hvac fundamentals

HVACFundamentals

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Objectives

• Basic industry terms• Basics of BMS and HVAC

To gain familiarity with:

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Why have Controls and BMS ?

Safety

• of People

• of equipment

Economy

• Save money

• Use just the right amount of energy (electric power, gas etc.)

• Increase equipment life by using it efficiently

• Protect equipment and products (avoids wastage - paintings in a gallery, drug/chemical stores)

• People’s productivity

Comfort

• Too hot/cold

• Too dry/humid

• Too polluted

• “Sick Occupancy”

• Health and Safety

• 21 Deg C/ 50% RH

•24 Deg C/ 50% RH

• Enough Fresh Air

• Clean Air

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Why have Controls and BMS ?

Comfort

• Need to ADD/REMOVE heat and/or moisture

• Need to clean (filter air) and supply adequate fresh air

People lose heat (feel cold) - amount they lose depends on temperature around them - cooler it is, more heat they will lose through their skin

OR they “generate” heat (feel warm/hot - WORK TOO HARD!) - need to cool them down by reducing air temperature around them

People feel “muggy” - the air around them has too much moisture

People feel “dry” - not enough moisture in the air around them

Buildings (where people live and work) also lose or gain heat (through walls, Windows, floors, roofs, heat generating equipment e.g. VDUs, and computer equipment)

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Why have Controls and BMS ?

Safety

• Need to provide protection against equipment running “wild” / out of control

• Need to make sure people are safe at all times

Can’t have coolers or heaters (boilers) running “wild” - they might freeze up or blow up!

If too hot or cold for long period of time - affects their health

Sometimes you have special needs for process (making capsules, fiber, etc)

Hospitals may have special needs for patients / medicines / labs

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Why have Controls and BMS ?

Economy

• Use energy efficiently - use plant efficiently - make people comfortable (they will produce more???)

Electric power or fuel (gas, coal, oil) is expensive and limited (?)- need to use efficiently

Environmental issues (Clean atmosphere for the occupants)

Need to ensure maximum return on investment - prolong equipment life and get the best out of it

Increase productivity of people increased profits for offices, hotels, etc.

Ensure that products you are making/ supplying (e.g. supermarket) do not deteriorate because of bad “environment”

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• How do you heat / cool your home?

• How does the heating / cooling know when to turn on?

• How does the Hot / Chilled water turn on and off ?

You already know Controls.....

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• What does the thermostat do?

• What does the A/C do?• What does a radiator do?• .. and the time switch?

In your home

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• Larger areas to be heated or cooled therefore bigger equipment (e.g. Chillers, pumps, valves)

• Different types heating/cooling equipment are used.• Operational needs are different e.g.

• different areas of the buildings occupied at different times• different areas have differing heating/ cooling requirements• Central monitoring point for Building Energy Management

System

Air-conditioning in large buildingsBasic issues are same - Comfort, Safety, Economy, BUT

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• People working in the industry refer to Wet and Dry Systems in a building

Wet & Dry Systems?

Wet Systems:• Any systems to do with water e.g.

– Chillers (cool Water)– Boilers (heat water)– Pumps (makes water flow in

pipes)– Valves (regulates amount of

water flow through heating or cooling “radiators” or coils

Dry Systems:• Any systems to do with Air e.g.

– Fans (makes air flow in ducts)– Filters (clean air)– Dampers (regulates amount of

Air flow through the ducts)– Air handling units (cools,

heats, filters air - ALL IN ONE)

Need to CONTROL and/or MONITOR both Systems

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• Control and Monitor• Room (Air) temperature, humidity, ventilation• Chillers (chilled/cold water services)• Boilers (Hot water services)• Pumps• Fans• Lights• Flow

Managing large building?

• What types of buildings and facilities do you think can use controls and BMS? – Any building

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Introduce HVAC?

Heating

Increase orDecrease the water or Air Temperature

BoilersRadiatorsPumps

Ventilating

Supply right amount of

Clean fresh air

FansAir Ducts(?)Dampers(?)

Air Conditioning

ALL IN ONE - HANDLES ALL

Cool Air

Heat Air

Clean Air

Add Moisture

Remove Moisture

Move air

Recover wasted Heat

AirHandling

Unit(AHU)

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HVAC System in a Building

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Basic of Refrigeration

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Refrigerationis

COOLCOOL

How it Works

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THERETHEREIS NO COOLIS NO COOLONLY ONLY HEATHEAT

AS LONG AS THERE’S ATOMIC MOTION AS LONG AS THERE’S ATOMIC MOTION

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Cold can’tbe given to an object.

Heat must be removed. 05/0

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A Refrigeration System is a Heat Moving Machine

Condenser

Evaporator

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Typical Refrigeration System

Low Pressure VaporLow Pressure LiquidHigh Pressure LiquidHigh Pressure Vapor

Legend

Liquid Refrigerant Receiver

Evaporator

Condenser

Compressor

TX Valve

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Air Handling Unit

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Air Handling Unit

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Fan Coil Unit (FCU)

Room Units

Variable Air Volume (VAV) box

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Packaged Units

Complete Room A/C Units

Split Air Conditioning Units

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HVAC Air Systems• HVAC air systems are made up of:

• AHU - Air handling units • Dampers• Coils and Valves• Fans • Distribution ducts and terminal boxes• Pumps and Plumbing• Control devices and control loops• Unitary equipment: fan coils, perimeter

radiation, unit ventilators, unit heaters, etc.

