This document provides an agenda for a class on hydronic system design fundamentals. The agenda includes: 1. A short introductory class on very basic hydronic system concepts and taking notes. 2. A general class covering: - Design problem analysis - System design and calculations - Pump selection - Control and system balancing - Advanced concepts 3. Review of key hydronic system design concepts like Bernoulli's equation, pressure units, and air management in hydronic systems. 4. Overview of the closed loop hydronic system design method including calculating facility load, selecting heat transfer devices, calculating system flows, schematically designing piping, and addressing piping configurations.

1. Agenda
1. “Short Class”
Fundamentals of Hydronic System Design
1. Very Fundamental
2. You take notes
May 8, 2009
ASHRAE Region 6 2. General Class Flow
Chapters Region Conference
1. Design Problem
Mark Hegberg
2. System Design & Calculation
Product Manager, Danfoss Heating Controls
3. Pump selection
4. Control & System Balance
5. Advanced Concepts
Daniel Bernoulli Bernoulli Equation
V12 P1 V2 P P2
z1    z 2  2  2  HL V2
2g ρ1 2g ρ2
HL Z2
P1
V1
Z1
1

2. Bernoulli’s Equation... Pressure Units
• Elevation - Potential Energy Of The System, Lifting The
Fluid
Standard 14.7 PSIA
• Fluid Velocity: Kinetic Energy and Effects of Gravity or
Atmospheric
• Pressure & Density: Flow Energy Work Done On Pressure 0 PSIG
Surroundings By Fluid
Z  Elevation
V2
 Fluid Velocity In Pipe
2g Perfect 0 PSIA
P  Pressure or
Vacuum -? PSIG
ρ  Fluid Density
HL  Head Loss
Hair Gear
Spring
Units: Pointer
• Inches
Difference • Feet Link
In Length • Millimeters Bourdon
• Meters Tube
Sector
Liquid Fill & Pinion
• Water
• Oil Stationary
• Mercury Socket
Pressure
Connection
2

3. Pressure
• Or Another Way Of Looking At It;
1'
1' 62.34 Lb. 1Ft 2

Ft 3 144 In2
Water
1' 62.34 Lb
Lb.
0.443
12" In2 or 2.31Ft
Or: 0.433 psi / Ft. 12" Ft 1PSI
• A 231 Foot Long Manometer Is Inconvenient for Measuring
100 PSI, and In The Old Days A Common Dense Fluid Was
Mercury...
1' Standard 14.7 PSIA
Atmospheric or
1' 844.87 Lb. 1Ft 2 0 PSIG
 Pressure
Ft 3 144 In2
Mercury
1' 844.87 Lb Lb. ≈30 In Hg
5.87
In2 or 0.17 Ft
12" Ft 1PSI 0 PSIA
Perfect
or or
12" Vacuum -? PSIG
2.04 In Hg
1PSI
3

4. Standard
Atmospheric
Pressure
Standard 14.7 PSIA
Atmospheric or  Lb Lb  In Hg 1
0 PSIG 14.7 2  11 2   2.04  7 In Hg
Pressure  in in  PSI 2
≈30 In Hg
11 PSIA
Perfect 0 PSIA Perfect
or
Vacuum -? PSIG Vacuum
Pressure Static Pressure
• For this class our reference will be;
• Static Pressure Is The Elevation
• It’s Created By The Weight Of A Vertical
Column Of Water
4

5. And That Other Unit of Measure? Feet of Head
Feet of Head Why Use Pump Head?
Pump Rated For 30 Ft Head @ Flow
Density = 62.34 lbs/cu ft Density = 60.13 lbs/cu ft Density = 57.31 lbs/cu ft
• Remember Bernoulli Really Described Energy 62.34  144 = 0.43 psi/ft
2.3 ft / psi
60.13  144 = 0.41 psi/ft
2.44 ft / psi
57.31  144 = 0.40 psi/ft
2.5 ft / psi
• Pumps Do "Work" On The Water 30 ft X .43psi/ft =12.9psi 30 ft X .41psi/ft =12.3psi 30 ft X .40psi/ft =12.0psi
12.9 psi X 2.3 ft/psi = 30 ft 12.3 psi X 2.44 ft/psi = 30 ft 12.0 psi X 2.5 ft/psi = 30 ft
• Work Is Measured In Ft-Lbs
• Water Is Measured In Pounds 92.9 psi 92.3 psi 92.0 psi
Ft - Lb P=12.9 P=12.3 P=12.0
Lb 80.0 psi 80.0 psi 80.0 psi
Water @ 60 F Water @ 200 F Water @ 300 F
5

