Brian Meneghan
Specifying Engineering
Carrier Corporation
© Carrier Corporation 2015
7/10/15 / SEM005 Ver. 1.1
1
PROFESSIONAL DEVELOPMENT CREDITS
In order to receive a certificate and professional development hours
for this symposium you must:
1. Sign the symposium attendance sheet, which demonstrates that you
have 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 the
assessment questions. These are self-graded.
3. Complete the Evaluation
At 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 the
appropriate 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.
2
OBJECTIVES
At the end of this seminar you should be able to:
1. Select from a list of options the types of WSHP
systems
2. Identify the difference in integrated and nonintegrated economizers
3. Select the benefits of waterside economizers for
energy savings
4. Select the application conditions for when
waterside economizer should be used
5. Identify for a given climate zone if waterside
economizer is required
3
AGENDA
• Water Source Heat Pump (WSHP) System
Overview
• WSHP Waterside Economizer Overview
• WSHP Waterside Economizer Design
Considerations
• ASHRAE 90.1 and Waterside Economizers
• Summary
4
INTRODUCTION TO WSHP
Water Source Heat Pump Overview
Water to Air Heat Pump: packaged air to water unit that provides both
heating and cooling of air by absorbing heat from or rejecting heat to a
water loop.
6
INTRODUCTION TO WSHP
Water Source Heat Pump Overview
Cooling Mode
Heating Mode
Heat Absorbed from Supply Air
Heat from Air Rejected to Condenser Loop
Compressor Heat Rejected to Condenser Loop
Heat Absorbed from Condenser Loop
Heat from Loop Rejected to Supply Air
Compressor Heat Rejected to Supply Air
7
INTRODUCTION TO WSHP
Water Source Loop Overview
Adds Heat
Removes Heat
Removes
Heat
Adds Heat
Ideal System: Heat Added = Heat Removed
Sometimes Heat Added > Heat Removed
Sometimes Heat Added < Heat Removed
8
Photo Source: Carrier HAP v4.9
INTRODUCTION TO WSHP
Water Loop Heat Adders and Rejecters
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)
9
Photo Source: FHP Manufacturing
INTRODUCTION TO WSHP
Boiler and Tower Loop Overview
When Heat Added > Heat Removed
Rejects Heat from Loop
Typical Loop Temp:
Heating: 68°F
Cooling: 86°F
Adds Heat to Loop
When Heat Removed > Heat Added
Standard Range Loop
Photo Source: Carrier HAP v4.9
10
INTRODUCTION TO WSHP
Typical Geothermal Loop (Ground Loop)
When Heat Added > Heat Removed
Absorbs Heat from Loop
Typical Loop Temp:
Depends on
Location
Adds Heat to Loop
When Heat Added > Heat Removed
Extended Range Loop
Photo Source: Carrier HAP v4.9
11
QUESTION #1
A Water Source Heat Pump provides heating by:
A. Absorbing heat from a water loop and rejecting it to the
supply air stream
B. Absorbing heat from the supply air stream and
rejecting it to the water loop
C. Hot gas reheat
D. None of the above
12
INTRODUCTION TO WSHP
Warm Weather Loop Overview
Cooling Loop Temperature:
86ºF
Cooling Loop Temperature:
*
Heat Added > Heat removed
* Loop temperature depends on location
Photo Source: FHP Manufacturing
13
INTRODUCTION TO WSHP
Cold Weather Loop Overview
Heating Loop Temperature:
68ºF
Heating Loop Temperature:
*
Heat Removed > or ≤ Heat Removed
* Loop temperature depends on location
Photo Source: FHP Manufacturing
14
INTRODUCTION TO WSHP
Cold Weather Loop: Cooling Dominant Building
Heat Added ≥ Heat Removed
(Cooling Load > Heating Load)
15
Photo Source: FHP Manufacturing
INTRODUCTION TO WSHP
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
16
Photo Source: FHP Manufacturing
INTRODUCTION TO WSHP
Cold Weather Loop
Maintain Low Loop Temperature
40°F-60°F
17
Photo Source: FHP Manufacturing
WSHP WATERSIDE ECONOMIZER
What is a Waterside Economizer?
• Economizer, water or waterside: a
system by which the supply air of a
cooling system is cooled indirectly with
water that is itself cooled by heat or
mass transfer to the environment
without the use of mechanical cooling.
