seminar 5 free cooling for water source heat pump systems v2 · 2017-01-03 · 60°f ewt 12 gpm...

1

Brian MeneghanSpecifying EngineeringCarrier Corporation

© Carrier Corporation 20157/10/15 / SEM005 Ver. 1.1

In order to receive a certificate and professional development hoursfor this symposium you must:

1. Sign the symposium attendance sheet, which demonstrates that youhave attended the symposium.

This will be passed around the room at the start of the symposium.

Certificates cannot be issued without your signature on this sheet.Print legibly so that information can be easily verified.

2. During the symposium, demonstrate participation by answering theassessment questions. These are self-graded.

3. Complete the EvaluationAt the end of the symposium, you must also complete the evaluation.

4. If you are a P.E. in New York, North Carolina, or Florida, sign theappropriate sheet with your P.E. number for that state.If your P.E. is in North Carolina, fill out the additional NC evaluation form.

Turn in the Evaluation to the moderator.Certificates will be delivered to you after the symposium.

PROFESSIONAL DEVELOPMENT CREDITS

2

OBJECTIVES

At the end of this seminar you should be able to:

1. Select from a list of options the types of WSHPsystems

2. Identify the difference in integrated and non-integrated economizers

3. Select the benefits of waterside economizers forenergy savings

4. Select the application conditions for whenwaterside economizer should be used

5. Identify for a given climate zone if watersideeconomizer is required

3

AGENDA

4

• Water Source Heat Pump (WSHP) SystemOverview

• WSHP Waterside Economizer Overview

• WSHP Waterside Economizer DesignConsiderations

• ASHRAE 90.1 and Waterside Economizers

• Summary

INTRODUCTION TO WSHP

6

Water Source Heat Pump OverviewWater to Air Heat Pump: packaged air to water unit that provides bothheating and cooling of air by absorbing heat from or rejecting heat to awater loop.


7

Water Source Heat Pump Overview

Cooling Mode Heating ModeHeat Absorbed from Supply Air

Heat from Air Rejected to Condenser LoopCompressor Heat Rejected to Condenser Loop

Heat Absorbed from Condenser LoopHeat from Loop Rejected to Supply Air

Compressor Heat Rejected to Supply Air


8

Water Source Loop Overview

Adds Heat

Adds HeatRemoves

Heat

Removes Heat

Ideal System: Heat Added = Heat Removed

Sometimes Heat Added > Heat Removed

Sometimes Heat Added < Heat Removed

Photo Source: Carrier HAP v4.9


9

Water Loop Heat Adders and Rejecters

Photo Source: FHP Manufacturing

Boiler and Fluid Cooler

• Boiler adds heat, Fluid Cooler reject heat

• 68°F - 86°F typical loop temperature(Standard Range)

Geothermal

• Ground absorbs or adds heat to loop

• Ground or Lake/Pond Loop (Closed Loop)

• Ground Water Loop (Open Loop)

• Hybrid with Boiler or Tower

Hybrid System (Geo and Tower)


10

Boiler and Tower Loop Overview


Rejects Heat from Loop

Adds Heat to Loop

Typical Loop Temp:Heating: 68°FCooling: 86°F

When Heat Added > Heat Removed

When Heat Removed > Heat Added

Standard Range Loop


11

Typical Geothermal Loop (Ground Loop)


Absorbs Heat from Loop

Adds Heat to Loop



Typical Loop Temp:Depends on

Location

Extended Range Loop

QUESTION #1

12

A Water Source Heat Pump provides heating by:

A. Absorbing heat from a water loop and rejecting it to thesupply air stream

B. Absorbing heat from the supply air stream andrejecting it to the water loop

C. Hot gas reheat

D. None of the above


13

Warm Weather Loop Overview


Cooling Loop Temperature:

*Cooling Loop Temperature:

86ºF

* Loop temperature depends on location

Heat Added > Heat removed


14

Cold Weather Loop OverviewHeating Loop Temperature:

*Heating Loop Temperature:

68ºF

Heat Removed > or ≤ Heat RemovedPhoto Source: FHP Manufacturing* Loop temperature depends on location


15

Cold Weather Loop: Cooling Dominant Building


Heat Added ≥ Heat Removed(Cooling Load > Heating Load)


16

Cold Weather Loop: Cooling Dominant Building


Cooling Load Exceeds or Equals Heating Load• Typically core vs. perimeter zones• Specialty (high load) cooling load areas

Heating Systems to Absorb from Loop• Perimeter zones during cold months• WSHP DOAS unit during cold months (if equipped)

Water Cooled System and Cool Environment• Heat is easily rejected to environment• Cold air can absorb heat and some moisture• Cool earth can absorb heat


17

Cold Weather Loop


Maintain Low Loop Temperature40°F-60°F

WSHP WATERSIDE ECONOMIZER

19

What is a Waterside Economizer?

