An introduction to pumping schemes in HVAC applications
In this module, you'll get a complete overview of chilled water pump applications in HVAC plants.
In this module, we will introduce you to the various types of chilled water pumping systems in HVAC applications.
While chillers are large contributors to the energy performance of a chilled water system, pump system configuration is also important to achieve optimal airconditioning plant performance. We're also going to take a look at the pumping schemes in air-conditioning applications as well as examine the various types of chilled water pumping schemes.
In short, a chilled water pumping scheme circulates chilled water throughout a commercial building or through cooling coils in air-handling, fan-coil and ceiling suspended units to provide space cooling.
In air-conditioning applications, the water pumping scheme is classified based on its use. One is used with chilled water pumps, designed for the distribution of chilled water to the conditioned space.
The other consists of condensor pumps designed to reject heat from chiller compressor coils to the atmosphere through cooling towers, connected through a network of pipes, valves and accessories.
Now, let's take a look at the various types of chilled water pumping schemes.
First of all, there's the constant primary circulation system. This is one of the initial schemes which was used in the Airconditioning industry for a very long time. But due to its inefficient energy performance, it is no longer used.
Next up, there's the constant primary and variable secondary circulation system, a system used in the airconditioning industry for decades. With the secondary pump being variable, this system offers a far more efficient solution than constant flow systems, since the secondary pump only uses the required energy to meet system demand. This essentially means that any unnecessary pumping is avoided. A system like this offers a number of benefits. It's easy to understand and implement, it offers a less complex setup, and it is far more efficient. On the other hand, it is occasionally prone to low Delta T issues which can reduce the installed chiller capacity in the plant.
Then, there's the variable primary flow circulation system. With its advanced control strategies of chillers and its energy impact on the overall plant performance, this scheme has become the norm for commercial buildings in the HVAC Industry. Furthermore, since it requires no secondary pumps and accessories, the initial investment is low. Combined with its highly efficient performance, you can see why this is a popular scheme within the industry. However, compared to other systems, the control setup can be slightly more complex.
Finally, there's Grundfos' Distributed Pumping system. With advanced pump controls and integrated sensors, Distributed Pumping optimises chilled water systems in commercial buildings by replacing centralised pumps and energy-consuming valves with intelligent pumps placed at each air-handling unit or combined with several fan-coil units or ceiling suspended units. Easy to install and commission, Distributed Pumping is an automatically balanced system, which is designed to always match the building's delta T and achieve optimal performance making it possible to save 54% on pumping energy costs.
That covers our module on chilled water pumping schemes.