• -ASHRAE 90.1-2013
19
Source: ASHRAE Standard 90.1-2013
WSHP WATERSIDE ECONOMIZER
Waterside Economizer Types
Water to Water Systems
Water to Air Systems
Chiller Bypass
Supply Air Precooling
Water Precooling
20
Source: ASHRAE 90.1 Users Guide
WSHP WATERSIDE ECONOMIZER
WSHP Waterside Economizer Overview
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
Extended Range Kit
(Insulated external
and internal piping)
Airflow
Aquastat & Valve
Actuator
Control Valve
Economizer Water
Piping
21
Photo Source: Carrier Corporation
WSHP WATERSIDE ECONOMIZER
WSHP Waterside Economizer Operation
• When possible, the environment is
allowed to absorb enough heat to
produce cold loop water
• When the loop temperature is low
enough, the chilled loop water is
directed to the economizer coil
• The cold loop water passing through the
coil and absorbs heat from air passing
through the coil
• Reduces or eliminates the mechanical
cooling load, providing a “free” cooling
Water Cooled System with Supply
Air Precooling Economizer
22
Source: ASHRAE 90.1 Users Guide
QUESTION #2
Which type of Waterside Economizer is typically used in
Water Source Heat Pump systems?
A. Chiller bypass
B. Supply air pre-cooling
C. Water pre-cooling
D. Fan cycling
23
WSHP WATERSIDE ECONOMIZER
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
24
Photo Source: Carrier Corporation
WSHP WATERSIDE ECONOMIZER
Waterside Economizer Capacity
Average Economizer Capacity
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
Average Economizer Airside Pressure Drop
Unit Size
1 Ton
2 Ton
3 Ton
4 Ton
5 Ton
Avg. P.D. (in. wg.)
0.11
0.15
0.16
0.18
0.24
Average Economizer Waterside Pressure Drop
Unit Size
1 Ton
2 Ton
3 Ton
4 Ton
5 Ton
Avg. P.D. (ft. wt.)
0.99
3.09
4.65
4.21
5.06
All data based on 80°F/67°F entering coil air temperature at 400 CFM/ton
and 45°F entering water temperature at 3 GPM/ton
Numbers based on the average of three industries manufacturers
25
WSHP WATERSIDE ECONOMIZER
2 Ton Unit
Waterside Economizer Capacity
Entering Water
Temperature (°F)
Total Cooling
Capacity (MBH)
% of Nominal
Capacity
40
26.6
114%
45
22.1
94%
50
17.5
75%
60
10.8
46%
4 Ton Unit
90+% of nominal capacity at 45°F EWT
40%+ Capacity with 60°F Water
Entering Water
Temperature (°F)
Total Cooling
Capacity (MBH)
% of Nominal
Capacity
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 coil
air temperature and 3 GPM/Ton condenser water flow.
Source: Carrier Corporation 50PC Performance Data
26
WSHP WATERSIDE ECONOMIZER
WSHP Waterside Economizer Types
Integrated Economizer
Non-Integrated Economizer
• Allows mechanical cooling when
economizer is enabled, economizer
acts as a cooling stage
• Mechanical cooling is
disabled when economizer is
enabled
• Economizer piped in series with
condenser
• Economizer may be piped in
series or parallel
• Multi-stage control
• Single stage control
27
Photo Source: Carrier Corporation
WSHP WATERSIDE ECONOMIZER
4 Ton Unit
40
26.6
114%
45
22.1
94%
50
17.5
75%
60
10.8
46%
Entering Water
Temperature (°F)
Total Cooling
Capacity (MBH)
% of Nominal
Capacity
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 coil
air temperature and 3 GPM/Ton condenser water flow.
