For a pump system to perform a low-flow shutdown, it must first be able to measure the flow demands in the system. Flow Switches and Flow Meters are mechanical means of measuring flow, which can work, but both require proper installation in the system piping for proper readings. Space and piping constraints can limit the installation of switches or flow meters.

Pressure Boosting System Design has also seen drastic changes in the same time period. Fifty years ago, large constant-speed, single-stage, centrifugal-pump systems were the design standard. These workhorses run 24/7, 365 days a year, regardless of the system demand in the building. This results in wasted energy and unnecessary wear on the pumps and piping. With smaller flow demands today, older pumps still in service are grossly oversized, making them much less energy-efficient.

More than 60 years ago, the late Dr. Roy B. Hunter developed a system for calculating water loads in commercial buildings. The estimated water demand of fixtures (water closets, sinks, etc.) is given a value called Fixture Units which have an equivalent demand load in Gallons Per Minute (GPM). The Fixture Units and Demand Load relationship is known as Hunter’s Curve and is still the basis for plumbing system design today.

Hunter’s Curve can be effectively used to calculate total system demand, but it has a glaring flaw. There is no consideration for diversity in the system demand. Using Hunter’s Curve for the basis of design of a Pressure Boosting System results in a pump system sized for all fixtures being used simultaneously, a scenario that will likely never happen. The pumps are grossly oversized for partial-demand conditions which make up 90% or more of total operation, causing poor system control and unnecessary wear on the pumps and piping system. In addition to Hunter’s Curve, Cougar USA uses field experience and data collection for system design.

To generate an accurate demand load profile, we gather as much information as possible about the building. The type of building has a huge impact on the load profile; even with similar fixture units, hospitals, hotels, schools, and office buildings will all have different load demands throughout the day and week. Special applications, the height of the building, locations of equipment, and potential future expansion are all factors in creating the right Building Load Profile. Once the system requirements are determined, we must make the right equipment selection.

In 2017, about 39% of total U.S. Energy Consumption was consumed by the residential and commercial sectors. In a commercial building, HVAC equipment (i.e., chillers, boilers, cooling towers, etc.) and lighting are the biggest targets for energy savings, but the capital costs for improving these may be prohibitive. There are many opportunities for energy savings and building performance improvements with other systems in commercial buildings.

Pumps are used in a variety of applications in commercial buildings, and 90% of them work inefficiently. There are three main reasons for pump inefficiency: pump type, size and controls. The proper combination of pump type, size and control will ensure the best system performance and lowest energy costs. Unfortunately, most pumps installed today are either improperly applied or sized and use outdated controls.

Domestic Water Pressure Boosting Pump Systems are required any time the city water pressure is too low to deliver water to a commercial building. Mid- to high-rise buildings almost always have pressure-boosting systems, and many single-story restaurants and medical facilities require high water pressure for special applications. In our experience, these systems usually suffer in all areas of inefficiency. Most are designed using fixture unit counts and maximum flow demands without looking at diversity factors and partial-usage loads. These calculations cause pumps to be oversized and incapable of performing well under partial-load conditions, which accounts for 90% or more of the total operation.