How distributed pumping works in a single room
In this module, we will show you the benefits of distributed pumping in commercial buildings based on two simulations –– one focusing on four equally sized fan coil units in a single room, the other focusing on buildings with multiple fan coil units.
For years we have installed fan coil units using control valves and balancing valves to throttle the flow from a central pump. But today, there is a new way of doing it: distributed pumping.
In distributed pumping, the balancing valves on the fan coils are replaced by a single variable speed pump, and at each air handling unit both the control valve and balancing valve are replaced by a variable speed pump.
In this module, we’re going to introduce you to the benefits of distributed pumping and show you two simulations…One focusing on four equally sized fan coil units in a single room, the other focusing on buildings with multiple fan coil units. Distributed pumping is a much-improved solution that offers several benefits. In short, these include:
• faster commissioning
• reduced energy consumption
• less maintenance
• and increased comfort.
Now, let’s take a look at the first of our two simulations which has four equally sized fan coil units in a single room with an initial temperature of 28°C. Let's take a look at how efficiently that distributed pumping can cool the room to a temperature of, say, 22°C.
Now, let's replay the footage. This time, we’ll focus on the temperature curves instead.
As you can see, reaching the desired temperature of 22°C only takes a few minutes.
Let's see it one more time and look at the power consumption of the pump. As the pump only provides the necessary flow, power is saved.
Finally, let’s check out the flow curves where 100% equals the design flow. Occasionally, some coils may exceed the design flow by more than 50 %. However, that is not a problem, and as we saw before, the system was able to reach the set temperature in a very short time.
Now, let’s change our focus and look at our next simulation. This time, we’ll focus on a building with multiple fan coil units. Let’s ask ourselves this: Is Distributed pumping beneficial in a building with many fan coil units? Or would it be too expensive? The answers are simple – yes, it is beneficial, and, no, it is not too expensive. One pump can easily serve multiple units, without sacrificing the many benefits of distributed pumping. So, how many units exactly can be supplied by one pump?
That depends on the length of the pipes between them. To illustrate this, we have simulated a situation where the distance of pipe between each fan coil unit is the same.
On this chart, the Y-axis highlights the opening of the control valve, and the X-axis shows the number of fan coil units. If there’s a 1-metre pipe between the fan coil units, we can add up to ten units before we reach 100%, after which control is no longer possible. With a 3-metre pipe, it is 7 units. And at 5 metres, there can be 6 units on the same string.
So as you see, distributed pumping allows you to have multiple fan coil units on the same string without the use of hydronic balancing. If you need even more fan coil units, you can manage that by adding balancing valves to the specific string.
So now you've seen two demonstrations of how to use distributed pumping. Let's sum up the main benefits of this offering.
With distributed pumping you can achieve:
• Faster commissioning,
• Significant energy savings
• Less maintenance
• and increased comfort.
That covers our module on distributed pumping.