• Economizer, water or waterside: asystem by which the supply air of acooling system is cooled indirectly withwater that is itself cooled by heat ormass transfer to the environmentwithout the use of mechanical cooling.

• -ASHRAE 90.1-2013

Source: ASHRAE Standard 90.1-2013


20

Waterside Economizer Types

Chiller Bypass Supply Air Precooling

Water Precooling

Water to Water Systems Water to Air Systems

Source: ASHRAE 90.1 Users Guide


21

WSHP Waterside Economizer Overview

Photo Source: Carrier Corporation

WSHP with Supply Air Precooling Economizer Package:

• An air to water coil, mounted upstream of the DX coil

• A water control valve and piping, to direct water to the economizer coil

• An aquastat or other water control device to control the water valve

• Condensate drain pan

Economizer Coil

Control Valve

Aquastat & ValveActuator

Airflow Extended Range Kit(Insulated externaland internal piping)

Economizer WaterPiping


22

WSHP Waterside Economizer Operation• When possible, the environment is

allowed to absorb enough heat toproduce cold loop water

• When the loop temperature is lowenough, the chilled loop water isdirected to the economizer coil

• The cold loop water passing through thecoil and absorbs heat from air passingthrough the coil

• Reduces or eliminates the mechanicalcooling load, providing a “free” cooling Water Cooled System with Supply

Air Precooling Economizer

Source: ASHRAE 90.1 Users Guide

QUESTION #2

23

Which type of Waterside Economizer is typically used inWater Source Heat Pump systems?

A. Chiller bypass

B. Supply air pre-cooling

C. Water pre-cooling

D. Fan cycling


24

Waterside Economizer Capacity

Waterside Economizer Coil Capacity• Coils typically sized to provide 90% capacity at 45°F EWT

• Entering water temperature greatly impacts capacity

• Integrated economizers allow for higher water temps to be utilized

Economizer Airside Pressure Drop• Constant airside pressure drop

• Adds to fan energy consumption

Economizer Waterside Pressure Drop• Variable waterside pressure drop



25


Numbers based on the average of three industries manufacturers

Unit Size 1 Ton 2 Ton 3 Ton 4 Ton 5 Ton

Avg. Capacity (Tons) 0.99 1.98 2.65 4.08 4.79


Avg. P.D. (in. wg.) 0.11 0.15 0.16 0.18 0.24


Avg. P.D. (ft. wt.) 0.99 3.09 4.65 4.21 5.06

Average Economizer Waterside Pressure Drop

Average Economizer Airside Pressure Drop

Average Economizer Capacity

All data based on 80°F/67°F entering coil air temperature at 400 CFM/tonand 45°F entering water temperature at 3 GPM/ton


26


Source: Carrier Corporation 50PC Performance Data

2To

nU

nit

Entering WaterTemperature (°F)

Total CoolingCapacity (MBH)

% of NominalCapacity

40 26.6 114%

45 22.1 94%

50 17.5 75%

60 10.8 46%

4To

nU

nit




40 52.9 110%

45 43.2 90%

50 34.1 71%

60 20.16 42%

All data based on: 400 CFM/Ton airflow, 80.6°F/66.2°F entering coilair temperature and 3 GPM/Ton condenser water flow.