Source: Carrier Corporation 50PC Performance Data
Integrated
% of Nominal
Capacity
Integrated
Total Cooling
Capacity (MBH)
NonIntegrated
Entering Water
Temperature (°F)
NonIntegrated
2 Ton Unit
Waterside Economizer Capacity
28
DESIGN CONSIDERATIONS
Waterside Economizer Example
Integrated Economizer
Non-Integrated Economizer
Example
Nominal 4 Ton Unit, Standard Efficiency
1400 CFM, 0.4” ESP, PSC Fan
80°F/67°F EAT
60°F EWT
12 GPM
Example:
Nominal 4 Ton Unit, Standard Efficiency
1400 CFM, 0.4” ESP, PSC Fan
80°F/67°F EAT
60°F EWT
12 GPM
Economizer Capacity: 16.4 MBH
Economizer LAT: 69.6°F/63.2°F
Economizer Capacity: 16.4 MBH
Economizer LAT: 69.6°F/63.2°F
Mechanical Cooling Capacity: 50.4 MBH
Mechanical Cooling LAT: 49.1°F/48.1°F
Mechanical Cooling Capacity: 0 MBH
Mechanical Cooling LAT: 69.6°F/63.2°F
Total Capable Capacity: 66.8 MBH
Total Capable Capacity: 16.4 MBH
29
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
WSHP WATERSIDE ECONOMIZER
WSHP Economizer Waterflow Diagram
Waterside
Economizer Coil
(Water to Air)
3 Way
Motorized
Control Valve
Aquastat
Condenser Coil
(Refrigerant to
Water)
45°
Temperature Bulb
Shut Off Solenoid (Optional)
50°F
Loop Water In
Loop Water Out
Economizer Disabled
30
WSHP WATERSIDE ECONOMIZER
WSHP Economizer Waterflow Diagram
Waterside
Economizer Coil
(Water to Air)
3 Way
Motorized
Control Valve
Aquastat
Condenser Coil
(Refrigerant to
Water)
45°
Temperature Bulb
Shut Off Solenoid (Optional)
45°F
Loop Water In
Loop Water Out
Economizer Enabled
31
WSHP WATERSIDE ECONOMIZER
Waterside Economizer Airflow Diagram
Airflow
Airflow
Airflow
Loop Water In
Loop Water In
Loop Water In
Loop Water Out
Loop Water Out
Loop Water Out
Mechanical Cooling Mode
(Economizer Disabled)
Economizer Only Mode
(Integrated or NonIntegrated)
Economizer and
Mechanical Cooling
(Integrated Only)
32
QUESTION #3
An Integrated Economizer allows for the simultaneous
operation of the following:
A. Economizer and mechanical cooling
B. Economizer and exhaust fan
C. Mechanical cooling and heating
D. Mechanical cooling and exhaust fan
33
WSHP WATERSIDE ECONOMIZER
Waterside Economizer System Example
1
2
3
4
5
6
Example
Building Core
Geothermal Loop
(6) 2 Ton WSHPs
ECM Fan Motors
800 CFM Each
6 GPM Each
45°F Loop Temperature
Fan Hours: 500
Cooling Hours: 500
Pump Hours: 1000
Compare systems with WSE
and without WSE
34
Photo Source: Carrier Corporation
WSHP WATERSIDE ECONOMIZER
Example System without Waterside Economizer
System Performance without
Waterside Economizer
1
2
3
4
5
45°F
6
55°F
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 Airside
Pressure Drop
Unit Waterside
Pressure Drop
Pump Energy
(kWh)
0.4
8.4
1175
35
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
WSHP WATERSIDE ECONOMIZER
Example System with Waterside Economizer
System Performance with
Waterside Economizer
1
2
3
4
5
45°F
6
52°F
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 Airside
Pressure Drop
Unit Waterside
Pressure Drop
Pump Energy
(kWh)
0.6”
12.6 ft.
1250
36
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
WSHP WATERSIDE ECONOMIZER
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)
37
Photo Source: Green IT
LEED®
is a registered trademark of the U.S. Green Building
Council ®.
QUESTION #4
What is the main benefit of using Waterside Economizers
on WSHP systems?
