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© BELIMO Aircontrols Basic Hydronic Training 1
Belimo Aircontrols, Inc. (USA)
Basic Hydronic Training
© BELIMO Aircontrols Basic Hydronic Training 2
System Components
© BELIMO Aircontrols Basic Hydronic Training 3
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
Sourc
e
Lo
ad
2
6
© BELIMO Aircontrols Basic Hydronic Training 4
Source Carrier Load
Source Load
Water, Air, Refrigerant, Electricity
Heating Load
Cooling LoadHeating
Cooling
© BELIMO Aircontrols Basic Hydronic Training 5
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
© BELIMO Aircontrols Basic Hydronic Training 6
Water Systems
So
urc
e
Lo
ad
Expansion
Chamber
Closed System Open System
So
urc
e
Lo
ad
© BELIMO Aircontrols Basic Hydronic Training 7
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)
© BELIMO Aircontrols Basic Hydronic Training 8
Piping Circuits
• Two Pipe System
• Three Pipe System
• Four Pipe System
• Direct and Reverse Return Systems
• Primary-Secondary System
© BELIMO Aircontrols Basic Hydronic Training 9
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
© BELIMO Aircontrols Basic Hydronic Training 10
Two Pipe SystemB
oile
r
Lo
ad
Ch
ille
r
Lo
ad
Lo
ad
© BELIMO Aircontrols Basic Hydronic Training 11
Two Pipe System
© BELIMO Aircontrols Basic Hydronic Training 12
Three Pipe SystemB
oile
r
Lo
ad
Ch
ille
r
Lo
ad
Lo
ad
© BELIMO Aircontrols Basic Hydronic Training 13
Three Pipe System
© BELIMO Aircontrols Basic Hydronic Training 14
Three-Pipe System
© BELIMO Aircontrols Basic Hydronic Training 15
Four Pipe System
© BELIMO Aircontrols Basic Hydronic Training 16
Four Pipe System with One Coil
© BELIMO Aircontrols Basic Hydronic Training 17
Four Pipe System with H&C Coil
© BELIMO Aircontrols Basic Hydronic Training 18
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.
© BELIMO Aircontrols Basic Hydronic Training 19
• 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
© BELIMO Aircontrols Basic Hydronic Training 20
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
© BELIMO Aircontrols Basic Hydronic Training 21
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
© BELIMO Aircontrols Basic Hydronic Training 22
Primary – Secondary SystemS
ou
rce
Lo
ad
So
urc
e
So
urc
e
Lo
ad
Lo
ad
© BELIMO Aircontrols Basic Hydronic Training 23
Pipe Design
© BELIMO Aircontrols Basic Hydronic Training 24
.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.
© BELIMO Aircontrols Basic Hydronic Training 25
Bernoulli’s Law
ptotal1
ptotal2
pstatic1 pstatic2
pdyn1 pdyn2
© BELIMO Aircontrols Basic Hydronic Training 26
V2 P2 2
V1 P1 1
Z1
Z2
hL
LhP
g
VZ
P
g
VZ
2
2
2
22
1
1
2
11
22
© BELIMO Aircontrols Basic Hydronic Training 27
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
© BELIMO Aircontrols Basic Hydronic Training 28
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”
© BELIMO Aircontrols Basic Hydronic Training 29
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
© BELIMO Aircontrols Basic Hydronic Training 30
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”
© BELIMO Aircontrols Basic Hydronic Training 31
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
© BELIMO Aircontrols Basic Hydronic Training 32
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
© BELIMO Aircontrols Basic Hydronic Training 33
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
© BELIMO Aircontrols Basic Hydronic Training 34
© BELIMO Aircontrols Basic Hydronic Training 35
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
© BELIMO Aircontrols Basic Hydronic Training 36
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”
© BELIMO Aircontrols Basic Hydronic Training 37
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
© BELIMO Aircontrols Basic Hydronic Training 38
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
© BELIMO Aircontrols Basic Hydronic Training 39
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
© BELIMO Aircontrols Basic Hydronic Training 40
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
© BELIMO Aircontrols Basic Hydronic Training 41
Pumps in HVAC
© BELIMO Aircontrols Basic Hydronic Training 42
Pumps in HVAC
Single Suction Double Suction
Volute Type Axial Flow Type
Centrifugal Special Effect
Dynamic
Reciprocating Rotary Pumps
Displacement
Pumps
© BELIMO Aircontrols Basic Hydronic Training 43
Impeller
BladeInlet
Flow
Outlet Flow
© BELIMO Aircontrols Basic Hydronic Training 44
Pump Curve
V
Pump Characteristic
100% Volume
Operating Point
Pump
Head
System
Head
Ch
ille
r
Co
il
© BELIMO Aircontrols Basic Hydronic Training 45
Pump Curve (Steep)
p
V
Pump Characteristic
100%Volume
Operating Point
Ch
ille
r
Co
il
© BELIMO Aircontrols Basic Hydronic Training 46
Pump Curve (Flat)
p
V
Pump Characteristic
100%
Ch
ille
r
Co
il
25%
Volume
Operating Point
© BELIMO Aircontrols Basic Hydronic Training 47
Operating Point
p
V
Load 100% Flow
100%
Ch
ille
r
Co
il Operating Point
System Head
Curve
Pump Head
Capacity Curve
© BELIMO Aircontrols Basic Hydronic Training 48
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%