90+% of nominal capacity at 45°F EWT 40%+ Capacity with 60°F Water


27

WSHP Waterside Economizer TypesIntegrated Economizer

• Allows mechanical cooling wheneconomizer is enabled, economizeracts as a cooling stage

• Economizer piped in series withcondenser

• Multi-stage control

Non-Integrated Economizer

• Mechanical cooling isdisabled when economizer isenabled

• Economizer may be piped inseries or parallel

• Single stage control



28


Source: Carrier Corporation 50PC Performance Data

2To

nU

nit




40 26.6 114%

45 22.1 94%

50 17.5 75%

60 10.8 46%

4To

nU

nit




40 52.9 110%

45 43.2 90%

50 34.1 71%

60 20.16 42%

All data based on: 400 CFM/Ton airflow, 80.6°F/66.2°F entering coilair temperature and 3 GPM/Ton condenser water flow.

No

n-

Inte

gra

ted

Inte

gra

ted

Inte

gra

ted

No

n-

Inte

gra

ted

DESIGN CONSIDERATIONS

29

Waterside Economizer Example

Non-Integrated EconomizerIntegrated Economizer

ExampleNominal 4 Ton Unit, Standard Efficiency

1400 CFM, 0.4” ESP, PSC Fan80°F/67°F EAT

60°F EWT12 GPM

Economizer Capacity: 16.4 MBHEconomizer LAT: 69.6°F/63.2°F

Mechanical Cooling Capacity: 50.4 MBHMechanical Cooling LAT: 49.1°F/48.1°F

Total Capable Capacity: 66.8 MBH

Example:Nominal 4 Ton Unit, Standard Efficiency

1400 CFM, 0.4” ESP, PSC Fan80°F/67°F EAT

60°F EWT12 GPM

Economizer Capacity: 16.4 MBHEconomizer LAT: 69.6°F/63.2°F

Mechanical Cooling Capacity: 0 MBHMechanical Cooling LAT: 69.6°F/63.2°F

Total Capable Capacity: 16.4 MBH

Source: Carrier Corporation 50PC Performance Data 50PC-09PD


30

WSHP Economizer Waterflow Diagram

Economizer Disabled

Shut Off Solenoid (Optional)Temperature Bulb

WatersideEconomizer Coil(Water to Air)

Loop Water In

Aquastat

3 WayMotorized

Control Valve

Condenser Coil(Refrigerant to

Water)

Loop Water Out

45°

50°F


31

WSHP Economizer Waterflow Diagram

Economizer Enabled

45°

Shut Off Solenoid (Optional)Temperature Bulb

WatersideEconomizer Coil(Water to Air)

Loop Water In

Aquastat

3 WayMotorized

Control Valve

Condenser Coil(Refrigerant to

Water)

Loop Water Out

45°F


32

Waterside Economizer Airflow Diagram

Loop Water In

Loop Water Out

Loop Water In

Loop Water Out

Loop Water In

Loop Water Out

Mechanical Cooling Mode

(Economizer Disabled)

Economizer Only Mode(Integrated or Non-

Integrated)

Economizer andMechanical Cooling

(Integrated Only)

Airflow Airflow Airflow

QUESTION #3

33

An Integrated Economizer allows for the simultaneousoperation of the following:

A. Economizer and mechanical cooling

B. Economizer and exhaust fan

C. Mechanical cooling and heating

D. Mechanical cooling and exhaust fan


34

Waterside Economizer System Example


ExampleBuilding CoreGeothermal Loop(6) 2 Ton WSHPsECM Fan Motors800 CFM Each6 GPM Each45°F Loop Temperature

Fan Hours: 500Cooling Hours: 500Pump Hours: 1000

Compare systems with WSEand without WSE

1 2

3 4

5 6


35

Example System without Waterside Economizer

System Performance withoutWaterside Economizer

Zone Fan Energy(kWh)

Compressor(kWh)

1 100 337

2 100 337

3 100 337

4 100 337

5 100 337

6 100 337

Total: 600 2022

Unit AirsidePressure Drop

Unit WatersidePressure Drop

Pump Energy(kWh)

0.4 8.4 117555°F45°F

5 6

3 4

1 2



36

Example System with Waterside Economizer

System Performance withWaterside Economizer

Zone Fan Energy(kWh)

Compressor(kWh)

1 120 0

2 120 0

3 120 0

4 120 0

5 120 0

6 120 0

Total: 720 0

Unit AirsidePressure Drop

Unit WatersidePressure Drop

Pump Energy(kWh)

0.6” 12.6 ft. 125052°F45°F

1 2

3 4

5 6



37

Waterside Economizer Benefits

Cost Savings• Energy savings from reduced mechanical cooling load

• Energy savings from reduced heat rejection system range

• Eliminate head pressure control (extended range systems)

• Potential to extended mechanical equipment life

Code Compliance• Local codes requirements

• ASHRAE 90.1

• LEED ® (energy efficiency)

Photo Source: Green IT LEED® is a registered trademark of the U.S. Green Building Council ®.

