1

Hospital Building and Campus Piping

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Hospital Building

Occupancy – office and patient areas• Patient areas: 24 hours per day• Office areas: 8 am – 5 pm, Monday - Friday

Building Characteristics:• Four story with basement• 140,000 square feet per floor• Standard construction

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Hospital – Stand alone operation

• Larger building• Larger pumps• Similar applications

4

Medical Complex with Central Plant

• All buildings served from a single heating and cooling source located in a central plant• Hot and chilled water are distributed to each building via piping loops

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Medical Complex with Central Plant

Similarities • All previous examples can exist in the same or larger scale

Differences• Pumps may be larger• Distribution piping can be different

• Location of central plant is critical

• Multiple central plants may be tied together

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Campus Piping Systems

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Types of Piping Systems

Closed Loop Systems• Chilled Water Systems• Hot Water Systems

Open Loop System• Condenser Water Systems• Domestic Hot Water Recirculation• Domestic Pressure Boosting (future session)

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Two Pipe Direct Return

CHILLER

CHILLER

CHILLER

Return

Supply

PumpController

Secondary Pumps

Primary Pumps Expansion TankAir Separator

CommonPipe

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Two Pipe Direct Return

Common applications• Basis of design for most CHW systems.• Small, medium, or large size buildings• Low or high rise• Single or multiple buildings• Single supply temperature

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Two Pipe Direct Return

Piping Tips• Common pipe design• Tank

• Point of No Pressure Change (PNPC)• Warmest water

• Air control and relief• 2-way valves

• Size• Location

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Two Pipe Direct Return

Advantages• Simplicity• First Cost• Efficient

Disadvantages• Over-pressurization• Balancing• Head requirement• Thermally linked

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Primary-Secondary-Tertiary

CHILLER

CHILLER

Zone A

Zone B

Zone C

Optional Variable Speed Pump ∆P Sensor

ModulatingControl Valves

Secondary Pump

CHILLER

Primary Pumps

Tertiary Pumps

Common Pipe

Common Pipe

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Primary-Secondary-Tertiary

Common applications• Multi-building campuses• Campuses with large diversity• Campuses with buildings of varying heights• Campuses with long piping runs• Campuses with multiple production plants• Campuses with elevation changes

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Tertiary Loop Piping

T3

T1

Load

Load

MV

Load MV

Common PipeT2

TertiaryZonePumps

Tertiary BridgeSecondary Pump(s)

Secondary ChilledWater Return

Small BypassMaintains AccurateTemperature Reading

Magna3T3

T1

LoadMV

LoadMV

Load MV

Common PipeT2

TertiaryZonePump

Tertiary BridgeSecondary Pump(s)

Secondary ChilledWater Return

Magna3

MV

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Primary-Secondary-Tertiary w/Plate HX

Expansion TankAir Separator

Expansion TankAir Separator

CHILLER

CHILLER

Optional VS Pump ∆P Sensor

ModulatingControl Valves

Secondary Pump

CHILLER

Primary Pumps

Magna3

Common Pipe

Plate HX Plate HXPlate HX

Tertiary Pumps

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Tertiary Loop Piping w/ Plate HX

Small BypassMaintains AccurateTemperature Reading

T3

T1

Load

Load

MV

Load MV

T2

TertiaryZonePumps

Tertiary BridgeSecondary Pump(s)

Secondary ChilledWater Return

Small BypassMaintains AccurateTemperature Reading

Magna3T3

T1

LoadMV

LoadMV

Load MV

T2

TertiaryZonePump

Tertiary BridgeSecondary Pump(s)

Secondary ChilledWater Return

Magna3

MV

Plate HX

Plate HX

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Primary-Secondary-Tertiary

Piping Tips• When HX are used, additional tanks and air separator devices must be added to tertiary

• Controls for secondary and tertiary systems are independent

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Primary-Secondary-Tertiary

Advantages• Hydraulic isolation• Thermal isolation• Horsepower reduction• Operational cost savings• System performance optimization

Disadvantages• Additional piping• Additional control valves• First cost• Over-pressurization of near zones unless plate hx is used

• More pumps

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Open Piped Systems

Chiller Piping• Condenser water piping• Condenser water with economizer.

