basic traininghydronics by belimo

© BELIMO Aircontrols Basic Hydronic Training 1

Belimo Aircontrols, Inc. (USA)

Basic Hydronic Training


System Components


Components in a Hydronic System

1. Pump

2. Load

3. Control Valve

4. Balancing Valve

5. Source

6. Air Removal System

7. Expansion Unit

17

3

4

5

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2

6


Source Carrier Load

Source Load

Water, Air, Refrigerant, Electricity

Heating Load

Cooling LoadHeating

Cooling


Hydronic Systems

Ch

ille

r

Co

oli

ng

Co

il

40F

43F

45F

55F57FB

oil

er

He

ati

ng

Co

il

250F

245F

240F

190F185F

Cooling Heating


Water Systems

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Expansion

Chamber

Closed System Open System

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Closed Water Systems

• Low Temperature Water (LTW)

- Max. 160PSI and max. 250F

• Medium Temperature Water (MTW)

-Max. 160PSI / 250F to 350F

• High Temperature Water (HTW)

-Max. 300 PSI and max. 350F

• Chilled Water Systems (CWS)

- Max. 120 PSI / 40F to 55F (44F or 45F)


Piping Circuits

• Two Pipe System

• Three Pipe System

• Four Pipe System

• Direct and Reverse Return Systems

• Primary-Secondary System


Two Pipe System

• Main Supply Chilled Water or Heat Water

• Supply one pipe, Return one pipe

• Cooling or heating at source

• Loads must all require cooling or heating

coincidentally


Two Pipe SystemB

oile

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Ch

ille

r

Lo

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Two Pipe System


Three Pipe SystemB

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Ch

ille

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Three Pipe System


Three-Pipe System


Four Pipe System


Four Pipe System with One Coil


Four Pipe System with H&C Coil


Cost for Four Pipe System

• High first cost due to the second water system and the

need for either two coils or more costly control valves

at each terminal unit.

• High operating cost due to the two pumps operating,

but do provide good flexibility in meeting varying loads.


• All year availability of heating and cooling with individual

zone temperature control

• Chilled and hot water are typically only simultaneously

supplied during the Spring and Fall seasons

• Elimination of zoning cost and complexity

Simpler changeover decisions

• The lowest and quietest fan speed is adequate most of

the time.

Advantages of Four Pipe Systems


Coil #4

0 - 100 gpm

Coil #3

0 - 100 gpm

Coil #1

0 - 100 gpm

Coil #2

0 - 100 gpm

Source

Piping - Direct Return Piping


Coil #4

0 - 100 gpm

Coil #3

0 - 100 gpm

Coil #1

0 - 100 gpm

Coil #2

0 - 100 gpm

Source

Piping - Reverse Return Piping


Primary – Secondary SystemS

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Pipe Design


.constpp dynstat

Bernoulli’s Law

The Bernoulli’s law is stating the principle of

energy conservation. The sum of the two energies

represented by static pressure and dynamic

pressure is constant between two points in the

pipe, assuming no energy exchange with the

exterior or transformation of energy into heat by

friction between these two points.


Bernoulli’s Law

ptotal1

ptotal2

pstatic1 pstatic2

pdyn1 pdyn2


V2 P2 2

V1 P1 1

Z1

Z2

hL

LhP

g

VZ

P

g

VZ

2

2

2

22

1

1

2

11

22


Pipe Sizing and Pressure Drop Equations

g

V

D

Lfh

2

2

Darcy-Weisbach Equation

2ft/sec 32.2 constan, nalgravitatio g

ft/sec velocity,average Fluid

in pipe, ofDiameter Internal D

ft pipe, ofLength L

)Moody (from essdimensionl factor,friction f

ftin drop, pressureΔh

V


Sizing a Piping System Pipe Friction Loss

• Suggested head loss in range from 1 to 4ft per 100ft

- 1997 ASHRAE Handbook-Fundamentals

• Max. 4 ft/sec velocity in pipe 2”

• Suggested 4 ft/sec velocity in pipes larger than 2”