QUESTION #4

38

What is the main benefit of using Waterside Economizerson WSHP systems?

A. Energy savings

B. Reduced fan energy usage

C. Reduced waterside pressure drop

D. Reduced airside pressure drop


39

Waterside Economizer Impacts

Increased Airside Pressure Drop

• Waterside economizer adds to pressure drop at all times

• Increased ESP means higher fan energy consumption

• Supply fan may need to be upsized

Increased Waterside Pressure Drop

• Waterside economizer coil adds to waterside pressure drop,when active

• When inactive, the WSE controls also add to watersidepressure drop

• Increased waterside pressure means higher pump energyconsumption

• Pumps may need to be upsized


40

Waterside Economizer System Impacts


Potential Increase in System Heating Energy Consumption• Low loop temperature decreases WSHP heating capacity

• Unit may need to be upsized or add ancillary heating

• Heat of compressor is not added to loop from mechanical cooling

Potential Increase in Water Usage• Evaporation from Evaporative Fluid Cooler

• Minimized by using Dry Cooler when possible


41

Economizer Comparison (on WSHP System)

Airside Economizer

IAQ Negative• Can introduce poor quality air into the

space

• Will reduce indoor RH levels during lowambient conditions

High Cost Impact• High installation cost (not typically

available factory installed on WSHP units)

• High installation cost

• Complex control equipment

Waterside Economizer

IAQ Neutral• Does not introduce poor quality air

into the space

• Does not reduce indoor RH levelsduring low ambient conditions

Low Cost Impact• Typically low/medium cost (when

factory installed)

• Minimal additional installation cost

• Simple control equipment

Ideal Application: Waterside Economizer Energy Savings isGreater than Energy Increase• Must be able to take advantage of economizer

• Airside and waterside energy increase

• Heating energy increase (if any)

Water Loop Low Temperature Capability

Waterside Economizer Operating Hours

Minimize System Impact• Airside, waterside, and heating

APPLICATION CONSIDERATIONS

43Photo Source: dreamstime.com

Waterside Economizer Application

44

Water Loop Low Temperature Capability



Ideal Waterside Economizer Loop Temperature• 50 - 100% of nominal capacity

• Integrated economizer: 40-60°F

• Non-integrated economizer 40-45°F

Geothermal Systems• Location solar load determines loop temperature capability

• Local factors and loop sizing impact loop temperature

Fluid Cooler Systems• Evaporative fluid cooler (cooling towers) or dry coolers

• Local climate determines loop temperature capability

45

Geothermal Water Loop Temperature

Photo Source: Don Penn Consulting, 2002

Zones 1-3Low Loop Temperatures

Rare


Some of the Year


Most of the Year


7

6

5

3

4

2

1

46

Fluid Coolers Overview

Photo Carrier Corporation


Dry Cooler (Fluid Cooler)

• Heat Transfer• Loop temperature depends on

ambient dry bulb temperatureand selected dry-cooler range

• No evaporation = no water loss

Evaporative Cooling Tower

• Mass & Heat Transfer• Loop temperature depends on

ambient wet bulb temperatureand selected tower approach

• Low loop temperature approachmay differ from design approach

• Evaporation = water loop loss

47

Fluid Cooler Loop Temperature Capability

Photo Source: US Department of Energy


Zones 1-2Loop Temperature Too

High for WatersideEconomizer

Zones 3-5Acceptable Loop

Temperature For WSE withCooling Tower

Zones 6-7Ideal Loop Temperature forWSE with Cooling Tower or

Dry Cooler

Assumes appropriately sized equipment forapplication range and approach

48

Low Loop Temperature HoursRecommend 20%+ Annual Hours at Low Loop Temperatures

• Offset airside & waterside pressure drop

• Offset heating energy increase for standard range (boiler & tower)