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Condenser Water Piping

Return

Supply

Tower

Evaporator

Condenser

Primary Pump(s)

Secondary Pump(s)

CondenserPump(s)

ChillerSedimentSeparator

Expansion TankAnd Air Separator

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Condenser Water w/ Economizer

Return

Supply

Tower

Evaporator

Condenser

Primary Pump(s)

Secondary Pump(s)

CondenserPump(s)

Head PressureControl Valve

Heat Exchanger

Loads

Sediment Separator

Expansion TankAnd Air Separator

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Condenser Water Piping

Condenser Water Tips• Installation

• Keep pump suction flooded• Watch NPSH

• Operation• Air pockets• End of curve

• Maintenance• Strainers• Air vents

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Best Practice Design

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Best Practice Design

• Why• Constant speed pump• Variable speed pump

Optimize Pump Impeller

Best Practice Design

• Why‒ Equipment over-sizing‒ Cost penalty‒ Mandate

Optimize Pump Impeller

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Best Practice DesignConstant speed pump

• Trim the impeller.• Utilize the affinity laws.• Follow the system curve.• Save operating cost.• First costs.

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Variable speed pump• Impeller optimization• Follows affinity laws• Does not correct for poor engineering• Over-sized pumps minimize turndown ratio• Over-sized pumps and motors operate at lower efficiencies

• No added first costs

Best Practice Design

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Primary Piping for Hot Water Systems• Pump out of a boiler• Keep the boiler at the lowest possible pressure

• Remember NPSH!Bo

iler

2

P1P2Bo

iler

1

Best Practice Design

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Primary Piping for Chilled Water Systems• Pump into a chiller• Largest pressure drops after the pump

Chill

er

Primary Pumps

Chill

er

Chill

er

Best Practice Design

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System Bypass Options

Return

Supply

PumpController

Secondary CS Pump(s)

Common Pipe

Chille

r 2

Chille

r 1

Chille

r 3

Best Practice Design

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System Bypass Options• Locate bypass near end of system• Locate bypass near end of major loops• Selectively leave 3-way valves• Bypass with pressure activated control• Variable speed considerations

Best Practice Design

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Effect at minimum VFD speed• Below 30% speed: CS, but still VV

1201101009080

504030

2010

7060

0 10 20 30 40 50 60 70 80 90 1000 % Flow

Hea

d

100 % Speed

30% Speed

Best Practice Design

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1000 GPM

1000 GPMPump 1Variable Speed:500GPM@ 100 Ft

Pump 2ConstantSpeed:500 GPM@ 100 Ft

Wrong!

Mixing CS and VS PumpsBest Practice Design

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Sensor Location

Return

Supply

PumpController

VFDs

∆PSensor

Chille

r 3

Chille

r 2

Chille

r 1

Primary Pumps

Secondary Pumps

Best Practice Design

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Sensor Location

• The Traditional Way– Hydronically, the farthest load– Typically the largest, farthest load– Maximize the variable head loss– Multiple sensors are a benefit

Best Practice Design

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Optimized solution not only for the pumps, but for the total system conditions

• Uncontrolled (constant volume) curve• Constant pressure• Proportional pressure• Temperature control• FLOWADAPT• AUTOADAPT

Best Practice Design

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Best Practice Design

Q100%25%

H

1. Uncontrolled2. Constant pressure3. Proportional pressure (calculated)4. Proportional pressure (measured)5. Temperature control

0 20 40 60 80 100

100

80

60

40

20

0

Flow in %

Effec

t in

% 1.

2.

3.4.5.

Get Additional Energy Savings

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35

40

45

50

55

60

65

70

100%75%50%25%0%Flow in %

Efficie

ncy %

Constant P. Proportional P. Proportional P. Temperature Control

Best Practice Design - Demand MoreTotal Efficiency vs. Control Modes

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Total efficiency

30

40

50

60

70

100%75%50%25%0%Flow

Constant PressureProportional PressureProportional PressureTemperature Control

EFFECT P1

020406080100

100%75%50%25%0%Flow

Constant PressureProportional PressureProportional PressureTemperature Control

Best Practice Design - Demand More Comparison

Flow Limit

0 25 50 75 100

FLOWLIMITPotential saving compared to anunintelligent pump

Potential saving compared with proportional pressure mode

Duty point

Additional saving with FLOWLIMIT

Performance curve

Intelligent Control – FLOWADAPT/FLOWLIMIT

Best Practice Design - Demand More

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Best Practice Design - Demand More