A. Energy savings
B. Reduced fan energy usage
C. Reduced waterside pressure drop
D. Reduced airside pressure drop
38
WSHP WATERSIDE ECONOMIZER
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 waterside
pressure drop
• Increased waterside pressure means higher pump energy
consumption
• Pumps may need to be upsized
39
WSHP WATERSIDE ECONOMIZER
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
40
Photo Source: FHP Manufacturing
WSHP WATERSIDE ECONOMIZER
Economizer Comparison (on WSHP System)
Waterside Economizer
Airside Economizer
IAQ Neutral
IAQ Negative
• Does not introduce poor quality air
into the space
• Can introduce poor quality air into the
space
• Does not reduce indoor RH levels
during low ambient conditions
• Will reduce indoor RH levels during low
ambient conditions
Low Cost Impact
High Cost Impact
• Typically low/medium cost (when
factory installed)
• High installation cost (not typically
available factory installed on WSHP units)
• Minimal additional installation cost
• High installation cost
• Simple control equipment
• Complex control equipment
41
APPLICATION CONSIDERATIONS
Waterside Economizer Application
Ideal Application: Waterside Economizer Energy Savings is
Greater 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
43
Photo Source: dreamstime.com
APPLICATION CONSIDERATIONS
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
44
Photo Source: FHP Manufacturing
APPLICATION CONSIDERATIONS
Geothermal Water Loop Temperature
7
6
Zones 6-7
Low Loop Temperatures
Most of the Year
5
4
Zones 4-5
Low Loop Temperatures
Some of the Year
3
2
1
Zones 1-3
Low Loop Temperatures
Rare
45
Photo Source: Don Penn Consulting, 2002
APPLICATION CONSIDERATIONS
Fluid Coolers Overview
Evaporative Cooling Tower
Dry Cooler (Fluid Cooler)
• Mass & Heat Transfer
• Loop temperature depends on
ambient wet bulb temperature
and selected tower approach
• Low loop temperature approach
may differ from design approach
• Evaporation = water loop loss
• Heat Transfer
• Loop temperature depends on
ambient dry bulb temperature
and selected dry-cooler range
• No evaporation = no water loss
46
Photo Carrier Corporation
APPLICATION CONSIDERATIONS
Fluid Cooler Loop Temperature Capability
Zones 6-7
Ideal Loop Temperature for
WSE with Cooling Tower or
Dry Cooler
Zones 3-5
Acceptable Loop
Temperature For WSE with
Cooling Tower
Zones 1-2
Loop Temperature Too
High for Waterside
Economizer
Assumes appropriately sized equipment for
application range and approach
47
Photo Source: US Department of Energy
APPLICATION CONSIDERATIONS
Low Loop Temperature Hours
Recommend 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
48
Photo Source: FHP Manufacturing
APPLICATION CONSIDERATIONS
Sample Economizer Operating Hours
Zones 6-7
Low Loop Temperatures
Most of the Year
Chicago, IL
Grand
Rapids
Charlotte, NC
Miami, FL
Zones 4-5
Low Loop Temperatures
Some of the Year
Zones 1-3
Low Loop Temperatures
Rare
Typical Annual Operating Hours: 4000
49
Photo Source: US Department of Energy
APPLICATION CONSIDERATIONS
Potential Waterside Economizer Hours (Chicago, IL)
Dry Bulb Bin Hours
Dry Cooler (10°F Range)
400
350
300
250
200
150
100
50
0
Loop Temp < 60°F: 1761 Hours (44%)
92°F
87°F
82°F
77°F
72°F
67°F
62°F
57°F
52°F
47°F
42°F
37°F
32°F
27°F
22°F
17°F
12°F
7°F
2°F
-2°F
-7°F
Loop Temp < 45°F: 1274 Hours (32%)
60°F
45°F
Geothermal
Loop Temp < 60°F: 4000 Hours (100%)
Wet Bulb Bin Hours
Loop Temp < 45°F: 2000 Hours (50%)
400
350
300
250
200
150
100
50
0
Cooling Tower (7°F Approach)
45°F
74°F
71°F
69°F
66°F
61°F
59°F
53°F
50°F
45°F
42°F
37°F
33°F
29°F
24°F
19°F
14°F
10°F
5°F
0°F
-0°F
-8°F
Loop Temp < 60°F: 2573 Hours (65%)
Loop Temp < 45°F: 1761 Hours (32%)
60°F
Good application for Waterside Economizer with Cooling Tower or Dry Cooler
50
APPLICATION CONSIDERATIONS
Potential Waterside Economizer Hrs. (Charlotte, NC)
Dry Bulb Bin Hours
600
500
Dry Cooler (10°F Range)
Loop Temp < 60°F: 983 Hours (24%)