Simplified Method

• D = Pipe Diameter

• Q = Flow Rate, GPM

• S = Pipe Sizing Constant

- S= 0.44, assuming 4 ft head drop/100ft

- S = 0.5 assuming 2 ft head drop/ 100ft

4.0QSD


Examples

Load: 100GPM

D = SQ0.4 = 0.44 x 1000.4 = 2.78” 3”

Load: 200GPM

D = SQ0.4 = 0.44 x 2000.4 = 3.66” 4”

Load: 300GPM

D = SQ0.4 = 0.44 x 3000.4 = 4.31” 4”

Load: 400GPM

D = SQ0.4 = 0.44 x 4000.4 = 4.83” 5”


Head Loss Calculation

Pipes (Friction Loss for Water in Commercial Steel Pipe

(Schedule 40)

Strainers, Fitting, Elbows, Reduction, etc

Valves, Balancing Valves (Valve - Manufacturer)

Head loss Load (Coil, etc.)

Head loss Source (Chiller, etc.)

=Total Head Loss


Head Loss in Pipes

Pipes (Friction Loss for Water in

Commercial Steel Pipe (Schedule 40)

Head Loss

2.5ft

Flo

w R

ate

10

0G

PM

hspec =…ft/100ft pipe

Total h=L x hspec /100


Fittings

h = head loss in feet of water

k = resistance coefficient for valve or fitting

V2/2g = velocity head, ft based on flow gpm in connect pipe (example Figure

2 – 15 for 2 in)

V = fluid velocity, ft/sec

g = 32.2 ft/sec2, gravitational constant

g

Vkh

2

2


Which pump do we choose?

Total Pipe length = 300 ft

BTU/HR = 500,000 BTU/HR

T = 10F

GPM = ?

Ch

ille

r

Co

il

500T

BTUHGPM

GPMxT

BTUHGPM 100

50010

500000

500


What is the pipe size?

Required Flow: 100GPM

Pipe Diameter: ?

D = Pipe Diameter

Q = Flow Rate, GPM

S = Pipe Sizing Constant

S= 0.44, assuming 4 ft head loss/100ft

S = 0.5 assuming 2 ft head loss/ 100ft

4.0QSD D = SQ0.4 = 0.44 x 1000.4 = 2.78” 3”


Head loss elbows?

Pipe: 3”, Steel Pipe, screwed

Head loss of total elbows?

Ch

ille

r

Co

il

4 Elbow 0.8ft

g

Vkh

2

2

fth 2.02.322

48.0

2


Head loss pipe?

Pipe: 3”, Steel Pipe, screwed

Total Pipe length = 300 ft

Ch

ille

r

Co

il

h = 300 x 2.5 /100 = 7.5ft

Pipes (Friction Loss for Water in Commercial Steel Pipe (Schedule 40)Figure 2-14 Friction Loss - Water

2.5 ft/100ft


Total head loss?

1 Chiller 9 ft (4PSI, Info Manuf.)

1 Cooling Coil 9 ft (4PSI, Info Manuf.)

1 Control Valve 9 ft (4PSI)

1 Balance Valve 3 ft (1PSI)

4 Elbows each 0.2 ft 0.8 ft

1 Pipe System 7.5 ft

Ch

ille

r

Co

il

Total Head Loss of 38.3ft at 100GPM


System Curve

0 80 120 160 200

10

20

40

60

80

20 40 60 100 140 180

Flow – GPM

Head (

ft) System Point at

design load

Head Loss of 38.3 at 100GPM


Pumps in HVAC


Pumps in HVAC

Single Suction Double Suction

Volute Type Axial Flow Type

Centrifugal Special Effect

Dynamic

Reciprocating Rotary Pumps

Displacement

Pumps


Impeller

BladeInlet

Flow

Outlet Flow


Pump Curve

V

Pump Characteristic

100% Volume

Operating Point

Pump

Head

System

Head

Ch

ille

r

Co

il


Pump Curve (Steep)

p

V

Pump Characteristic

100%Volume

Operating Point

Ch

ille

r

Co

il


Pump Curve (Flat)

p

V

Pump Characteristic

100%

Ch

ille

r

Co

il

25%

Volume

Operating Point


Operating Point

p

V

Load 100% Flow

100%

Ch

ille

r

Co

il Operating Point

System Head

Curve

Pump Head

Capacity Curve


System Curves for a Pump Type

0 80 120 160 200

10

20

40

60

80

20 40 60 100 140 180

Flow – GPM

Head (

ft)

