Grundfos has taken the lead on a distributed pumping application in HVAC systems.
This new method of distributing chilled water in buildings is an alternative to the conventional approach, designed to remove issues including Low delta-T, flow and temperature imbalance, and high commissioning costs which have plagued traditional distribution schemes.
Here, Ronak Monga, segment development manager (commercial building services) for the region at Grundfos explains the potential benefits of this new application which goes well beyond the conventional approach of managing and running HVAC systems, while also saving CAPEX and OPEX in new and existing buildings.
Chilled water systems with modulating valves are common air conditioning systems in today’s commercial and residential buildings.
However, these systems face challenges with balancing and poor dynamic flow regulation, which leads to severe energy loss, inadequate climate control, and an often uncomfortable environment.
All chilled water distribution systems require pumps for moving the chilled water, and all buildings have several terminal units such as AHUs, FAHUs, FCUs with different needs.
There are several reasons why chilled water loops can get out of balance, such as improper commissioning, components deteriorating over time, aging of the building, and changes to other parts of the system installation.
An imbalanced water loop can lead to a low Delta T, causing the chillers to work outside the best efficiency point and over pumping the loop.
This leads to excessive energy consumption and can result in an uncomfortable environment.
As a solution to these challenges, distributed pumping solutions are growing in popularity.
Replacing valves with pumps on each floor of the building, instead of centralizing them in the basement, provides continuous automatic balancing, reducing pump energy consumption and providing a more consistent and comfortable indoor climate.
Holistic solution to imbalanced water loops
Distributed pumping solutions are a paradigm shift away from centralised pumps in distribution networks towards decentralised pumps throughout the building.
By replacing balancing and motorised valves with pumps, the system is equipped only with components that generate pressure only when and where it is needed.
This reduces the time spent on balancing the system, as once the correctly sized pumps are selected, there are no valves needed to
balance the system.
Additionally, the main pumps can be downsized as distributed pumps generate the needed pressure individually, saving pump energy that way as well.
Distributed pumping solutions can be applied to existing chilled water systems that need refurbishment, or to new commercial buildings planned with chilled water air conditioning.
How distributed pumping works
Distributed pumping systems consist of five key components: primary pumps, distributed pumps, primary pump controller, check valves, and sensors located throughout the building.
The primary pump controller uses a control algorithm to manage the primary pumps, which are variable speed pumps that are regulated by sensor measurements from the decoupled line to avoid over or under pumping the system. Dedicated distributed pumps are installed with a non-return valve at each air handling unit (AHU) or a branch containing multiple FCUs.
The distributed pumps measure the air temperature using the AHU air duct sensor and will automatically regulate the speed to achieve the desired temperature.
Interfaces with the building management system (BMS), if installed, and other control options can be discussed during the design process, ensuring seamless integration based on the sequence of operations.
For multiples FCUs in the branch, the pumps’ in-built differential pressure control enables perfect proportional pressure control, so even the further FCU is adequately fed with flow and pressure to create perfect indoor climate.
A well-balanced loop system creates a well-balanced indoor climate
Distributed pumping solutions represent a new paradigm in chilled water air conditioning.
By providing consistent, accurate load balancing, distributed pumping solutions save energy and provide optimal comfort for people in the building.
They are also fast and easy to commission, reducing the initial investment and the time spent on system balancing.
For all these reasons and more, distributed pumping is becoming widely spread in commercial building projects around the world.