6. Review Design Problem
• Pumps Do The Work: They Add Energy To the Fluid
System • Three Story Building
– We “Pump” Pounds of Fluid – Four Zones Per Floor
– Work Measured In Foot-Pounds – Each Zone 14 Tons Air Conditioning
– Foot-Pounds of Work Per Pound Fluid Pumped – 168 Total Tons
• Pounds Cancel; We’re Left With Feet or “Head”
– Evaluate at Constant Entering Air 78½°F DB,
• “Density Independent”
65½°F WB
• Three Components To Total Head (Work)
– 42°F EWT, 16 ½°F ΔT
– Elevation, Velocity, Pressure
• Work Done on System Components
– Head or Pressure Losses
Develop “Flat” Layout
6

7. Closed Loop Hydronic System Design Method
Air Management How Does It Work?
• Air Is In Water, and Goes 1. Calculate Facility Load
Into and Comes Out Of • Pumps Provide
Solution As A Function Of  Set Space Design Criteria
Differential Pressure By
Pressure & Temperature Converting Electrical  Building Code Requirements
Energy To Move Water  ASHRAE Requirements
 Standard 62.2; Air/Ventilation Requirements
 Standard 90.1; Energy
Pump
 Standard 55; Thermal Comfort
Coil
 Standard 111; Test & Balance
• Adds Heat  Guideline 1; Commissioning
• Rejects Heat
 Examine Load Requirements
• Changes Water
Temperature Source  Zone Distribution
• BTU/Hour Pipes  HVAC Method
• Pipes & Coils Provide “Resistance” You Use  Diversity; Do Not Use Diversity When Sizing
Pipes & Pumps
Energy In Form of Pressure To Move Water
System Load System Impacts
• •ASHRAE’s Latest: 1998 “Cooling &&
ASHRAE’s Latest: 1998 “Cooling
Heating Load Calculation • Heat Transfer Becomes Water Flow
Heating Load Calculation
Principles” (RP-875) Pedersen,
Principles” (RP-875) Pedersen, – Over Estimation Causes Over Calculation of Flow
Fisher, Spitler, Liesen
Fisher, Spitler, Liesen
• •Air Conditioning Contractors of – Energy Efficiency Impacted
Air Conditioning Contractors of
America
America – Leads To Bigger Coils & Oversized Control Valves
• •Manufacturer Load Programs
Manufacturer Load Programs • Controllability Impacted
– System Load
– System Load
– Block Load
• Changes Desired Coil Performance
– Block Load
• •“Old” Carrier Manual “Engineering
“Old” Carrier Manual “Engineering
Guide for System Design” (1963)
Guide for System Design” (1963)
7

8. Closed Loop Hydronic System Design Method
Calculate Flow
2. Select Heat Transfer Devices
 Source; Desired System Operating Differential • Flow
Temperature
 Load; Coil that offers required performance at
calculated gain conditions
 Heating, Cooling & De-Humidification
 Operating system differential temperature Q  m  cP  ΔT
3. Calculate and “Analyze” System Flows lb. min Btu
Q  8.34  60  GPM  1  (TLvg  TEnt )
 Total System Flow gal hr lbm  F
 Zone Flow
Q  500  Flow  T
 Can the required operating differential temperature
be achieved?
 Alternative piping and pumping considerations
Required Water Flow Thank You! Scott Blackmore & B&G
System Syzer
Q  500  q  ! T
(14  12,000)  500  q  16.5
(14  12,000) • Scale 1
q  20 gpm • Align 16½°F ΔT
500  16.5
• 168(,000)
• 80 GPM / Floor • Read Flow
• 240 GPM Building
8

