In an ideal world, pressure sewer pumps would be sized and selected perfectly for their system and would last forever. Unfortunately, we do not live in an ideal world, and we often need to replace pumps. This may be because the pump has failed due to old age, system design, misapplication or the system has changed and the pump is now undersized. Whatever the reason, replacing a pump can be quite the undertaking, and it often needs to be done quickly, as the pump is critical to the sewer infrastructure. This is consistent across all different types and sizes, but one situation where pump replacement has been made easy is the residential grinder pump station through the use of the upgrade core.
Before getting into greater detail on what an upgrade core is, it is beneficial to explain where they are used. Typically, an upgrade core is designed to replace an existing grinder pump in a residential grinder station. These can be like-for-like replacements, where the upgrade core is replacing a failed pump of the same model. It can be replacing a pump that is now undersized with a more powerful pump or replacing a pump from a different manufacturer. The residential grinder station is typically part of a pressure sewer system, which uses residential grinder pumps to transport wastewater to a treatment plant or larger collection system through a network of small diameter pipes. Pressure sewers are typically used in places where a conventional gravity sewer is either cost prohibitive or not possible, such as hilly, rocky, flat or wet terrain. A typical installation includes a basin package containing a grinder pump, level control and an alarm box. This station is either buried in the homeowner’s yard or basement, and it services only that home. When that grinder pump fails, or the system changes, it is important to react quickly to keep the homeowner in service.
Now, what is an upgrade core? The core of a residential grinder station is the grinder pump and level control, as they are the key pieces of equipment. An upgrade core is just that—the grinder pump and level control, though it frequently upgrades the installation with more robust hydraulics, innovative pump features or a longer service life. What else is included varies based on the existing installation that the upgrade core is intended to replace. In some cases, there are structural items that hold the pump in place inside the basin, discharge piping and electrical connections that allow the core to be a drop-in replacement. In other cases, the core is fairly bare bones and requires a more custom installation. Upgrade cores can include a variety of different grinder pumps, meant to satisfy different system designs or installations, though they frequently have a flexible “one size fits all” pump curve due to the frequently fluctuating hydraulic conditions in a pressure sewer system. Upgrade cores can include centrifugal grinder pumps, multistage centrifugal pumps, progressive cavity and even turbine styles, among others.
The one common theme across these styles is a relatively low flow, high head performance curve. The core can also include a variety of level controls—different types of floats, pressure switches, transducers, etc. Upgrade cores can come without level controls as well. The configurations available in today’s marketplace mean there is an upgrade core out there for every installation. Some upgrade cores even come with electrical connections that match up to a different manufacturer’s power and sensor cords for rapid installation.
Upgrade cores are designed to be installed quickly and easily. Installation typically begins with closing the inflow valve, removing the old pump and disconnecting its power and/or sensor cord(s). After that, the upgrade core can be dropped into place. If there is an electrical quick connector, then the wiring is quick and easy. After opening the valve and testing the pump and level control test to ensure everything is working properly, the station is back in operation. This is beneficial, both to the installer and the homeowner, and it is convenient in emergencies. In the Southeast United States, upgrade cores are handy to have in inventory during hurricane season where massive flooding can cause large numbers of pumps to fail in a short amount of time. The quick change of an upgrade core means recovery efforts move quickly and people can get back to normal.
Another benefit of upgrade cores is being able to upgrade the pump performance with minimal cost and labor impact. Pressure sewer systems are typically designed to include long-term build-outs that can include thousands of pumps and stations in the final design, but sometimes those build-outs do not go to plan and the overall system ends up looking different than originally thought. Even if a build-out goes according to plan, it can often take years before the system is complete. When those changes happen or throughout the slow build-out, pumps can be undersized and underperforming, as a pressure sewer system must see a minimum velocity of 2 to 3 feet per second (ft/s) throughout the force main. Upgrade cores can be used to change the pump to a different hydraulic—one that provides more flow, more head, or whatever is needed so that the system is maximized to operate at its highest efficiency.
System changes do not always occur on the discharge side of the pump. They can change on the inflow as well. Whether it is a home that a new family moves into or a strip mall that suddenly gets a popular restaurant, the inflow can increase and decrease easily. This means a new pump may be required to keep up with the flow requirements, and an upgrade core is an easy way to make that change. An important note to make is that in pressure sewer systems, different grinder pump technologies can be mixed to optimize system performance. In one station, a progressive cavity grinder pump from one manufacturer can be installed. Meanwhile, a few streets over, a two-stage centrifugal grinder from a different manufacturer may be better suited.
While we do not live in a world where pumps are always the perfect size and last forever, technology like upgrade cores can make life easier when it comes to replacing or upgrading pumps.