400
Loop Temp < 45°F: 304 Hours (7%)
300
200
100
0
Geothermal
45°F
60°F
Wet Bulb Bin Hours
Loop Temp < 60°F: 2000 Hours (50%)
Loop Temp < 45°F: 500 Hours (25%)
600
500
400
300
Cooling Tower (7°F Approach)
200
100
Loop Temp < 60°F: 1737 Hours (43%)
0
Loop Temp < 45°F: 799 Hours (20%)
45°F
60°F
Good application for Waterside Economizer with Cooling Tower
51
APPLICATION CONSIDERATIONS
Potential Waterside Economizer Hours (Miami, FL)
Dry Bulb Bin Hours
Dry Cooler Performance
1400
1200
Loop Temp < 60°F: 160 Hours (3.4%)
1000
Loop Temp < 45°F: 0 Hours (0%)
800
600
400
200
0
47°F
52°F
57°F 62°F
67°F
72°F 77°F
82°F
87°F
92°F
45°F 60°F
Geothermal Performance
Loop Temp < 60°F: 0 Hours (0%)
Wet Bulb Bin Hours
Loop Temp < 45°F: 0 Hours (0%)
1400
1200
1000
800
Cooling Tower Performance
600
400
Loop Temp < 60°F: 136 Hours (3.4%)
200
0
43°F
45°F
47°F 51°F
56°F
61°F
65°F 70°F
73°F
76°F 77°F
Loop Temp < 45°F: 0 Hours (0%)
60°F
Poor application for Waterside Economizer
52
APPLICATION CONSIDERATIONS
Potential Waterside Economizer Hours (Grand Rapids)
Dry Bulb Bin Hours
Dry Cooler (10°F Range)
500
Loop Temp < 60°F: 1874 Hours (47%)
400
300
Loop Temp < 45°F: 1202 Hours (30%)
200
100
0
Geothermal
45°F
60°F
Loop Temp < 60°F: 3000 Hours (75%)
Wet Bulb Bin Hours
500
Loop Temp < 45°F: 1750 Hours (43%)
400
300
200
Cooling Tower (7°F Approach)
100
Loop Temp < 60°F: 2495 Hours (62%)
0
Loop Temp < 45°F: 1552 Hours (39%)
45°F
60°F
Good application for Waterside Economizer with Cooling Tower, Dry Cooler, or Geothermal
APPLICATION CONSIDERATIONS
Potential Economizer Operating Hours (Variable)
Dry Bulb Bin Hours
Dry Cooler Performance
1400
1200
Loop Temp < 60°F: Hours (0.04%)
1000
Loop Temp < 45°F: Hours (0%)
800
600
400
200
0
47°F
52°F
57°F 62°F
67°F
72°F 77°F
82°F
87°F
92°F
45°F 60°F
Geothermal Performance
Loop Temp < 60°F: Hours (0.05%)
Wet Bulb Bin Hours
Loop Temp < 45°F: Hours (0%)
1400
1200
1000
800
Cooling Tower Performance
600
400
Loop Temp < 60°F: Hours (7%)
200
0
43°F
47°F 51°F
45°F
56°F
61°F
65°F 70°F
73°F
76°F 77°F
Loop Temp < 45°F: Hours (0.04%)
60°F
54
Slide data depends on presentation location
APPLICATION CONSIDERATIONS
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
55
Photo Source: Carrier HAP v4.9
APPLICATION CONSIDERATIONS
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 Dominant
Heating Dominant
Building
Building
Heating
Cooling (Core Zones)
Cooling
(Core Zones)
Heating
(Perimeter Zones)
Perimeter Zones
56
Photo Source: Carrier HAP v4.9
APPLICATION CONSIDERATIONS
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)
57
APPLICATION CONSIDERATIONS
Minimize Economizer System Impact
Airside Pressure Drop
• Waterside Economizer coil mounted on unit return
adds to constant fan pressure
Waterside Pressure Drop
• When active, Waterside Economizer coil adds to the
pump head pressure
Heating Impact
• Low loop temperatures may impact WSHP heating
performance
58
Photo Source: FHP Manufacturing
APPLICATION CONSIDERATIONS
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 during
low ambient conditions, don’t use a WSE
Minimize Waterside Pressure Drop
• Use high efficiency pump motors
• Use variable speed pumps
59
Photo Source: Carrier Corporation
APPLICATION CONSIDERATIONS
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
60
Photo Source: Carrier HAP v4.9
APPLICATION CONSIDERATIONS
Heating System Impact
Entering Water Temperature vs. Supply Air Temperature
4.6
102°F
100°F
4.4
96°F
COP
4
94°F
3.8
92°F
3.6
Geothermal
Heating Loop
Temp
3.4
Standard
Range Heating
Loop Temp
3.7 COP
92°F SAT
3.2
4.2 COP
98°F SAT
90°F
88°F
Supply Air Temperature
98°F
4.2
86°F
4.5 COP
101°F SAT
84°F
3
82°F
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
Entering Water Temperature
COP
LAT
Data Source: Carrier WSHP Builder v6.0 All data based on: 2 ton base unit, 400 CFM/Ton
airflow, 68°F entering coil air temperature and 3 GPM/Ton condenser water flow.