• Achievable in Mild and Cold Climates

• Dependent on loop type, heat rejecter type, and economizer type



49

Sample Economizer Operating Hours

Photo Source: US Department of Energy

Chicago, IL

Charlotte, NC

Miami, FL

Typical Annual Operating Hours: 4000



Rare


Some of the Year


Most of the Year

GrandRapids

50

Potential Waterside Economizer Hours (Chicago, IL)

Good application for Waterside Economizer with Cooling Tower or Dry Cooler

Loop Temp < 45°F: 1274 Hours (32%)


Dry Cooler (10°F Range)



Cooling Tower (7°F Approach)

0

50

100

150

200

250

300

350

400

-7°F

-2°F

2°F

7°F

12

°F

17

°F

22

°F

27

°F

32

°F

37

°F

42

°F

47

°F

52

°F

57

°F

62

°F

67

°F

72

°F

77

°F

82

°F

87

°F

92

°F

Dry Bulb Bin Hours

0

50

100

150

200

250

300

350

400

-8°F

-0°F

0°F

5°F

10

°F

14

°F

19

°F

24

°F

29

°F

33

°F

37

°F

42

°F

45

°F

50

°F

53

°F

59

°F

61

°F

66

°F

69

°F

71

°F

74

°F

Wet Bulb Bin Hours45°F 60°F

45°F 60°F



Geothermal


51

Potential Waterside Economizer Hrs. (Charlotte, NC)

Good application for Waterside Economizer with Cooling Tower









Geothermal0

100

200

300

400

500

600

Dry Bulb Bin Hours

45°F 60°F

0

100

200

300

400

500

600

Wet Bulb Bin Hours

45°F 60°F


52

Potential Waterside Economizer Hours (Miami, FL)

Poor application for Waterside Economizer


Loop Temp < 60°F: 160 Hours (3.4%)

Dry Cooler Performance


Loop Temp < 60°F: 136 Hours (3.4%)

Cooling Tower Performance



Geothermal Performance0

200

400

600

800

1000

1200

1400

47°F 52°F 57°F 62°F 67°F 72°F 77°F 82°F 87°F 92°F

Dry Bulb Bin Hours

45°F 60°F

0

200

400

600

800

1000

1200

1400

43°F 47°F 51°F 56°F 61°F 65°F 70°F 73°F 76°F 77°F

Wet Bulb Bin Hours

45°F 60°F


0

100

200

300

400

500

Wet Bulb Bin Hours

0

100

200

300

400

500

Dry Bulb Bin Hours

Good application for Waterside Economizer with Cooling Tower, Dry Cooler, or Geothermal

45°F 60°F

45°F 60°F









Geothermal


Potential Waterside Economizer Hours (Grand Rapids)

54

Potential Economizer Operating Hours (Variable)


Slide data depends on presentation location

Loop Temp < 45°F: Hours (0%)

Loop Temp < 60°F: Hours (0.04%)

Dry Cooler Performance



Cooling Tower Performance



Geothermal Performance0

200

400

600

800

1000

1200

1400

47°F 52°F 57°F 62°F 67°F 72°F 77°F 82°F 87°F 92°F

Dry Bulb Bin Hours

45°F 60°F

0

200

400

600

800

1000

1200

1400

43°F 47°F 51°F 56°F 61°F 65°F 70°F 73°F 76°F 77°F

Wet Bulb Bin Hours

45°F 60°F

55

Waterside Economizer Operating Hours



Waterside Economizer Is Only Effective if it Can Be Used• Requires cooling load during cool periods

• More economizer operating hours provide greater savings

Depends on Building Load Profile• Core vs. perimeter zoning

• Specialty areas

Depends on Economizer Type• Integrated Economizer allows for wider water temperature range

56

Building Load Profile



Ideal Waterside Economizer Applications are Cooling Dominant(standard range systems)

• During cool months, cooling load ≥ the building heating load

• Depends on building usage and zone layouts (core vs. perimeter)

• Minimized impact of heating efficiency decrease for standard range systems

Cooling DominantBuilding

Heating DominantBuilding

Cooling(Core Zones)

Perimeter Zones

Heating

Heating(Perimeter Zones)

Cooling (Core Zones)

57

Building Load Profile


Cooling Dominant Building (Cooling > Heating)

• High operating hours for Waterside Economizer

• Good application for WSE (cooling savings > heating increase)