© BELIMO Aircontrols Basic Hydronic Training 49
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
© BELIMO Aircontrols Basic Hydronic Training 50
Valves in HVAC
© BELIMO Aircontrols Basic Hydronic Training 51
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
© BELIMO Aircontrols Basic Hydronic Training 52
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
© BELIMO Aircontrols Basic Hydronic Training 53
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
© BELIMO Aircontrols Basic Hydronic Training 54
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
© BELIMO Aircontrols Basic Hydronic Training 55
Valve Authority
© BELIMO Aircontrols Basic Hydronic Training 56
Authority of Control Valves
with Variable Flow Through the Coil
• Authority of two way control valves
• Authority of three way control valves
© BELIMO Aircontrols Basic Hydronic Training 57
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
© BELIMO Aircontrols Basic Hydronic Training 58
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
© BELIMO Aircontrols Basic Hydronic Training 59
3-way Control Valve
Const
41 45 121450%
01
20 psi
© BELIMO Aircontrols Basic Hydronic Training 60
Valve Authority - Flow 100%P
Term
inal
P V
alv
e
Coil
P Terminal =const
© BELIMO Aircontrols Basic Hydronic Training 61
Valve Authority - Flow 50%P
Term
inal
P V
alv
e
Coil
P Terminal =const
© BELIMO Aircontrols Basic Hydronic Training 62
Valve Authority - Flow 0%P
Term
inal
P V
alv
e
Coil
P Terminal =const
© BELIMO Aircontrols Basic Hydronic Training 63
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
© BELIMO Aircontrols Basic Hydronic Training 64
2-way Control Valve
VFD
41 416 123
20 psi
50%
© BELIMO Aircontrols Basic Hydronic Training 65
Valve Authority - Flow 100%
Coil
P T
erm
inal
P V
alv
e
© BELIMO Aircontrols Basic Hydronic Training 66
Valve Authority - Flow 50%
Coil
P T
erm
inal
P V
alv
e
© BELIMO Aircontrols Basic Hydronic Training 67
Valve Authority - Flow 0%
Coil
P T
erm
ina
l
P V
alv
e
P Terminal =const
© BELIMO Aircontrols Basic Hydronic Training 68
Sizing Rules
Min. pvalve = 0.25 p pumphead
Authority = 0.4 to 0.5
© BELIMO Aircontrols Basic Hydronic Training 69
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
© BELIMO Aircontrols Basic Hydronic Training 70
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
© BELIMO Aircontrols Basic Hydronic Training 71
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
© BELIMO Aircontrols Basic Hydronic Training 72
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
© BELIMO Aircontrols Basic Hydronic Training 73
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
© BELIMO Aircontrols Basic Hydronic Training 74
Diverting Circuit with Mixing Valve
pV100
pFV
Coil
100%100%
var
var
var
© BELIMO Aircontrols Basic Hydronic Training 75
Diverting Circuit with Diverting Valve
pV100
pFV
Coil
100%100%
var
varvar
© BELIMO Aircontrols Basic Hydronic Training 76
Throttling Circuit
pV100
pFV
Coil
varvar
© BELIMO Aircontrols Basic Hydronic Training 77
Mixing Circuit with Mixing Valve
pv100
Coil
100%100%
var
varvar
© BELIMO Aircontrols Basic Hydronic Training 78
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
© BELIMO Aircontrols Basic Hydronic Training 79
0 40 60 80 100
20
40
60
80
100
10
30
50
70
90
10 20 30 50 70 90
Flow (%)
Ene
rgy (
%)
Heat Exchanger Characteristics
Constant Flow
Variable Flow
© BELIMO Aircontrols Basic Hydronic Training 80
0 40 60 80 100
20
40
60
80
100
10
30
50
70
90
10 20 30 50 70 90
Flow (%)
Ene
rgy (
%)
Heat Exchanger Characteristics
T = 10F
T = 30F
© BELIMO Aircontrols Basic Hydronic Training 81
0 40 60 80 100
20
40
60
80
100
10
30
50
70
90
10 20 30 50 70 90
Flow (%)
Ene
rgy (
%)
Heat Exchanger Characteristics
Heating Coil
Cooling Coil
© BELIMO Aircontrols Basic Hydronic Training 82
Influencing Factors
Base Valve
Characteristic
Hydraulic
System
System Valve
CharacteristicCoil
Characteristic
Resulting
Characteristic
Valve with
Hydraulics
Heat
Exchanger
© BELIMO Aircontrols Basic Hydronic Training 83
Conventional Sizing Methods
© BELIMO Aircontrols Basic Hydronic Training 84
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
© BELIMO Aircontrols Basic Hydronic Training 85
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
Pressure Differential Sensor
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
© BELIMO Aircontrols Basic Hydronic Training 86
Shift to Variable Supply with VFD-Pumps
and Two-way Valves
Const
20 psi
4 4 12
VFD
20 psi
44
12
© BELIMO Aircontrols Basic Hydronic Training 87
Authority Method
© BELIMO Aircontrols Basic Hydronic Training 88
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
Pressure Differential Sensor
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
© BELIMO Aircontrols Basic Hydronic Training 89
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
© BELIMO Aircontrols Basic Hydronic Training 90
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
© BELIMO Aircontrols Basic Hydronic Training 92
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
© BELIMO Aircontrols Basic Hydronic Training 93
Thank You