understanding--- HVAC

Basic Concepts of Air Conditioning

Prepared exclusively

for

COACH LEATHERWARE

Panel

Moderator:

Bob Keingstein

Boss Facilities Services

631-361-7430

[email protected]

SOURCE OFCOOL AIR

• COIL •

HEAT

COILCOOL

AIR

TYPICAL ALL-AIR SYSTEM

S.A. DUCT

HEAT

COILCOOL

AIR

S.A.FAN


S.A. DUCT

HEAT

COILCOOL

AIR

S.A. TERMINAL

S.A.FAN


S.A. DUCT

HEAT

COIL

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

WARM AIR


R.A DUCT

S.A. DUCT

HEAT

COIL

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN


R.A DUCT

S.A. DUCT

HEAT

COIL

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN


R.A DUCT

S.A. DUCT

HEAT

R.A. DAMPER

COIL

FILTER

O.A.DAMPER

FRESHOUTDOOR

AIR

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN


R.A DUCT

S.A. DUCT

HEAT

R.A. DAMPER

COIL

E.A.DAMPER

FILTER

O.A.DAMPER

FRESHOUTDOOR

AIR

EXHAUSTAIR

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN

Economizer

• Provides cooling to space when outdoor air temperatures are below 55 degrees

• Switches over automatically from mechanical cooling

• Adjusts R.A. and F.A. dampers to maintain space temp

• May incorporate enthalpy control• Mandatory in some states based on unit capacity


R.A DUCT

S.A. DUCT

CHILLEDWATERPUMP

HEAT

R.A. DAMPER

COIL

E.A.DAMPER

FILTERWATER PIPING

WATERCHILLER

O.A.DAMPER

FRESHOUTDOOR

AIR

EXHAUSTAIR

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN


CONDENSERPUMP

R.A DUCT

S.A. DUCT

CHILLEDWATERPUMP

HEAT

R.A. DAMPER

COIL

E.A.DAMPER

FILTERWATER PIPING

COOLINGTOWER

HEAT

WATERCHILLER

O.A.DAMPER

FRESHOUTDOOR

AIR

EXHAUSTAIR

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN


CONDENSERPUMP

R.A DUCT

S.A. DUCT

CHILLEDWATERPUMP

HEAT

R.A. DAMPER

COIL

E.A.DAMPER

FILTERWATER PIPING

COOLINGTOWER

HEAT

WATERCHILLER

BOILER

O.A.DAMPER

FRESHOUTDOOR

AIR

EXHAUSTAIR

R.A. GRILL

COOLAIR

S.A. TERMINAL

S.A.FAN

R.A.FAN

Equipment Types

• ROOFTOP PACKAGE UNIT • SPLIT SYSTEM• CHILLED WATER AIR HANDLER• VARIABLE AIR VOLUME (VAV)• AIR TO AIR HEAT PUMP• Life expectancy 10 to 12 yrs for rooftop and split systems• Expect increase in repair costs as equipment ages• Typically largest expense to operation of store, energy/repair costs• Repair or Replace?

Single Package Roof Top Unit

•Most common

•Entire hvac system is located on mall roof

•Most common to have roof leaks from roof curb, condensate overflow or roof punctures


CONDR

COIL

COMP

FAN

HEAT

ELECTRICHEATER

S.A. DUCT

S.A.TERMINALR.A. DUCT

O.A.

E.A.

HEAT


• Rooftop package unit• Mounted on adaptor

curb• Power exhaust and

economizer installed

Split System

• HVAC system split into 2 pieces• Condensing unit located on roof (houses

compressor, condenser coil, condenser fan motor)• Air handler located in space above ceiling (houses

blower assembly, evap coil, air filters)• Connected electrically and with refrigerant piping• Most prone to refrigerant leaks especially if long

distance between components• Many times refrigerant lines are buried in

construction and inaccessible

SPLIT SYSTEM

COIL

HEAT

AIR

R.A. DUCT

O.A.

E.A.