70%65%60%7.0

6.5

6.0

5.5

5.0

Motor Horsepower

55%


Minimum Flow of Pump

• Depends on pump construction and energy generated

by pump

• Not enough flow could result in overheating and

cavitation

• Some low power pumps can operate at zero flow

• Installation of bypass circuit


Valves in HVAC


What Control Characteristic is Preferred?

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Control Signal (%)

Hea

t O

utp

ut

(%)

Heat Output


What are the Coil Characteristics?

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Valve Opening (%)

Heat O

utp

ut

(%)

Characteristic of

a coil

Heat Output


What are the Valve Characteristics?100

0 40 60 80 100

20

40

60

80

10

30

50

70

90

10 20 30 50 70 90

Signal (%)

Flo

w,

Heat O

utp

ut (%

)

Heat Output

Characteristic of

a Coil

Characteristic of

Control Valve


Valve Opening (Signal) (%)

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Flo

w (

%)

10.7

Equal %

010.70

6.513.410

131720

19.52130

262640

333350

414160

515170

646480

808090

100100100

Corrected

Flow

Theoretical

Flow

Lift

Linear Curve

Valve Characteristics

Modified Equal Percentage


Valve Authority


Authority of Control Valves

with Variable Flow Through the Coil

• Authority of two way control valves

• Authority of three way control valves


3-way Control Valve

Const

4 4 12

5.08

4A

leFlowVariabv

v

pp

pA

100

100

0

100

v

v

p

pA

20 psi


3-way Control Valve

Const

20 psi

4 4 12

5.08

4A

leFlowVariabv

v

pp

pA

100

100

0

100

v

v

p

pA

A

B


3-way Control Valve

Const

41 45 121450%

01

20 psi


Valve Authority - Flow 100%P

Term

inal

P V

alv

e

Coil

P Terminal =const



Term

inal

P V

alv

e

Coil

P Terminal =const


2.020

4A

leFlowVariabv

v

pp

pA

100

100

0

100

v

v

p

pA

2-way Control Valve

VFD

4 4 12

20 psi


2-way Control Valve

VFD

41 416 123

20 psi

50%


Valve Authority - Flow 100%

Coil

P T

erm

inal

P V

alv

e



Coil

P T

erm

inal

P V

alv

e



Coil

P T

erm

ina

l

P V

alv

e

P Terminal =const


Sizing Rules

Min. pvalve = 0.25 p pumphead

Authority = 0.4 to 0.5


Authority Distortion of Linear Flow

Characteristics

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Valve Opening (%)

Flo

w (

%)

0.1

0.2

0.4

0.6

0.8

1


Authority Distortion of Equal Percentage

Flow Characteristics

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Valve Opening (%)

Flo

w (

%)

0.1

0.2

1

0.4

0.6

0.8


Counter-flow, cross-flow or parallel-flow heat exchangers are used

depending on the application. They have different efficiencies.

Counter-Flow Cross-Flow Parallel-Flow


Constant or Variable Flow

Regardless of valve position, the

full water flow is always circulating

through the heat exchanger

=> Temperature control

Depending of valve position,

0..100% of the water flow

circulates through the heat

exchanger

=> Flow control

e.g. air


Large outside flow?

Temperature control

constant Flow

Variable temperature

Are different temperature

levels in coil acceptable?