61
APPLICATION CONSIDERATIONS
Heating System Impact
12,000
8°F
11,000
7°F
6°F
10,000
5°F
9,000
4°F
8,000
3°F
7,000
2°F
7,800 BTU
5.2°F ΔT
6,000
9,750 BTU
6.5°F ΔT
11,100 BTU
7.4°F ΔT
1°F
5,000
WSHP Water Temperature Drop
Boiler Load per WSHP Ton (BTU)
Effect of Water Loop Temperature on Boiler Load
°F
40°F
45°F
50°F
55°F
60°F
65°F
70°F
Water Loop Temperature
Boiler Load
WSHP ΔT
Data Source: Carrier WSHP Builder v6.0 All data based on: 2 ton base unit, 400 CFM/Ton
airflow, 68°F entering coil air temperature and 3 GPM/Ton condenser water flow.
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APPLICATION CONSIDERATIONS
Waterside Economizer System Example
9
10
1
2
3
4
8
6
5
7
Example
Office Building
(10) 2 Ton WSHPs
Boiler & Tower
68°F Loop Temp (No WSE)
45°F Loop Temp (No WSE)
ECM Fan Motors
800 CFM Each
6 GPM Each
Electric Boiler
Fan Hours: 500
Cooling Hours: 500 (Core)
Heating Hours 500 (Perimeter)
Compare systems with WSE
and without WSE
63
Photo Source: Carrier Corporation
APPLICATION CONSIDERATIONS
WSHP System without Waterside Economizer
System Performance without
Waterside Economizer
9
1
10
10
2
3
4
5
8
6
7
68°F
71°F
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
64
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
APPLICATION CONSIDERATIONS
WSHP System with Waterside Economizer
System Performance with
Waterside Economizer
9
2
1
10
3
4
8
6
5
7
45°F
47°F
Zone
Energy Consumption (kWh)
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
65
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
APPLICATION CONSIDERATIONS
Energy Consumption
No Waterside Economizer
With Waterside Economizer
Zone
Energy Consumption (kWh)
Zone
Energy Consumption (kWh)
1
570
1
120
2
570
2
120
3
570
3
120
4
570
4
120
5
570
5
120
6
570
6
120
7
638
7
788
8
638
8
788
9
638
9
788
10
638
10
788
Tower
305
Tower
275
Boiler
0
Boiler
0
Pump
1950
Pump
2000
Total:
8227 kWh
Total:
6145 kWh
HVAC Energy Savings: 25.3%
Source: Carrier Corporation 50PC Performance Data 50PC-09PD
66
APPLICATION CONSIDERATIONS
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
67
Photo Source: Carrier Corporation
QUESTION #5
Which of the following should be considered when
applying Waterside Economizers to WSHP?
A. Condenser loop temperature range capability
B. Local climate/ambient temperature
C. Heating system impact
D. All of the above
68
ASHRAE 90.1 ENERGY STANDARD
Overview
ASHRAE 90.1 is a standard that provides minimum guidelines for building
energy efficiency design for buildings (except low rise).
70
Source: ASHRAE Standard 90.1-2013
Purchased stock graphics BLDCM022 by permission
ASHRAE 90.1 ENERGY STANDARD
Waterside Economizers
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 (heating
impact)
Waterside Economizer Beneficial to Energy Cost Method
71
Source: ASHRAE Standard 90.1-2013
ASHRAE 90.1 AND WSE
Prescriptive Path
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)
Climate
Zone
Efficiency
Improvement
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%
72
Derived from: ASHRAE 90.1
ASHRAE 90.1 AND WSE
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
73
ASHRAE 90.1 AND WSE
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
74
Source: Interpretation IC 90.1-2010-15 of ANSI/ASHRAE/IES Standard 90.1-2010
QUESTION #6
In ASHRAE 90.1, which of the following impacts the
Waterside Economizer prescriptive requirement?
A. Unit capacity
B. Geographic location
C. Unit operating hours
D. All of the above
75
SUMMARY
WSHP Waterside Economizers
• Waterside Economizers can be a great fit for
Water Source Heat Pump systems
• Waterside Economizers are a powerful tool for
energy savings, when properly applied
• The negative impacts of Waterside economizers
can easily be overcome with smart design
choices
• Energy savings and code compliance are driving
forces behind Waterside Economizer use
77
SUMMARY
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.
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