000 square foot facility that houses the equipment and law enforcement professionals who keep the 1,000 miles of coastline safe for 1.4 million county residents. In order for vehicles to enter the facility for maintenance, a large bay door must be opened, thus allowing outside air to sweep through the main part of the bureau's first floor. Since most of the maintenance work is done during the winter, heating the facility was a challenge the existing system could no longer meet.
The 30-year old, oil-fired, hydronic modular boilers that fed unit heaters throughout the bureau were at the end of their useful lives. The six oil-fired units, which had a combined capacity of 1.2 million Btus/hr, now required frequent maintenance and repairs, further increasing operating costs and significantly impeding their ability to support the building's heating needs. For the County's Facility Engineering Division staff at the DPW, modest renovations to the Great River facility presented an opportunity to improve working conditions, as well as spend taxpayers' dollars more wisely.
Chief Engineer, Thomas LaGuardia, P.E., said, "This was the first major heating plant renovation to the facility in 30 years. I wanted to take the opportunity to upgrade the bureau with technology that would have long-term benefits, both environmentally and financially."
The County's other successful high-efficiency projects at other facilities served as a good reference, according to Principal Mechanical Engineer, Michael Monaghan, P.E. "We asked our Energy Engineer, Javed Ashraf, P.E., C.E.M., to consider a number of alternatives that might help to reduce operating costs significantly by just upgrading one component of the existing hydronic system - the boilers."
Ashraf contacted David Shepard, P.E., President of G.A. Fleet Associates, an AERCO manufacturer's rep, to learn more about the operating advantages of condensing boilers with very high turndown. At Ashraf's request, Shepard provided a list of local facilities designed with AERCO units. Among them was the Sachem School District, one of the largest school systems in New York State. Sachem had purchased 12 AERCO units from G.A. Fleet to accommodate several diverse load requirements, including space heating, domestic hot water and pool water heating, at its new high school.
"I conferred with Mike after a site visit to the school and several conversations with the school district's engineers and maintenance people. We knew that the AERCO technology was best for our needs, and Tom agreed," said Ashraf. "Then, it became a matter of which unit to select."
LaGuardia notes, "We chose the AERCO Benchmark because we felt the two-million Btu/hr heating capacity, coupled with its wide range in operating capability, would best fit the special needs of the Marine Bureau staff and building. The design challenges posed by the garage doors, the building's immediate proximity to the Great South Bay, and the operating profile of the Marine Unit's maintenance staff were all considered."
The BMK2.0 is designed to be operated in condensing mode for increased efficiency and delivers 20:1 turndown for a wide range of non-cycling operations. The unit matches any load between 100,000 BTU/hr. and its full two million BTU/hr. capacity without shutting down, minimizing cycling losses. Another benefit is that the boiler's efficiency -- up to 99% -- increases as the firing rate drops to meet the part load conditions which characterize the spring and autumn temperatures that greatly extend the heating season.
Suffolk County's additional challenge was to install the system in time to benefit from a utility incentive. Monaghan recalled the AERCO installation required a switch from fuel oil to natural gas and KeySpan Energy had offered the County an incentive if the conversion was completed by December 31, 2005. Here is where Ashraf's previous experience working for a utility helped, as did the hard work of Thermo Tech Combustion, Inc., the contractor hired for the project. Even though the project didn't begin until late November, it was completed before the deadline.
More than a year after installation, LaGuardia has proof that his decision to choose AERCO was a smart one. As shown in Figure 1, the county saved $11,780 in fuel costs in just the first year. Imagine his surprise when he received a phone call from the local utility. "Our savings were so great that KeySpan actually called to ask if we turned off the meter," he recalled.
For the Facilities Engineering Division staff at the Suffolk County Department of Public Works, the call affirmed their efforts and diligence - and was proof that government can be both progressive and conservative.
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