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Enhancing Sustainability Advantages of pressure independent control valves; basic commissioning of Belimo PI valves. © Belimo University 2011, All Rights Reserved. Enhancing Sustainability. First, an analogy between air systems and hydronic systems. .

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slide1

Enhancing Sustainability

Advantages of pressure independent control valves;

basic commissioning of Belimo PI valves.

© Belimo University 2011, All Rights Reserved

enhancing sustainability
Enhancing Sustainability

First, an analogy between air systems and hydronic systems.

Why are there no more VAV pressure dependent air systems?

enhancing sustainability3

Air Handling Unit

Supply

Duct

Return Duct

Bypass

Duct

Balancing Damper

VVT Boxes

Space

Temp

Enhancing Sustainability

Pressure Dependent VVT System

How many Pressure Dependent VVT systems have you seen lately?

enhancing sustainability4

Air Handling Unit

Supply

Duct

Return Duct

Bypass

Duct

Balancing Damper

VVT Boxes

Space

Temp

Enhancing Sustainability

Pressure Dependent VVT System

  • Part Load Performance:
  • Unable to respond to flow variation due to changing pressure conditions.
  • Unstable control – system is “oversized”.
  • Occupant comfort and energy efficiency are compromised.
  • Spaces too cold (or hot).
enhancing sustainability5

Controller

From Temp. Control

Water Flow Measurement Device

Water Flow

Enhancing Sustainability

Pressure Independent VAV Box

Air Flow

Temp. Control

Controller

Air Flow Measurement Device

  • Part Load Performance:
  • Flow is controlled under all pressure conditions.

Pressure Independent Control Valve

  • Stable control – system is “rightsized”.
  • Occupant comfort and energy efficiency are improved.
  • Spaces at or near design.
pressure independent control valve
Pressure Independent Control Valve

What is a pressure independent control valve?

A PI Control Valve….

Is a 2-way control valve that supplies a precise flow at any given control signal…

Regardless of pressure variations in a system.

It is not just a control valve and flow limiting circuit setter in the same assembly!

Note:

Automatic or manual balance valves should NOT be used with PI valves. If they are already installed they should be set WIDE OPEN.

pressure dependent control valve
Pressure Dependent Control Valve

Flow rate through equal % globe valve as a function of differential pressure (Cv = 1.9).

pressure independent control valve8
Pressure Independent Control Valve

Flow rate through PI Control Valve as a function of differential pressure (3 GPM valve plotted). Equal % characteristic.

equal valve characteristic
Equal % Valve Characteristic

100

90

Energy Characteristic of Coil

80

70

60

Coil Energy Output (%)

50

Flow Characteristic of Equal % Control Valve

40

Resulting Energy Output of Coil

30

20

10

10

20

50

90

0

40

60

80

100

30

70

Signal (%)

ASHRAE 2008 HVAC Systems and Equipment Handbook pg. 46.8

advantages

SAT Setpoint Change

PICCV Valve Water Flow

Advantages
  • Iowa Energy Center Pressure Independent Valves Study
    • Chilled Water Closed Loop Test

Globe Valve Water Flow

The Pressure Dependent Valve loses authority

at part load. In effect, it becomes “Oversized”

advantages11
Advantages

Energy saving potential

Globe Valve

PI Control Valve

advantages12
Advantages

Energy saving potential

Totalized Flow over 24 Hrs

Globe Valve = 358.7 gallons

PI Control Valve = 283.6 gallons

Note: The over-flow and under-flow cycling of this control valve results in a net over-flow condition!

advantages13

Globe Valve

PI Control Valve

Advantages

Energy saving potential

Pump Affinity Laws

HP = Horse Power

GPM = Flow in Gallons/Minute

Globe = 358.7 gallons

PI Control Valve = 283.6 gallons

A 26.5% increase in flow results in twice the horsepower requirements from the pump.

slide14

Pressure Differential Sensor

Setpoint = 10 psid

Pressure Dependent Control Valves

Design: 400 Ton / 800 GPM CHW System @ 12˚ΔT

Coil #40 - 200 gpm

10ft H2O (4 psid)

10 psid

4 psid

2 psid

Coil #30 - 200 gpm

10ft H2O (4 psid)

20 psid

4 psid

12 psid

Coil #2

0 - 200 gpm

10ft H2O (4 psid)

30 psid

4 psid

22 psid

Coil #10 - 200 gpm

10ft H2O (4 psid)

40 psid

4 psid

32 psid

Chiller

200 tons

VFD-Pump

Chiller

200 tons

VFD-Pump

advantages15
Advantages

Energy saving potential

For a given load, flow and ΔTare inversely proportionate.As flow increases, ΔT drops.

