Understanding HVAC HVAC Basics Definition of HVAC Benefits Air Handling HVAC Basics HVAC Vocabulary

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    Understanding HVAC

    Russ Schumacher

    Director of Design Services

    Nexus Solutions


    John Heck

    Project Manager


    Chippewa Falls, W



    HVAC Basics

    Systems & Components

    • Heating

    • Cooling

    • Hydronic

    • Air Handling

    • Geothermal

    • Controls

    • VFDs

    Maintenance Strategies

    Behavioral Based Energy


    Energy Consumption

    Questions & Answers

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    HVAC Basics

    Definition of HVAC


    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

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    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


    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)


    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




    Air Handling

    Geothermal – Heat Pumps


    System Types & Common Terms

    Unitary Equipment

     Direct Expansion

     Split System

     Heat Pump

     Packaged Rooftop Unit (RTU)



     Boiler

     Chiller

     Pumps and Valves


     Water Loop Heat Pump

     Radiant

    Air Distribution

    Constant Volume

    Variable Air Volume (VAV)


    Terminals/Fan Box




    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-


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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




    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


     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 Chiller Water 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


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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


     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





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    Air Handling Systems

     Air Handlers

     Univents

     Rooftop Units


    Air Handling Systems

     Air Handlers

     Univents

     Rooftop Units


    Air Handling System – Supplemental


     Warm Air Furnace

     Unit Heaters

     Radiant Heating (Direct &


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    Air Handling System - Distribution

    Constant Volume

    Variable Air Volume (VAV)


    Duct Sock

    Terminals/Fan Box


    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


     VAV System with Reheat

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    Air Handling System - Variable Volume


     VAV Box with Reheat Coil

    Air Handling System - Variable Volume


     VAV Box with Reheat Coil

     Fan Powered VAV

    Air Handling System - 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



    Direct Digital (Building Automation System)

    Electric Controls

    Electric Thermostat Control


    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

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    Variable Frequency Drive-VFD

    Air Flow

    Hot and Chilled Water Flow

    Incorporated Into Other Mechanical


    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

    Operation 50%

    Construction 11%

    Financing 14%

    Alterations 25%





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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