FAN

CONDR

COMP

CONDENSING UNIT

REFRIGERANTLINES

S.A. DUCT

POSSIBLEELECTRIC

HEAT

AIR HANDLINGUNIT

OPTIONALSUPPLEMENTARY

HEATINGSYSTEM

HEAT

SPLIT SYSTEM

Split System

• Air cooled condensing unit

• Compressor, condenser coil and condenser fans

• Connected to indoor air handler

VAV BOX

•Consists of VAV terminal box located in the space above ceiling

•May have supplemental blower motor for positive airflow to space

•May have air filtration

•Has a damper inside that opens and closes on demand from thermostat to allow more or less airflow to space

Variable Air Volume

Major System Components

• Compressor• Condenser coil• Evaporator coil• Condenser fan motor• Evaporator fan motor• Thermostatic expansion valve• Evaporator blower assembly• Economizers (Optional)

HEAT REJECTION(“HIGH TEMPERATURE”)

85F

75F95F 55F

45F

CONDITIONEDSPACE

105F95F

HEAT GATHERING(“LOW TEMPERATURE”)

REFRIGERATIONMACHINE

(REFRIGERATION CYCLE)

35F

COOLINGTOWER

95F DB78F DB

HEAT

COMPRESSOR

COOLER

CONDENSER

Compressor

• This component is the heart of the system..• Pumps refrigerant and oil throughout

system• Separates the high pressure side of the

system from the low pressure side• If compressor fails, no cooling is possible

Condenser

• Condenser coil is what gets rid of the heat in the system

• Can be water or air cooled, however most are air cooled in retail application

• Located outdoors (air cooled)• Fins on coil are subject to corrosion in salt water

environment. Special coatings can be applied.• Fins are subject to damage from hail• Traps dirt and requires periodic cleanings

Evaporator Coil

• Provides cold air to the space• Located after the system air filters• Return air is blown over the coil and chilled• Removes moisture from air (condensate)• Traps dirt that gets past air filters, reducing

cooling capacity (95% is bacterial) • Requires periodic chemical cleaning

Evaporator Fan Motor

• Located behind condenser coil• Draws ambient air across condenser coil• System may have up to 4 or more motors based on

system capacity• Motors are direct drive with fan blades attached• Requires little if any maintenance (sealed

bearings)

TXV Thermal Expansion Valve

• Located at the evaporator coil• Provides the correct amount of refrigerant to the

evaporator coil for proper cooling• Separates the high pressure side of the system

from the low pressure side• Failure could cause compressor failure and loss of

system cooling capacity• Frequently overlooked in diagnosing system

problems• Requires manual setting of superheat for proper

operation.

Evaporator Blower Assembly

• Consists of:• Blower motor• Pulleys and fan belts• Bearings• Fan shaft• Fan wheels• Housings• Can be located indoors or outdoors

Control Types

• CONVENTIONAL THERMOSTAT• DIGITAL PROGRAMMABLE

THERMOSTAT• PNEUMATIC• LCD SYSTEM• MALL INTERFACE

Low Ambient Controls

• Low ambient controls• May be added to air cooled systems that must

operate when outdoor temperatures are below 55 degrees

• Cycles condenser fan/s to maintain correct system pressures

• Used when economizer is not present• Much less costly to install• Much more costly to operate

Conventional Thermostat

• Completely manual operation• Will maintain a single heat or cool setting• System must be switched from heat to cool• No energy savings• Will allow system to operate all night while store

is closed wasting energy• Easy to tamper with• Least expensive to install

Programmable Thermostat

• Provides auto changeover from heat to cool

• Provides up to 4 heat/cool settings per 24 hour period

• Can provide different weekend settings

• Keyboard can be locked out

• Set it and forget it

Pneumatic Thermostat

• Uses air provided by mall to operate thermostat

• Very commonly used with VAV systems• Least commonly found in malls• Parts are fairly expensive

LCD Thermostat

• Used in newer stores• Programmable type• Can be dialed into by monitoring company

for data

Rules Of Thumb

1HP = 1KW = 1KVA 1KW = 3413 BTU

1 Ton Cooling = 12,000 BTU 1 Ton = 400 CFM

Retail = 380 SQ FT/ Ton cooling

Delta T = 18°F across coil cooling Delta T = 25°F for heating

CFM = Building Volume in Cubic Feet

Minute/Air Change

Delta T = Difference between entering and leaving DB = ΔT

Servpro of Great Neck / Port Washington

For Further Information

Please Contact Us:

516-767-9600

ServproOfGreatNeck.com

http://servproofgreatneck.com/

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