Standard Range Heating Dominant Building

• WSHP heating efficiency decreases at low loop temperatures

• Poor application for WSE (heating increase > cooling savings)

Extended Range Heating Dominant Building

• WSE may still be beneficial (if cooling savings > heating increase)

58

Minimize Economizer System Impact



Airside Pressure Drop

• Waterside Economizer coil mounted on unit returnadds to constant fan pressure

Waterside Pressure Drop

• When active, Waterside Economizer coil adds to thepump head pressure

Heating Impact

• Low loop temperatures may impact WSHP heatingperformance

59

Airside and Waterside Pressure Drop

Minimize Airside Pressure Drop• Use high efficiency fan motors (ECM)

• Use variable speed fan speed control

• Use intermittent fan operation

• If the unit rarely enters cooling mode duringlow ambient conditions, don’t use a WSE

Minimize Waterside Pressure Drop• Use high efficiency pump motors

• Use variable speed pumps



60

Heating System Impact



Waterside Economizer Requires Low Loop Temperature• WSE effectiveness reduced at loop temperatures above 60°F

WSHP Heating Efficiency Drops at Low Loop Temperatures• May require upsizing units or experience longer run times

• Minimal/no impact on Extended Range (Geothermal) systems

• Impacts Standard Range (Boiler & Tower) systems

• Reduced boiler load reduces boiler energy consumption

61



Data Source: Carrier WSHP Builder v6.0 All data based on: 2 ton base unit, 400 CFM/Tonairflow, 68°F entering coil air temperature and 3 GPM/Ton condenser water flow.

82°F

84°F

86°F

88°F

90°F

92°F

94°F

96°F

98°F

100°F

102°F

3

3.2

3.4

3.6

3.8

4

4.2

4.4

4.6

40°F 42°F 44°F 46°F 48°F 50°F 52°F 54°F 56°F 58°F 60°F 62°F 64°F 66°F 68°F

Su

pp

lyA

irT

em

pera

ture

CO

P

Entering Water Temperature

Entering Water Temperature vs. Supply Air Temperature

COP LAT

3.7 COP92°F SAT

4.2 COP98°F SAT

4.5 COP101°F SAT

StandardRange Heating

Loop Temp

GeothermalHeating Loop

Temp

62



Data Source: Carrier WSHP Builder v6.0 All data based on: 2 ton base unit, 400 CFM/Tonairflow, 68°F entering coil air temperature and 3 GPM/Ton condenser water flow.

°F

1°F

2°F

3°F

4°F

5°F

6°F

7°F

8°F

5,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

40°F 45°F 50°F 55°F 60°F 65°F 70°F

WS

HP

Wate

rTem

pera

ture

Dro

p

Bo

iler

Lo

ad

per

WS

HP

To

n(B

TU

)

Water Loop Temperature

Effect of Water Loop Temperature on Boiler Load

Boiler Load WSHP ΔT

11,100 BTU7.4°F ΔT

7,800 BTU5.2°F ΔT

9,750 BTU6.5°F ΔT

63

Waterside Economizer System Example


ExampleOffice Building(10) 2 Ton WSHPsBoiler & Tower68°F Loop Temp (No WSE)45°F Loop Temp (No WSE)ECM Fan Motors800 CFM Each6 GPM EachElectric Boiler

Fan Hours: 500Cooling Hours: 500 (Core)Heating Hours 500 (Perimeter)

Compare systems with WSEand without WSE


1 2

3 4

5 6

7

810

9

64

WSHP System without Waterside Economizer


System Performance withoutWaterside Economizer

Zone Energy Consumption (kWh)

1 570

2 570

3 570

4 570

5 570

6 570

7 638

8 638

9 638

10 638

Tower 305

Boiler 0

Pump 1950

Total: 8227 kWh

71°F68°F

8

5 6

3 4

1 2

7

10

9

10


65

WSHP System with Waterside Economizer


System Performance withWaterside Economizer


1 120

2 120

3 120

4 120

5 120

6 120

7 788

8 788

9 788

10 788

Tower 275

Boiler 0

Pump 2000

Total: 6145 kWh

1 2

3 4

5 6

7

810

9

47°F45°F


66

Energy Consumption


No Waterside Economizer


1 570

2 570

3 570

4 570

5 570

6 570

7 638

8 638

9 638

10 638

Tower 305

Boiler 0

Pump 1950

Total: 8227 kWh

With Waterside Economizer


1 120

2 120

3 120

4 120

5 120

6 120

7 788

8 788

9 788

10 788

Tower 275

Boiler 0

Pump 2000

Total: 6145 kWh

HVAC Energy Savings: 25.3%


67

Summary


When Should a Waterside Economizer be Used?