9. 240 160 80 Hydronic Coil Heat Transfer
40 40 40
80 80 80
20 20 20 20 20 20
40 40 40 40 40 40
• Air Side Heat Transfer • Water Side Heat
Transfer
20 20 20 20 20 20
q  UA( LMTD ) q=mcp(t2-t1)
80 80 80
40 40 40 Where LMTD is the air-
water log mean Where t is the water
temperature difference temperature rise
240 160 80
2 Pipe Control Hot 120%
Water Hot Water Coil Heat Transfer
Hot Water Coil Heat Transfer
Performance Vs. Water Side ΔT
Performance Vs. Water Side ΔT
Coil
M C 97.5% 100%
The coil
Heat The coil
performance
Transfer performance
is not linear
is not linear
% Heat Transfer
80%
T
°Δ
T
20
T
°Δ
t1
60
60%
Al
t2
Al
40%
20%
75% 90%
Design Design
0%
Flow Flow
% Water Flow
9

10. Coil Heat Transfer General Coil Notes
100%
4 Row Tot Total Heat Transfer
90%
4 Row Sens
4 Row Lat • Traditionally, sensible heat transfer is
80%
5 Row Tot
5 Row Sens controlled by throttling flow
5 Row Lat 100%
• Coil performance tends to be non-linear
Percentage Heat Transfer
6 Row Tot
70%
6 Row Sens
6 Row Lat
Sensible Heat Transfer
60% – More non linear with low water ΔT (6ºF)
50% – More linear with higher water ΔT (16ºF)
40%
50% • Coil pressure drop affects
30%
– Main & branch pipe sizing
100%
20%
– Control valve operation (valve authority)
10% 50%
– System balance
Latent Heat Transfer
0% 0%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percentage Water Flow Rate
4. Schematically Design Piping General Notes: Air Bind
 Select Terminals / Heat Transfer Coils
 Component Drops • Adequate Operating Differential To Create Flow
 Note Coil Characteristic for Temperature Drop
 Locate Terminals / Heat Transfer Coils
 Address Area Fit Constraints 1½’
– Size of Unit 3’ Air
– Area of Application Water
 Examine Piping Geography A B
 Develop Pipe Sizing Criteria
 Select Control Valve Supply Main Return Main
 Examine Valve Authority
10

11. General Notes: Air Bind General Notes: Air Bind
• Adequate Operating Differential To Create Flow
1½’
3’ Air 3’
Water Riser Water Level
1’ Displaced By 1’
B Supply Main Return Main B B Supply Main Return Main B
ΔH A to B = 1’ ΔH A to B = 5’
General Notes: Air Bind Ensure Adequate Differential
Potential For
Air Binding
Low Pressure Drop Low Pressure Drop
High
Pressure
Drop
3’
Supply Main
A
B Supply Main Return Main B ΔH
ΔH A to B = 5’
B Return Main
11

12. Avoid Ghost Flow Circuits Piping Configuration
• Single Pipe Systems
– Single Load
– Multiple Load
Open
• Two Pipe Systems (Supply & Return)
A
– Constant Flow Single & Multiple Load
– Variable Flow Single & Multiple Load
Closed
B • Hybrid Systems
– Bypass Systems
– Primary-Secondary-Tertiary
Single Pipe System Single Pipe Grid Coil
• Depending On “T”
Advantages: Branch Loss
– General Guidance: “B”
• Simple System! Length Should Be Twice
That of “A”
• Less Costly Piping
– High Potential of Air
B Binding In Grid
Disadvantages: – Raising Water
Temperature To
Compensate Causes Panel
• Simple System! Flux To Be Too High
• Zone Temperature Control • Guidance: Intertwined
Matched Tagged To Serpentine Coils (Most Pex
Source Production A Based Systems Wind Up This
Way)
12

