Lecture Objectives:

1
Lecture Objectives

• Learn about
• Pumps and
• System Curves

2
Hydronic Terms

• Head loss
• Open-loop vs. closed loop

• Open System
• Closed System

h
Pump
Cooling coil in AHU
Chiller
Pump
3
Is this open or closed system ?
Cooling towers
4
Relationship between velocity in a pipe and
pressure drop
?p v2 ?p Constant v2
Required power (P) for the pump
P V ?p P power W,
V volume flow rate m3/s,
v velocity m/s
?p pressure drop Pa
?p v2 (?p V2 when same pipe
is used) P V V2 when same pipe is used P
V3 P2/P1 (V2/V1)3 For the same
pipe When different pipe is used for the same
flow rate For the same flow rate V Reduction of
D
smaller pipe
larger pipe
?p Pa or ft water
P2/P1 (D1/D2)4 - for the same flow rate or
50 smaller diameter of the pipe for the same
flow rate wee have 4 times larger velocity 16
times larger pressure drop and 16 times lager
power for the pump
v m/s or fpm
5
Head Loss
6
Fittings
7
Pumps

• Raise pressure and produce flow
• Main type
• Centrifugal

Example of Turbine pump
Base mounted
Inline
Reading (textbook) Page 3-36 - 3-45
8
Pump curves

• NPSHR Net Positive Suction Head Required

9
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10
Changing Pump Speed
11
Net Positive Suction Head(cavitation)
12
Curve for Multiple Pumps
13
System Curves
?p
?p
AB
AB
B
A
B
A
V
A
B
V
A
B
Parallel
Serial
14
Find a system curve for this plumbing
configuration
15
Primary/Secondary and Tertiary Pumping
(schematics AB below)
16
System balancing
AHU1
AHU2
HC1
HC2
100 ft
1000 ft
10 gpm
2 gpm
10 ft
pump
BOILER
17
Valves

• Section 5-14 and 6-15 in the textbook
• Types
• Butterfly Valves
• Ball Valves
• Globe Valves
• Three way valves

18
Valve Sizing and Flow Coefficient
Cv value
in liter/hour or.
in Pa
Control Valve Selection For Hydronic Systems
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19
Control Valve Selection For Hydronic Systems
We tried to do this
Valve authority
20
HW2
40 ft
20 ft
20 ft
200 ft
5 ft
30 ft
30 ft
200 ft
40 ft
10 ton
30 ft
20 ft
10 ft
5 ft
5 ft
10 ft
10 ft
5 ft
30 ft
10 ft
5 ft
5 ft
10 ton
21
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