• If code requires economizer use

• Great fit for Geothermal (Extended Range) Systems (loop temps low by design)

• Good fit for standard range, but location dependent and may need to lower heating loop temps

• Constant cooling load in cold months (e.g. core cooling load)

• >20% low loop temp hours

• If Cooling Energy Savings > Airside + Waterside + Heating energy increase

Energy Savings Factors:

• Geographic Location

• Building Load Profile

• Heating System Impact

• Economizer Type

• Airside & Waterside Pressure Drop


QUESTION #5

68

Which of the following should be considered whenapplying Waterside Economizers to WSHP?

A. Condenser loop temperature range capability

B. Local climate/ambient temperature

C. Heating system impact

D. All of the above

ASHRAE 90.1 ENERGY STANDARD

70

Overview

Source: ASHRAE Standard 90.1-2013 Purchased stock graphics BLDCM022 by permission

ASHRAE 90.1 is a standard that provides minimum guidelines for buildingenergy efficiency design for buildings (except low rise).

ASHRAE 90.1 ENERGY STANDARD

71

Waterside Economizers

Source: ASHRAE Standard 90.1-2013

Waterside Economizers are in Prescriptive Path• WSE with WSHP systems are not required on certain systems

• WSE with WSHP may not meet some requirements of 90.1 (heatingimpact)

Waterside Economizer Beneficial to Energy Cost Method

ASHRAE 90.1 AND WSE

72

Prescriptive Path

Derived from: ASHRAE 90.1

Required Based on Climate Zone• Not required in Zone 1

Required Based on Unit Size• Not required on systems under 4.5 tons

WSE Requirement Can Be Waived• Increase unit efficiency based on

Climate Zone

• Zone operating hours

(less than 20 hours/Week)

ClimateZone

EfficiencyImprovement

2a 17%

2b 21%

3a 27%

3b 32%

3c 65%

4a 42%

4b 49%

4c 64%

5a 49%

5b 59%

5c 74%

6a 56%

6b 65%

7 72%

8 77%

ASHRAE 90.1 AND WSE

73

Waterside Economizer Requirements

Minimum Capacity Requirements (6.5.1.2.1)• Provide 100% design capacity at 50°F/45°F ambient

Coil Waterside Pressure Drop Limited to 15 Ft. (6.5.1.2.3)• Limit pressure drop during non-economizer operation, if exceeded

Must be an Integrated Economizer (6.5.1.2.3)• Allow mechanical cooling with economizer operation

ASHRAE 90.1 AND WSE

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Waterside Economizer Requirements

Economizer Must Not Increase Heating Energy Use (6.5.1.2.4)HVAC system design and economizer controls shall be such that

economizer operation does not increase the building heating

energy use during normal operation.

Heating Energy Consumption = Boiler Energy + Heat Pump Heating Energy

Source: Interpretation IC 90.1-2010-15 of ANSI/ASHRAE/IES Standard 90.1-2010

QUESTION #6

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In ASHRAE 90.1, which of the following impacts theWaterside Economizer prescriptive requirement?

A. Unit capacity

B. Geographic location

C. Unit operating hours

D. All of the above

SUMMARY

• Waterside Economizers can be a great fit forWater Source Heat Pump systems

• Waterside Economizers are a powerful tool forenergy savings, when properly applied

• The negative impacts of Waterside economizerscan easily be overcome with smart designchoices

• Energy savings and code compliance are drivingforces behind Waterside Economizer use

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WSHP Waterside Economizers

SUMMARY

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REMEMBER TO FILL OUT AND TURN IN THE EVALUATION FORM

Reminder: If you are registered in Florida, New York, or North Carolina,you must also sign the sheets in the back at the end of the session.

Please print your name, include your registration number, and sign the sheet.

seminar 5 free cooling for water source heat pump systems v2 · 2017-01-03 · 60°f ewt 12 gpm...

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