13. Closed Loop Circulating System Two Pipe, Direct Return
Definition: Elevation Differences
Do Not Cause Flow
Definition: Contact With Air At
One Location Or Less
Two Pipe Distribution System Two Pipe Variable Flow
Riser (Main)
Distribution System
Supply
Advantages: Disadvantages:
Old Balancing Technique;
• 2:1- BRPDR 90% design
Branch • Water Flow Is Variable • Chiller Sees Variable Flow
flow at all terminals
– Saves Pump HP • Flow Through Coil Is
• 1:1- 80%
• Water Coil Provides Better Throttled Creating Variable
Control of Temperature & Return Water Temperature
Humidity To Chiller
• Temperature To Each Coil Is • Must Balance Coil Branches
Return Constant Per Chiller In Relation To Each Other
Riser (Main)
13

14. 2 Pipe Direct Return Has Unequal Differential Pressures Two Pipe Constant Flow Distribution System
Advantages:
100%
Supply • Source Sees “Constant” Flow
• Water Coil Provides Better
Control of Temperature &
Humidity
• Temperature To Coil Is Constant
ΔP3 T
Per Source
Head
ΔP1 ΔP2
Disadvantages:
• Water Flow Is “Constant”
• Flow Through Coil Is Throttled
Creating Variable Return Water
Return Temperature To Source
• More Components: Valves
0 • Must Balance Coil Bypass Pipe ΔP
Distance From Pump
Two Pipe Variable Flow Reverse Return System 2 Pipe Reverse Return Has More Equal Differential Pressures
100%
ΔP1
ΔP2
ΔP3
Head
0
Distance From Pump
14

15. Applying Reverse Return
Calculating Friction Head Loss
• Loads Should All Be Within 25% Of Each Other • hf = Energy Lost Through
Friction Expressed As Fluid
• If Zone Control Is Used, All Branches Should Feet Of Head, Feet Of Fluid
 L V 
2
Flowing
Be In Similar Zones hf  f    
 D  2g  • f= Friction Factor
• You May Still Have To Balance System • L= Length Of Pipe
Darcy-Weisbach Eqn.
• D= Pipe Diameter
• V= Fluid Average Velocity,
Ft/Sec (Flow / Pipe Area)
• g= gravitational constant
5. Size Piping & Calculate Drops Design Criteria For Balanced Piping
 Size Pipes In Branches First
 2-10 FPS / 1’-4.5’ P Per 100’ (Steel)
 Determine Highest Branch Drop & Length Examine Pressure Drops Closely For Hydronic Balance
 Add Coil Drop – Branch To Riser Pressure Drop Ratio Helps System Balance In
Tolerance
 Valve Drop Equal To Coil & Pipe or PICV pressure drop
• 4:1 95% Design Flow All Circuits
 Select Branch To Riser Pressure Drop Ratio
• 2:1 90% Design Flow
 Calculate Mains
• 1:1 80% Design Flow
 Divide Worst Branch PD By Ratio, and Then 2 (S&R)
• Constant Speed Pump
 Divide Riser Total Drop By Pipe Length (Target Design Rate)
 Examine Target Rate • Issues
– Within ASHRAE Guidelines
– Equipment Room Piping
– Enough Pipe Length vs. TEL Of Fittings
 Size Risers – Variable Speed
 Calculate System & Branch Drops
15