Flow Control

Constant Temperature

Variable Flow

yes

no

yes

Constant or Variable Flow

Dehumidification

yes

no

yes yes

Prevention of

freezing

nono


Diverting Circuit with Mixing Valve

pV100

pFV

Coil

100%100%

var

var

var


Diverting Circuit with Diverting Valve

pV100

pFV

Coil

100%100%

var

varvar


Throttling Circuit

pV100

pFV

Coil

varvar


Mixing Circuit with Mixing Valve

pv100

Coil

100%100%

var

varvar


Application a-Value

Pre Heating Coil

0.25 to 0.4

Heating Coil 0.15 to 0.4

Cooling Coil 0.25 to 0.5

Radiators 0.5 to 0.65

Converters 0.5 – 3.0

0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Flow (%)

Energ

y (

%)

3

21.5

10.8

0.60.4

0.05

0.15

0.25

Heat Exchanger Characteristics


0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Flow (%)

Ene

rgy (

%)


Constant Flow

Variable Flow


0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Flow (%)

Ene

rgy (

%)


T = 10F

T = 30F


0 40 60 80 100

20

40

60

80

100

10

30

50

70

90

10 20 30 50 70 90

Flow (%)

Ene

rgy (

%)


Heating Coil

Cooling Coil


Influencing Factors

Base Valve

Characteristic

Hydraulic

System

System Valve

CharacteristicCoil

Characteristic

Resulting

Characteristic

Valve with

Hydraulics

Heat

Exchanger


Conventional Sizing Methods


Coil #4

0 - 100 gpm

Coil #3

0 - 100 gpm

Coil #1

0 - 100 gpm

Coil #2

0 - 100 gpm

20 psi

30 psi

40 psi

p =4 psi

p =4 psi

p=4 psi

p=4 psi

p=12 psi

p=2 psi

p=32 psi

p=22 psi

Pressure Differential Sensor

Chiller

20 psi

p=4 psi

p=4 psi

p=4 psi

p=4 psi

VFD-Pump

10 psi10 psi

30 psi

40 psi

Application


A=4/10=0.4

A=4/20=0.2

A=4/30=0.14

A=4/40=0.1

Signal

Flo

w/H

ea

t o

utp

ut %

Coil #4

0 - 100 gpm

Coil #3

0 - 100 gpm

Coil #1

0 - 100 gpm

Coil #2

0 - 100 gpm

20 psi

30 psi

40 psi

p=12 psi

p=2 psi

p=32 psi

p=22 psi


Chiller

p=4 psi

p=4 psi

p=4 psi

p=4 psi

VFD-Pump

10 psip =4 psi

p =4 psi

p=4 psi

p=4 psi

Application

Authority


Shift to Variable Supply with VFD-Pumps

and Two-way Valves

Const

20 psi

4 4 12

VFD

20 psi

44

12


Authority Method


A=0.5

A=0.5

A=0.5

A=0.5

Signal

Flo

w/H

ea

tou

tpu

t

Coil #1

0 - 100 gpm

Coil #2

0 - 100 gpm

Coil #4

0 - 100 gpm

Coil #3

0 - 100 gpm

20 psi

30 psi

40 psi

p=6 psi

p=2 psi

p=16 psi

p=11 psi


Chiller

p=4 psi

p=4 psi

p=4 psi

p=4 psi

VFD-Pump

10 psip =4 psi

p =10psi

p=15 psi

p=20 psi

Application


Current Concepts for Valve Sizing

Correct sized components

Generally less expensive components, like valves

Complex procedures for all involved

More detailed information is required

Consideration of diversity factors

No feedback of sized devices from suppliers

Very simple rule

Used by all involved in the project

Good base for price comparison

Oversized valves overpriced valves

Bad authority

Hunting

Instable control loops

Exact

calculation

f( p and V)

Rule:

pvalve = pCoil

Rule:

pvalve= 3 – 5 psi


Additional Valve Sizing Considerations

For the selection of the valve bodies it is

necessary to consider elevation of

system, pump pressure and fill pressure

Two-way valves:

• For the close-off pressure the pump

head needs to be considered.

Three-way valves:

• Pressure difference valve


Reference Literature

• Total Hydronic Balancing

Robert Petitjean, Tour & Andersson Hydronic AB

• HVAC Pump Handbook

James B. Rishel, McGraw-Hill

• ASHRAE Handbooks

• HVAC Equations, Data, and Rules of Thumb

Bell, McGraw-Hill


Thank You

basic traininghydronics by belimo

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