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Understanding HVAC
Russ Schumacher
Director of Design Services
Nexus Solutions
John Heck
Project Manager
CESA10
Chippewa Falls, W
Agenda
HVAC Basics
Systems & Components
• Heating
• Cooling
• Hydronic
• Air Handling
• Geothermal
• Controls
• VFDs
Maintenance Strategies
Behavioral Based Energy
Management
Energy Consumption
Questions & Answers
2
HVAC Basics
Definition of HVAC
Benefits
Air Handling
HVAC Basics
HVAC Vocabulary
Measurable Parameters
Temperature (Dry Bulb/ Wet Bulb)
Pressure
Humidity
Indoor Air Quality (CO, CO2, odor,
VOC’s, particulate, etc.)
Ventilation Air – Outdoor Fresh Air %
Air Changes/Air Flow (CFM)
kWh/ft2, BTU/ft2
British Thermal Unit (Btu) = Heat required to
raise 1 lb of water 1 degree F
Ton of Cooling = Heat required to melt 2000
lb of ice in 24 hours (12,000 Btu/hr)
$/ft2
Psychometric Chart
3
Students in well-maintained facilities score 11%
higher on standardized tests.
A study of the District of Columbia school system found, after controlling for
other variables such as a student's socioeconomic status, that students'
standardized achievement scores were lower in schools with poor building
conditions. Students in school buildings in poor condition had achievement
that was 6% below schools in fair condition and 11% below schools in
excellent condition. (Edwards, 1991)
Similarly, Hines' (1996) study of large, urban high schools in Virginia also
found a relationship between building condition and student achievement.
Indeed, Hines found that student achievement was as much as 11 percentile
points lower in substandard buildings as compared to above-standard
buildings.
Main purpose of HVAC (heating, ventilating, and air
conditioning) systems is to provide occupants with
"conditioned" air so that they will have a comfortable and safe
work (learning) environment
"Conditioned" air means that air is clean and odor-free, and
the temperature, humidity, and movement of the air are within
certain comfort ranges
“Ventilation” air is the amount of code required outdoor fresh
air required by the space (Varies with space type)
CONSIDERATIONS DURING DESIGN
1. Budget tolerance of School Board
2. Amount of addition vs. size of
existing building
3. Available floor to ceiling height
4. Building footprint – single-story
with a sprawling footprint
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Systems & Components
Heating
Cooling
Hydronic
Air Handling
Geothermal – Heat Pumps
Controls
System Types & Common Terms
Unitary Equipment
Direct Expansion
Split System
Heat Pump
Packaged Rooftop Unit (RTU)
PTAC/PTHP
Hydronic
Boiler
Chiller
Pumps and Valves
Other
Water Loop Heat Pump
Radiant
Air Distribution
Constant Volume
Variable Air Volume (VAV)
Ductwork
Terminals/Fan Box
Dampers
Controls
Pneumatics
Direct Digital Controls (DDC)
Heating Systems
Types of Boilers
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Heating Systems – Hot Water
Non-Condensing Boiler Fire Tube Boiler
Modulating
Heating Systems – Hot Water
Non-Condensing
Water Tube Boiler
Modulating
Heating Systems – Hot Water
Higher Efficiency
Boiler - modulating
Condensing vs. Non-
Condensing
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Heating Systems – Hot Water
Higher Efficiency Condensing Boiler Function
Cooling Systems
Refrigeration Cycle
Types of Systems
Unitary Equipment
Cooling Systems - Refrigeration Cycle
Expansion Device
Compressor
Evaporator
Condenser
Heat Extracted
Heat Absorbed
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Cooling Systems - Unitary Equipment
Pre-Engineered, Factory
Assembled, Site Hook Up
Window AC Units
Packaged Terminal AC
(PTAC)
Rooftop Units (RTU’s)
Cooling Systems
Direct Expansion Examples Air Cooled Condensing Units
Compressor Condensing Unit
Mini Split Systems
Cooling Systems
Air Cooled Direct
Expansion ChillerWater Cooled Centrifugal Chiller
Cooling Tower
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Heat Pump Cycles
Cooling Mode Left Heating Mode Right
Hybrid Heating/Cooling—Water Loop
Heat Pump
Hydronic Systems
Applications
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Hydronic Systems
Hydronics is the name for the use of water as the heat-transfer medium
in heating and cooling systems.
Water has a higher specific heat capacity than air, reducing size of heat/cool delivery
system.