16. 240 160 80 240 GPM 160 80 40
100’ 20’ 20’ 100’ B 20’ C 20’
40 GPM 1
40 40 40 30’ 30’
A 80
80 80 80 3 30’ 30’
20’
20 20 20 20 20 20
4 20 20 5
6 2
30’ 30’
30’
Source
Source
40 40 40 40 40 40 40 GPM 40 GPM
30’
30’ 30’
7
8
20 20 20 20 20 20 F
10 20 20 9
30’
80
80 GPM 11
80 80 30’
40 40 40 30’ 30’
40 GPM
100’ E 20’ D 20’ 12
240 160 80 240 GPM 160 80
Flow
Segment A B C 1-2 2-3 3-4-6 3-5-6 6-7 2-8 8-10-11 8-9-11 11-7 7-12 D E F
Calculate Friction Losses
Size
Length
HF Rate
HF Friction Loss
Fittings • Know Length Of Pipe
Service Valves
Coil
Control Valve
– Work Darcy-Weisbach Equation
Balance Valve
Source
– Use Design Tool
Total
• Count Fittings
Path
Path Total
A-1-2-3-4-6-7-12-F – Example: I’m applying stock head loss
A-1-2-3-5-6-7-12-F
A-1-2-8-10-11-7-12-F
A-1-2-8-9-11-7-12-F
– You In Practice: Don’t do this!
• Determine Branch & Riser Losses
A-B-1-2-3-4-6-7-12-E-F
A-B-1-2-3-5-6-7-12-E-F
A-B-1-2-8-10-11-7-12-E-F
A-B-1-2-8-9-11-7-12-E-F
A-B-C-1-2-3-4-6-7-12-D-E-F
– Coils, Specialty Devices
A-B-C-1-2-3-5-6-7-12-D-E-F
A-B-C-1-2-8-10-11-7-12-D-E-F
– Trying To Get Rough Cut for Control & Balance Valves
A-B-C-1-2-8-9-11-7-12-D-E-F
16

17. Copper Pipe Friction Loss Friction Loss Charts
Head Loss Due To Friction, Ft. Per 100 Ft. Pipe
• Published by
ASHRAE &
Hydraulic
Institute
• D/W Eqn.
Add 15%!
Add 15%!
Volumetric Flow Rate, GPM
2”
3¼
Scale 2 Pipe Sizing
Scale 3 Velocity Check
17

18. 2”
3.6
Pipe Sizes
½”-2”
Fitting Pressure Loss
Fitting Loss Pictogram
• Variety of Fitting Loss Methodologies
 Accuracy Varies Widely
 Elbow Equivalents (Least Accurate)
 Total Equivalent Length
 “K” Factor (Current ASHRAE
Recommendation)
V2
Hf = K
2g
18

19. Fitting Pressure Loss How Do Fitting Drops Stack Up?
Rahmeyer “K”
hf hf % TEL hf % K hf
Over Over
GPM TEL “K” “K” K2 K2 hf
2” 90° Steel Elbow (K=1) 15 .04 .03 26 .505 98
<3FPS
20 .07 .03 127 .535 -18
• 1961 H/I TEL 8.5’ 25 .11 .09 24 .535 51
30 .15 .13 18 .543 56
• ASHRAE - H/I “K” Factor 35 .20 .17 15 .552 57
40 .26 .23 15 .561 55
• ASHRAE RP-968 45 .33 .29 15 .57 53
50 .39 .35 .626 45
>11FPS
– (Rahmeyer); K Factor varies 10
widely as a function of 116 1.9 1.91 0 .71 41
velocity
• Organize through spreadsheet Moving Towards Pump Selection…
SEGMENT A B C 1-2 2-3 3-4-6 3-5-6 6-7 2-8 8-10-11 8-9-11 11-7 7-12 D E F
Flow 240 160 80 80 40 20 20 40 40 20 20 40 80 80 160 240
Size
Length
4"
100'
3"
20'
2.5"
20'
2.5
30
1.5 1.25 1.25 1.5
30 60 60 30
1.5
30
1.25
60
1.25
60
1.5
30
2.5
30
2.5"
20'
3" 4"
20' 100' • Friction Losses Unaccounted for;
HF Rate 3 5.5 4.5 4.5 12.5 9 9 12.5 12.5 9 9 12.5 4.5 4.5 5.5 3
– Control Valve
Friction Loss 3 1.1 0.9 1.35 3.75 5.4 5.4 3.75 3.75 5.4 5.4 3.75 1.35 0.9 1.1 3
Fittings 2 2 2 2 2 2 2 2 2 2 2 2
Service Valves 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
Coil 17 17 17 17
Control Valve • Need to understand “controls”
Balance Valve
Source
– Balance Valve
30
Total 5 3.1 2.9 3.35 7.75 26.4 26.4 7.75 7.75 26.4 26.4 7.75 5.35 4.9 5.1 37
PATH
TOTAL • Need to understand “balance”
A-1-2-3-4-6-7-12-F 5 3.35 7.75 26.4 7.75 5.35 37 92.6
A-1-2-3-5-6-7-12-F
– Suction Diffuser
5 3.35 7.75 26.4 7.75 5.35 37 92.6
A-1-2-8-10-11-7-12-F 5 3.35 7.75 26.4 7.75 5.35 37 92.6
A-1-2-8-9-11-7-12-F 5 3.35 7.75 26.4 7.75 5.35 37 92.6
A-B-1-2-3-4-6-7-12-E-F
A-B-1-2-3-5-6-7-12-E-F
5 3.1 3.35 7.75 26.4 7.75 5.35 5.1 37 100.8 • Should understand pumps
5 3.1 3.35 7.75 26.4 7.75 5.35 5.1 37 100.8
A-B-1-2-8-10-11-7-12-E-F 5 3.1 3.35 7.75 26.4 7.75 5.35 5.1 37 100.8
A-B-1-2-8-9-11-7-12-E-F 5 3.1 3.35 7.75 26.4 7.75 5.35 5.1 37 100.8 – Pump Discharge Valve(s)
A-B-C-1-2-3-4-6-7-12-D-E-F 5 3.1 2.9 3.35 7.75 26.4 7.75 5.35 4.9 5.1 37 108.6
A-B-C-1-2-3-5-6-7-12-D-E-F
A-B-C-1-2-8-10-11-7-12-D-E-F
5 3.1 2.9 3.35 7.75 26.4 7.75 5.35 4.9 5.1 37 108.6 • Should understand pumps and systems
5 3.1 2.9 3.35 7.75 26.4 7.75 5.35 4.9 5.1 37 108.6
A-B-C-1-2-8-9-11-7-12-D-E-F 5 3.1 2.9 3.35 7.75 26.4 7.75 5.35 4.9 5.1 37 108.6
19