slide16

Pressure Differential Sensor

Pressure Dependent Control Valves

Design: 400 Ton CHW System @ 12˚ΔT

Coil #40 - 200 gpm

Coil #3 0 - 200 gpm

Coil #2

0 - 200 gpm

Coil #1 0 - 200 gpm

Chiller

200 tons

VFD-Pump

Chiller

200 tons

VFD-Pump

slide17

Advantages

Pressure Dependent Control Valves

180 Ton Load

(45%)

Design: 400 Ton CHW System @ 12˚ΔT

Coil #40 - 200 gpm

  • Hold the load constant and vary the flow.

Coil #3 0 - 200 gpm

Coil #2

0 - 200 gpm

Coil #1 0 - 200 gpm

(12˚ΔT)

54˚

42˚

CHWR

CHWS

360 GPM Loop Flow

slide18

Advantages

Design: 400 Ton CHW System @ 12˚ΔT

Pressure Dependent Control Valves

180 Ton Load

(45%)

Coil #40 - 200 gpm

Coil #3 0 - 200 gpm

Coil #2

0 - 200 gpm

Coil #1 0 - 200 gpm

(10.9˚ΔT)

52.9˚

42˚

CHWR

CHWS

396 GPM Loop Flow (+10%)

slide19

Advantages

Design: 400 Ton CHW System @ 12˚ΔT

Pressure Dependent Control Valves

180 Ton Load

(45%)

Coil #40 - 200 gpm

  • An increase in flow results in:
  • Lower return temperature.
  • Reduced ΔT.
  • Increased pumping power.

Coil #3 0 - 200 gpm

Coil #2

0 - 200 gpm

Coil #1 0 - 200 gpm

(10.4˚ΔT)

52.4˚

42˚

CHWR

CHWS

414 GPM Loop Flow (+15%)

slide20

Pressure Differential Sensor

Design: 400 Ton CHW System @ 12˚ΔT

Pressure Dependent Control Valves

Coil #40 - 200 gpm

Coil #3 0 - 200 gpm

Coil #2

0 - 200 gpm

Coil #1 0 - 200 gpm

With a 15% overflow

ΔT Reduction goes

From 12°F (Design)

To 10.4°F (Actual)

A reduction of 13%.

With a 10% overflow

ΔT Reduction goes

From 12°F (Design)

To 10.9°F (Actual)

A reduction of 9%.

Chiller

200 tons

Chiller

200 tons

slide21

Advantages

Pressure Dependent Control Valves

Design: 400 Ton CHW System @ 12˚ΔT

180 Ton Load

(45%)

360 GPM Loop Flow

CHWR

CHWS

(12˚ΔT)

54˚

42˚

Chiller

200 tons

VFD-Pump

90% Load

KW=1.0k

Arbitrary Value

Chiller

200 tons

VFD-Pump

  • Hold the load constant and vary the flow.
slide22

Advantages

Pressure Dependent Control Valves

180 Ton Load

(45%)

396 GPM Loop Flow (+10%)

CHWR

CHWS

(10.9˚ΔT)

52.9˚

42˚

Chiller

200 tons

VFD-Pump

90% Load

KW=1.33k

(396GPM/360GPM)3 = 1.33 (33% increase in pump power!)

Chiller

200 tons

VFD-Pump

  • An increase in flow results in:
  • Lower return temperature.
  • Reduced ΔT.
  • Increased pumping power.
slide23

Advantages

Pressure Dependent Control Valves

Design: 400 Ton CHW System @ 12˚ΔT

180 Ton Load

(45%)

414 GPM Loop Flow (+15%)

CHWR

CHWS

(10.4˚ΔT)

52.4˚

42˚

Chiller

200 tons

VFD-Pump

45% Load

An additional pump and chiller were started to meet the flow demand, not cooling demand!

KW=0.76k

(414GPM/360GPM)3 = 1.52 (52% increase in pump power!)