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AHU - Components & Terminology

RAEA

OA

Return From Space

FilterCooling Coil

Heating

DA

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AHU components

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What are Functions of AHU ?• Function:

• Condition the air• Heat the air• Cool the air• Dehumidify the air• Humidify the air• Clean the air• Distribute the conditioned air into the

building space.• Commercial air handling units can be

compared to home furnaces.

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Air Handler ComponentsThe damper section :• Manually Operated for

Outside Air/Exhaust Air

• Motorized Modulating

• Motorized On/Off

• Fire Dampers – Motorized / Fuse Link Operated

Air Handler ComponentsThe fan section with

access door open.

Air Handler ComponentsFilters :Types of Air Filters Pre Filters

Fine Filters

HEPA Filters

ULPA Filters (Ultra Low Penetration Air)

Air Handler Components

• 70-80-% Efficiency .

• Can filter particles of size upto 5-10 microns.

• Reusable & Washable

PRE-Filters

Air Handler Components

•90-95 % Efficiency .

• Can filter particles of size upto 1 to 2 microns.

• Not Reusable

Fine Filters

Air Handler Components

• 99.97-% to 99.99995 % Efficiency .

• Can filter particles of size upto 0.1 to 0.3 microns.

• Used in Clean Room Applications.

•Not Reusable

High Efficiency Particulate Air Filters (HEPA)

Air Handler ComponentsThe filter section.Notice the cross stacking

of the filters to increase surface area.

Air Handler ComponentsTemperature Sensor:• Temperature sensors are used for

measurement of temperature of a Room, Air Duct, Hot /Cold Water, Outside Air etc.

• Models are available with PT1000, NTC20K, BALCO500 sensing elements.

LF20 : AIR DUCT TEMP. SENSOR (NTC 20k)

T7412 : ROOM TEMP. SENSOR (PT1000/NTC 20k)

T7413A : IMMERSION TEMP. SENSOR (PT1000)

Air Handler ComponentsRelative Humidity Sensor:• Relative Humidity sensors are used

for measurement of Relative humidity of a Room, Air Duct, Outside Air etc.

• Sensor Type : Capacitance • Combined Relative Humidity and

Temperature Sensors are available with PT1000, NTC20K, BALCO500 sensing elements.

H7015 : DUCT RELATIVE HUMIDITY SENSOR

H7012 : ROOM RELATIVE HUMIDITY SENSOR

Air Handler ComponentsDifferential Pressure

Switch:• Differential Pressure switches are

used for monitoring of Filter, Fan, Pump, Fire Damper, Water Flow, Air Flow Status of air handling systems.

DPS1000 : AIR DIFFERENTIAL PRESSURE SWITCH

TDIAP SERIS : AIR FLOW SWITCH

Air Handler ComponentsDifferential Pressure

Sensors/Transmitter:• Used for measuring diff. Pressure,

positive pressure and vacuum.

DPT1000 : AIR DIFF. PRESSURE TRANSMITTER

ST 3000 Pressure Transmitter

Air Handler ComponentsCoils :Cooling Coils Heating Coils

Coil Construction

• Copper with Aluminium fins,

• 13 Fins /inch

• Number of Rows, I.e 4/6/8 depending on the latent heat load & Bypass Factor.

Air Handler ComponentsThe coil section of a AHU.

Note:There may be a wide variety of actual configurations

Air Handler ComponentsValves & Actuators

Valve Types 2 Way or 3 Way

Actuator Types Motorised Magnetic Pneumatic

Operation On - Off,Floating, Modulating

Air Handler ComponentsEnergy Recovery :

A energy-recovery system is often used in buildings where a significant quantity of outdoor air is used. Several types of heat-recovery systems are available Heat pumps Runaround systems Rotary heat exchangers Heat pipes.

Runaround systems

Heat Wheel

AHU Coil ControlThe air handler cooling component is accomplished via chilled water coils or via a refrigerant evaporator coil absorbing heat in the air stream.

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Practical ExampleMixed Air AHU :

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Practical Example100% Outside Air AHU :

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Plant

Chiller Plant

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Chiller PlantChiller Plant systems are made up of:

– Chiller/Condenser Unit– Chilled Water Pumps– Condenser Water Pumps– Cooling Towers – Makeup Water Tank– A/C Expansion Water Tank

TRANE Chiller

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Typical Commercial Chillers

What can we control on this system?

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Chiller PlantChiller Plant Concept :

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Typical Cooling Tower

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Typical Chiller Plant

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Boiler PlantBoiler Plant systems are made up of:

– Boiler Units– Primary Pumps– Secondary Pumps

Typical Firetube Boiler

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Typical Commercial Boiler System

What can we control on this system?

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Boiler Plant

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Questions ?? 05/0

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