Water valves (temperature control valves) v. dampers for control
Heating Systems
Boilers, Pumps, Heat Exchangers
Cooling Systems
Chillers, Pumps, Cooling Towers, Heat Exchangers
Hydronic Systems – Hot Water
Centrifugal Pumps
Base mount or in-line
Valves
Heat Exchangers
Air Handling Systems
Systems
Distribution
VAV’s
Dampers
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Air Handling Systems
Air Handlers
Univents
Rooftop Units
(RTU’s)
Air Handling Systems
Air Handlers
Univents
Rooftop Units
(RTU’s)
Air Handling System – Supplemental
Equipment
Warm Air Furnace
Unit Heaters
Radiant Heating (Direct &
Indirect-Fired)
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Air Handling System - Distribution
Constant Volume
Variable Air Volume (VAV)
Ductwork
Duct Sock
Terminals/Fan Box
Dampers
VFDs on Fans
Chilled and HW Coils
Air Handling System - Air Distribution
• Constant Volume
• Hard Duct and Diffuser
• Duct Sock
Air Handling System - Variable Volume
Systems
VAV System with Reheat
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Air Handling System - Variable Volume
Systems
VAV Box with Reheat Coil
Air Handling System - Variable Volume
Systems
VAV Box with Reheat Coil
Fan Powered VAV
Air Handling System - Dampers
Dampers
Shut off
Fire
Smoke
Control
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Geothermal Systems
System Application
Types of Geothermal Wells
Life Cycle Cost
Geothermal System
Geothermal System
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Geothermal Systems
Horizontal Field
Geothermal Systems
Vertical Field
Geothermal Systems
Geothermal Pond
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Geothermal Systems
Control Systems
Electric
Pneumatic
Direct Digital (Building Automation System)
Electric Controls
Electric Thermostat Control
Applications:
Unit Heater
Fan Coils
Electric Heating
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Pneumatic Controls
Pneumatic Control Air
Compressor and Panel
Controls Network
Stand Alone Building Automation System
Networked Building Automation System
Controls Network – BAS Graphic
17
Variable Frequency Drive-VFD
Air Flow
Hot and Chilled Water Flow
Incorporated Into Other Mechanical
Equipment
Variable Frequency Drives-Air Handling
Double Duct System with Fan Tracking
Variable Frequency Drives
Primary Secondary Pumping Applications
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Variable Frequency Drives within Equipment
Maintenance Strategies
The History of Maintenance Evolution
Fitting the Right Strategy
In a Perfect World…..
Total Cost of Operation
ASHRAE – American Society for Heating,
Refrigeration & Air Conditioning Engineers
Operation50%
Construction11%
Financing14%
Alterations25%
Operations
Budgets
Capital
Budgets
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Maintenance Strategies
Reactive
Preventive
Predictive
Reactive Maintenance
“Reactive maintenance, also known as breakdown maintenance, are
repairs that are done when equipment has already broken down.
Reactive maintenance focuses on restoring the equipment to its normal
operating condition.”
•Least efficient and most costly method of equipment maintenance
Fiixsoftware.com
Preventative Maintenance
“Preventative maintenance is maintenance that is regularly performed on
a piece of equipment to lessen the likelihood of it failing. Preventative
maintenance is performed while the equipment is still working, so that it
does not break down unexpectedly.”
•Most common type of equipment maintenance
•Based on ANSI standards
•Helps to maintain the efficiency and longevity of equipment
Fiixsoftware.com
20
Preventive Weakness
“The best time to determine how well a piece of equipment is running is
when it is running”.
“Prevention tasks are almost always performed when the equipment is
down and most detection tasks are performed when the equipment is
running”.
•Predictive Maintenance can be used to supplement preventative
maintenance to “predict” failure based on set metrics.
J. Richard Word, CMRP, 2004
Predictive Maintenance
Predictive Maintenance is the process of analyzing the condition of
operating equipment to predict, through a series of predetermined
metrics, when equipment may fail and to perform maintenance at that
optimal time.
• More cost effective than preventative maintenance since maintenance
is performed as needed not based on a regular interval.
• Helps to maintain the efficiency and longevity of equipment
• Can identify potential failures that preventative maintenance would not
normally address
Thermal Image of a Roof – Leak Detection
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Thermal Image of Electrical Components – Hot Spot is Point of
Potential Failure
Energy Management
Understanding Energy
Behavioral Based
Operations Management
Equipment
How do you manage energy?
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Understanding Energy
Concepts for staff to understand:
kilowatt hours (kWh)
kW or Demand
Therms
Efficiencies of Equipment
Return on Investment or Pay Back
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kW (
ave
rage
po
we
r o
ver
15
-min
ute
inte
rval
)
Time (15-minute intervals)
Example Single day profile
Behavior Change
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How do you identify behavior-related energy saving
measures?
• Energy Manager
– Surveys
– Observations
– Energy Teams
• Vendors
• On your own – trainings/seminars
Identifying Savings
Benefits of Behavior-Based
Energy Management
Facilitate a culture change so that energy conservation is
not an ‘add-on’ but a part of the school culture
(CULTURE CHANGE)
Engage staff in way where their voice is heard and energy
expectations are clearly communicated with rationale
(COMMUNICATION)
Efficient equipment will only get you so far… the people
operating the equipment need to understand why and how
or they will slip into old, inefficient routines (EDUCATION)
Operational Change
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Invest in a BAS and schedule areas for occupancy
Eliminate pneumatic controls when possible
Stagger start times to reduce peak demand
Standardize heating/cooling set points
Use high efficiency motors and system components
Perform preventative maintenance to optimize equipment
Re-commission older systems to ensure proper operation
Identify Operational Savings Opportunities
Questions and Answers
Thank You