Chiller

200 tons

Chiller

200 tons

VFD-Pump

45% Load

KW=0.76k

Also, a chiller receiving cold return water can’t load up!

slide24

Belimo PI Valves

Two Solutions for Today’s Hydronic Systems

ePIV

2 ½” – 6”

105 GPM – 713 GPM

PICCV

½” – 2”

0.5 GPM – 100 GPM

slide25

Belimo Pressure Independent Valves

Commissioning

PICCV

(Equal %)

ePIV

(Equal % or Linear; factory or field selectable)

belimo pi valves
Belimo PI Valves

PICCV

Water passes through regulator Pressure is P2 (intermediate)

Water exits valve

Pressure is P3 (low)

Water enters valve

Pressure is P1 (high)

Ports sense pressure drop and transfer it below regulator

Low pressure pulls regulator down, against the spring force

slide28

Belimo ePIV

  • Smart Actuator
  • Magnetic Flow Sensor
  • Flow Feedback and
  • Control Signal
  • LGCCV Valve
slide29

Magnetic Flow Sensor

  • Measures changes to the induced voltage of a conductive fluid through a controlled magnetic field.
  • No moving parts or openings to clog or jam.
  • No maintenance.
slide30

Actuator/Flow Tolerances

Controller starts to control if delta "flow actual value" and "flow set value" > 5% (50% of the Flow tolerance)Controller stops to control if delta "flow actual value" and "flow set value" < 1% (10% of the Flow tolerance)

Flow Accuracy +/- 6% of Vnom

ExampleControl Signal Y = 100GPM (stable  no changes)

If the measured Flow is higher then 105GPM  Actuator will correct until measured Flow is 101GPM.

If the measured Flow is lower then 95GPM  Actuator will correct until measured Flow is 99GPM.

installation considerations
Installation Considerations
  • 5 straight pipe diameters before the flow sensor
  • no straight pipe requirement on the outlet of the valve
  • STRAIGHT INLET LENGTHS
  • 2-1/2” ePIV = 12.5” 4” ePIV = 20” 6” ePIV = 30”
  • 3” ePIV = 15” 5” ePIV = 25
installation considerations33
Installation Considerations

Actuator must be kept above horizontal!

introducing the epiv electronic pressure independent valve
Introducing – the ePIVelectronic Pressure Independent Valve
  • Cost effective flow sensor technology combined with Belimo’s industry leading intelligent actuators and proven characterized valve technology
  • Both non-spring and electronic fail-safe proportional models
  • Provides all the benefits of PI valves (accurate flow control, improved efficiency at part load by reduced pumping power, improved waterside ΔT)
  • Reduced cost, less weight, less raw materials, more sustainable!
  • True flow measurement, available to DDC system through feedback wire
  • Glycol concentration up 50% has no effect on flow measurement
  • Can be configured for either linear or equal percentage flow characteristic with a simple program change.
belimo field programming tool
Belimo Field Programming Tool
  • Field adjustable programming tool allows:
  • PICCV
    • Control/feedback signal
    • Custom flows/adjust flows
    • Many other parameter adjustments
  • ePIV
    • Control/feedback signal
    • Custom flows/bias adjustment
    • Flow coefficient
    • Equal % or linear setting
    • Many other parameter adjustments

ZTH-GEN

No external power needed; no battery; powered by actuator 24 vac! Just plug it into actuator.

belimo pc tool
Belimo PC Tool

ePIV adjustments (PC Tool v3.5 and above)

  • Control/Feedback Signal Voltage
    • 2-10 VDC
    • 0-10 VDC
    • User selected
  • Flow Characteristic*
    • Equal Percentage
    • Linear
  • Maximum (Design) Flow
  • Bias Adjustment
commissioning
Commissioning

Additional P/T PORT for verification of 5 psi (11.5 ft H20) minimum differential across the PI Valve.

Minimum ΔP across valve must be verified with PI valve COMMANDED by DDC (or by programming tool) to design flow, not manually positioned!

commissioning38
Commissioning

Step 1: Ensure all strainers are clean and bypass valves are closed.

Step 2: Command via DDC all PI valves to design flow. (Diversity assumed at 100%.)

Step 3: Set distribution pump(s) to elevated speed by commanding

ΔP setpoint or pump speed directly.

Step 4: Find the “critical zone” (ie. the PI valve that has the least ΔP).

Step 5: Increase or decrease pump speed/ΔP setpoint until critical

zone has just over 5 psid (11.5 ft H20). The resulting ΔP at the system sensor will be the optimum system ΔP setpoint.

Step 6: Verify total system flow is at design at main flow station (or by other method).

Step 7: If flow is not within +/- 10% of design, start checking valves at terminal level, starting with largest valve(s) first (voltage, control signal, strainer, etc.)

commissioning39
Commissioning
  • Belimo PI valves do NOT require that the entire system be placed in full design flow. Each PI valve flow can be verified individually with the rest of the system under normal control.
    • Command valve assembly to design.
    • Verify at least 5 psid across PI valve assembly.
    • Verify coil flow as per usual method (coil ΔP method, etc.)
  • Link for PI valve commissioning document:
  • www.piccv.com/pdf/PICCV_Application_Bulletin.pdf