20. Room Air Re-circulated Automated Control
Heated Room
Controller
Unit Heater
Control Signal
Actuator
Hot Water
Coil Blower
Add Valves
Automated Control Theory
Energy is lost
Energy is lost
Disturbances
proportionally to
proportionally to
the outside
the outside Heat Gains • Solar
temperature
temperature • Change Weather
q = UA(Ti-TO) )
q = UA(T -T
i O
• People
Manipulate Coil
Control
Water Blower Temperature
The controller output signal
Flow
Process
The controller output signal
acts in a proportional manner
acts in a proportional manner
to the difference in the actual
to the difference in the actual
from the desired temperature
from the desired temperature
adding what is lost
adding what is lost
20

21. Theory A Fairly Simple Concept...
Disturbances • Unaccounted for
Changes In • We control for comfort as indicated by
Heat Gains Differential Head
• Friction Head Loss temperature
Water Flow
Distribution
Air Flow • Pressure Control – Humidity Control “Implied” By Coil Selection
Dynamics
• Various levels of implementation
Manipulate Coil – Economic Criteria
Control
Water Blower Temperature – Process Criteria
Flow
Process – Paradigm Criteria
Proportional Control Proportional Control
SP + e t
K Ke
e
ns
MV - e
po
0-10 VDC
Output
es
Output
Error 0-10 VDC
rR
Signal SP Control Signal
ea
Lin
“Control Theory”
e - Error y
0-10 VDC
t
Output
0-10 VDC
SP Control Signal
Room Controller
Room Controller
Actuated Valve
Actuated Valve
21

22. Proportional Control Traditional 2 Way Valve Temperature Control
M C • Controller controls
y because response
t
is predictable
0-10 VDC
Output
0-10 VDC
SP Control Signal
T
• Variable coil flow
Room Controller
• Variable system
y flow
• “Why” variable
(y-yi)=K(t-ti) speed pumping
Actuated Valve
can be used
y = Valve Position
yi = Initial Valve Position
t = Temperature
ti = Initial Temperature
K = Constant (gain)
Valve Characteristic • ASHRAE Research (RP-5) Boiled It Down To This
100%
– Just About Every HVAC Text On Valves Uses This Type of Figure
Quick Opening
90%
– The Coil Gain (Proportional Band) Isn’t the Same As The
80% Controllers… Why We Use An Equal Percentage Valve
70%
Controlled
Coil Characteristic Valve Characteristic Relationship
% Branch Flow
60%
Linear n
50% Ga i
40%
in
Ga
30%
in
Ga
20%
Gain
10%
Equal Percentage
0%
0% 20% 40% 60% 80% 100%
% Valve Lift Source: ASHRAE Handbook
22

