A Grundfos integrated pressure-boosting system makes the difference for several Seattle buildings.
Faced with a failing domestic-water booster pump at one of the downtown commercial properties managed by Martin Selig Real Estate, Seattle, chief engineer Phil Boyd began searching for options to repair the existing tri-plex boosting-pump system.
The booster station serves the 43-story commercial office building at 1000 2nd Ave., located blocks from the Puget Sound waterway. Such high-rise buildings—including hotels, multifamily, office, and other institutional applications—require pressure-boosting equipment to raise incoming municipal water pressure to serve upper floors. Demand for water in such multi-story buildings can vary significantly throughout the day, and this unpredictable flow places extraordinary demands on pumping equipment.
Boyd planned to repair the pumping station until Corey Rasmussen, sales manager for Grundfos Pumps Corp., Downers Grove, IL, suggested that the property- management’s investment would be better spent on a new, more efficient water-boosting system. To support this recommendation, Rasmussen advocated an independent energy audit to determine the building’s actual pressure requirements, given the condition of the existing 27-yr.-old pumps.
“We had absolutely no doubt that we could significantly lower the operating costs of the existing unit by using intelligent, demand-based pump technology,” recalled Rasmussen, who nonetheless provided Boyd the $17,000 repair quote. “The problem, however, was convincing a price-conscious customer to invest in new technology instead of rebuilding the decades-old pressure-boosting pumps and motor drives.”
Unknown to Boyd, Rasmussen already had a solution in mind. His trump card was the Grundfos Hydro MPC BoosterpaQ, an integrated pressure-boosting system that would deliver the exact water pressure necessary to achieve optimal performance—all without direct human intervention.
Ideal for water-supply systems, as well as municipal boosting, water transfer, and industrial applications, these integrated pumping systems use an advanced controller to adjust pump speed and stage additional pumps as necessary to meet specific pressure demand.
“Initially, Martin Selig was looking at the possibility of rebuilding the existing pump station. After looking into the costs, we realized it made better sense financially to upgrade to a more energy-efficient system,” said Boyd.
Anxious to demonstrate the value of replacing rather than repairing the pressure-boosting system, Rasmussen contacted Grundfos colleague Roger Weldon, CEM, LEED AP, energy-optimization engineer, to arrange a pump audit. Weldon had extensive experience with this type of application and traveled to the site to install the pump-audit equipment (flow, power, pressure meter/loggers) onto the existing pressure-boosting system. The pump-audit equipment recorded performance data for two weeks.
According to Weldon, “The data derived from the pump audit allows us to select the optimum replacement system that is often substantially smaller and less costly to purchase and operate. Additionally, the data we collect is used to apply for utility incentives, which help to boost the company’s return on this capital investment.”
The existing system
The pumping station currently used a pressure-boosting system that was installed when the building was constructed in 1987.
“The building’s existing pressure-boosting system, which consisted of one 20-hp and two 30-hp vertical turbine pumps, ran at full speed and the pressure was controlled by pressure-regulating valves that significantly reduced the system’s overall efficiency, and would require scheduled annual maintenance,” said Boyd.
Due to the simplistic control technology, one of the pumps ran 24 hr./day regardless of flow demands, which are significantly lower during overnight and weekend periods when the building is unoccupied. The current control scheme not only wasted electricity but also decreased the equipment’s life expectancy as a result of the excessive heat and hydraulic forces generated from operating when there is no flow demand.
One way to leverage the savings realized by moving from a constant-speed pumping system to a variable-speed, demand-based platform was to apply for a utility incentive. Weldon worked with the local utility, Seattle City Light, a publicly owned electric-power utility, to secure a large power-reduction incentive for the property-management customer. Like many utilities, Seattle City Light’s Energy Smart Services program, offered financial incentives to help medium and large businesses reduce electricity use, save money, and shorten the payback on energy-efficient investments.
“After the new Hydro MPC BoosterpaQ was installed, the utility’s technical metering team monitored the power consumption of the pressure-boosting equipment over a two-week period starting at the end of August 2014 to account for changes in load demand, and compared this data against the estimated power consumption of the new unit,” explained Lisa Frasene, energy management analyst, Seattle City Light.
Noted Frasene, “Incentives are based on total annual kilowatt hour (kWh) savings over the first year of the project. Combined rebates from all utilities may not exceed 70% of project costs and the incentive amount is capped to a minimum payback period of six months.” Seattle City Light is currently offering an incentive rate of $0.27/kWh reduction in the first year of operation for this type of project.
“With an annual estimated energy savings of 108,624 kWh, or $7,604, the high-efficiency pressure-boosting system would qualify for a one-time incentive payment in the amount of $29,328,” continued Frasene. “Simple payback is estimated to be 5.1 years, and each year thereafter, the business will save an estimated $7,600 in reduced electric bills.”
The financial returns on the project were outstanding, as is often the case in the Seattle/Tacoma/Bellevue area due to the generous incentives being offered by the utilities, explained Weldon.
“The energy savings from the Grundfos pumps were impressive,” said Boyd. “The new ‘right-sized’ water booster system has a lower initial cost than a ‘like-sized’ system, costs less to operate, and the utility incentive would pay for nearly half of the system.”
Matching Output with Demand
The replacement Hydro MPC BoosterpaQ system is a state-of-the-art pressure-boosting system. The unit is equipped with efficient and reliable Grundfos CR vertical multi-stage centrifugal pumps. Each of the pumps is coupled to a 7 1/2-hp Grundfos MLE integrated variable-speed drive and motor.
The Multi-Pump Controller (MPC) manages VFD controlled pumps in parallel fashion. The pump performance curves are loaded into the controller on the Hydro MPC BoosterpaQ, which selects the most efficient combination of pumps and pump speeds to precisely match the flow and pressure demand.
“In recent years, variable-frequency-drive technology has become more affordable and critical in bringing intelligent speed control to a number of commercial pumping applications, including domestic water boosting,” explained Rasmussen. “The ability to adjust the pumping system output based on system demand was the primary reason we knew we could significantly reduce energy consumption for this building.”
“The replacement BoosterpaQ system has performed very well; it is very quiet and maintenance-free,” said Boyd. “We are saving money in maintenance and energy costs.”
Success Leads to Similar Upgrades
Due to the success of the booster-pump retrofit at the 1000 2nd Avenue location, Boyd got the green light to make similar upgrades at two more downtown office buildings.
By replacing the pressure-boosting system in these three commercial properties, Martin Selig Real Estate management has:
- lowered the power consumption in each building
- improved the reliability of the pressure-boosting systems and almost eliminated the annual maintenance costs associated with each system
- avoided costly repairs of obsolete systems
- increased property values.
Grundfos was able to provide a total turnkey solution, which means they only had one vendor to deal with, making life simpler and easier for their staff. “Martin Selig did not even consider purchasing another pumping system because the Grundfos team demonstrated its ability to take a project from evaluation to installation,” concluded Boyd.