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Keeping temperatures under control

PICVs combine cost savings and comfort

Pressure-independent combi valves (PICVs) play an important role in reducing

energy consumption while maintaining building temperature at optimal

setpoints. PICVs are effective because they use dynamic-balancing to handle

pressure fluctuations in a building’s hydronic system. Dynamic-balancing has two

major functions. First, it prevents the oversupply of consumers and the

subsequent hydronic interference. Second, it drastically reduces temperature

swings. As a result, the system uses less energy to maintain occupant comfort.

In addition, PICVs have a pre-setting function that provides even finer

temperature control accuracy, further eliminating temperature fluctuations and

discomfort. As a result, occupants are less likely to raise or lower temperature

settings, adding to the overall energy savings that the valves generate. PICVs also

allow for advanced pump control strategies that reduce energy use even more. In

total, PICVs can generate energy savings of up to 30%. They can be used in

almost any heating and cooling application to provide year-round comfort for

building occupants.

This paper discusses the energy savings methods in detail and includes a case

study example that quantifies them.

Saving Energy

using PICVs

How Dynamic-Balancing of

Hydronic Systems Yields up to

30% in Energy Distribution

Savings

siemens.com/acvatix

Summary of content (7 pages)

PAGE 1
Saving Energy using PICVs How Dynamic-Balancing of Hydronic Systems Yields up to 30% in Energy Distribution Savings Keeping temperatures under control PICVs combine cost savings and comfort Pressure-independent combi valves (PICVs) play an important role in reducing energy consumption while maintaining building temperature at optimal setpoints. PICVs are effective because they use dynamic-balancing to handle pressure fluctuations in a building’s hydronic system. Dynamic-balancing has two major functions.
PAGE 2
White paper | Saving Energy using PICVs | June 2017 PICVs in the Hydronic Context Dynamic-Balancing Against Pressure Differences Enabling Energy Savings in Three Different Ways Pressure-independent combi valves (PICVs) ensure that the flow of hot or cold water is solely dependent on valve travel. Within their range of operation, they are not affected by pressure fluctuations in the building’s hydronic system. This is called dynamic-balancing or auto-balancing.
PAGE 3
White paper | Saving Energy using PICVs | June 2017 Avoiding Overflow Different Resistance Leads to Under- or Oversupply In hydronic heating and cooling systems, the hot or cold medium distributing the thermal energy from its generation to the consumer (water, either plain or mixed with an agent like glycol) is transported over piping sections of different lengths and diameters. In the case of multi-story buildings, the elevation to overcome may also vary.
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White paper | Saving Energy using PICVs | June 2017 Improving Control Accuracy PICVs Eliminate Overflows with Dynamic-Balancing Users Shift the Setpoint to Reduce Discomfort As stated in the description of the PICV working principle, the use of PICVs limits the maximum flow at part-load conditions and thus avoids the mentioned increase of direct energy demand (generation, consumption) and indirect energy demand (transport, distribution).
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White paper | Saving Energy using PICVs | June 2017 Full-Stroke Further Increases Control Accuracy Even finer control accuracy is provided by Siemens PICVs, in which pre-setting is obtained by limiting the free control path area. Since the full travel of the flow control valve is available to manage the opening, the volumetric flow can be defined using a much larger number of steps (Figure 6).
PAGE 6
White paper | Saving Energy using PICVs | June 2017 As PICVs Maintain Flow, Pumps Optimize Pressure On the other hand, PICVs make it possible to deliver the same flow at a lower pressure difference. As long as the pressure difference remains in the allowed PICV operating range, the flow will be maintained at the set level (autobalancing feature).
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White paper | Saving Energy using PICVs | June 2017 Published by Siemens Switzerland Ltd 2017 Building Technologies Division International Headquarters Gubelstrasse 22 6301 Zug Switzerland Tel +41 41 724 24 24 © Siemens Switzerland Ltd, 2017 7