23. Linear Stem Valves (Globe) Controllability ~ Constants
• Constant Differential Pressure Keeps Predictable
Flow Characteristic
Coil 1%
8%
To Select Properly;
• Required Flow Rate (GPM)
• Select Differential Pressure
TC Valve
– Magnitude Depends On; Throttle In
• Control; Open-Closed/Modulating Here 90% Time
• Hydraulic Design Philosophy; Balanced,
Unbalanced, Branch & Riser Pressure
Drops
• Pump Control; Constant vs. Variable
Speed
• Required Valve Authority
– Consider Characteristic Requirement
Adjustment Proportional Action
THROTTLING %
100
0% 10% 100% • Two Position
POSITION OF CONTROLLED DEVICE
Room Temperature
75 Set
Point
% OF STROKE
50
25
Valve Position
Open
0
0 25 50 75 100
CONTROLLED VARIABLE
% OF CONTROLLER SCALE
23

24. Proportional Action Valve Description
• Proportional Positioning
• Many terms describe valves
Room Temperature
• Flow Coefficient
Set
Offset Point – CV
– Rangeability
Open
Valve Position
Closed
Control Valve Integration Flow Coefficient
EQUAL PERCENTAGE CHARACTERISTIC
100
75
% OF FLOW
50
25
y
0
0 25 50 75 100
ΔP
q  CV
% OF VALVE
STROKE
SG
24

25. Flow Coefficient
Rangeability
Max Flow
Q  q  500(t ent  t lvg ) Heat Transfer
Min Flow
• With & W/O Actuator
ΔP Units = PSI • Without Actuator, 30:1
Flow q  CV • With Actuator, 100+:1
SG Water = 1 • Globe Valves “De-Facto”
Standard
• Ball Valve…
Calculate Desired
Live with Available
The Goal; Make the red line straight and 100% to 100%
Authority
100%
istic
Ch
ar act
er
• Valve authority affects controllability
C oil
80%
• The Controller cannot control properly
ic
ist
 = PMIN /  PMAX
rity
er
ct
t ho
ra
ha
60%
Au
lC
Return
Supply
%
ro
tic
nt
50
Co
ris
te
40%
ac
ar
Ch
PENT
%
Eq
20%
PMAX PMIN
Maximum
Valve Stroke
0%
0% 20% 40% 60% 80% 100% 120% 140%
PLVG
25

26. Valve Authority Valve Characteristic and Authority
100%
Return
Supply
90%
80%
.1
70%
=
β
% Branch Flow
.3
60%
.50
β=
1. 0
50%
=
β
β=
40%
CV2 CV1 CV2 30%
 Constant Flow Coefficient 20%
Valve Specification
C V1  C V2
Valve Specification
 Pipe 10%
• Modified Equal Percentage Valve
• Modified Equal Percentage Valve
• Globe Pattern
C VSYS 
• Globe Pattern
 Coil • 2” Size
• 2” Size
• 30:1 Rangeability
 Service Valves 0%
• 30:1 Rangeability

 Balancing Valves
Variable: Control Valve
C2  C2
V1 V2
0% 20% 40% 60% 80% 100%
% Valve Lift
Selection Understand Hydraulics
• Required Flow Rate (GPM) 100%
• Select Differential Pressure ΔP1
ΔP2
– Magnitude Depends On;
• Control; Open-Closed/Modulating
Head
• Hydraulic Design Philosophy; Balanced, ΔP1+ΔP2 ΔP2 ΔP3
Unbalanced, Branch & Riser Pressure Drops
• Pump Control; Constant vs. Variable Speed
• Required Valve Authority
– Consider Characteristic Requirement
0
• Solve Algebraically Distance From Pump
26