Unit 36 and 37 HVAC

37.20 The air velocity of a 16-in. round duct is 800 Fpm; the airflow in the duct is __________cfm

1,120 CFM

The outside design temperatures in the summer in Tucson, Arizona for 2.5 % of the time are________________F. dry bulb and _________F. Wet bulb?

102 F Dry bulb and 66 F Wet bulb.

In the southwester United States on a 90 F, the condensing temperature for a standard air-conditioning system would be approximately ?

120 F

37.37 if there is more than___________difference between the air inside and the air outside the duct, it should be insulated?

15 F

37.21 If a rectangular duct system (12 in x 26 in.) has an average velocity of 700 fpm, what is the airflow?

1519 cfm

On January 1 of ______________, manufacturers were no longer allowed to use R-22 in new air-conditioning equipment

2010

The total production phaseout for R-22 will occur in?

2020

37.22 The Equivalent of pressure drop for a group of 3-G branch-line take off is ?

30 ft.

The solar load on a structure is the load resulting from the?

Heat from the suns radiation.

The design boiling point for most evaporator coils in residential air-conditioning is ____________________F

40 F

37.23 in a typical air-conditioning (cooling system, _________cfm of air is normally move per ton of refrigeration ?

400

37.1.1 The blower or fan provides the pressure difference to move the air typically how many cubic feet?

400 cubic feet and the air must be move per minute per ton of air-conditioning.

The air leaving the air handler in a typical air-conditioning system is approximately ______________at design conditions?

55 F

The split system ?

All the compressor and the condenser are located outside

37.12 Name four material used to manufacture duct?

Aluminum , Sheet steel, Fiberglass duct board, and flexible duct.

37.16 Zoning on air-conditioning or heating system allow for

Both A and B are characteritic of zoned systems

37.17 Multiple-Zoning systems often use a(n) ___________- or a(n) ___________ _____________ to alleviate the problem of excess air when only some zones are calling for conditioning

Bypass, dump zone

AIR TEMPERATURE OF AIR OFF EVAPORATIVE COLLER IS WHAT CONDITION ?

COOLER THAN THE AMBIENT AIR

IF WE ARE IN A EXPOSURE OF SAL AND SAND FROM BEACH AIR WHAT WULD BE TYPICAL COMBINATION OF THE METAL FOR THE CONDESING COIL OR EVAPORATOR COIL?

CORROSION FROM THE SAL AND THE SAND !! COOPER TO COOPER WILL BE IDEAL FOR THAT ENVIROMENT

Most compressor are cooled using the?

Cool suction Gas

37.1 Name five changes that are made to air to condition it ?

Cool, heat, dehumidify, humidify and clean

SPLIT SYSTEM AC WITH A REMOTE CONDENSER REFRIGERANT LINES WICH KIND MUST BE FIELD INSTALLED ?

DISCHARGE AND LIQUID LINE.

PUTING DUCT OR EXTENDING SECTION OF THE PLENUM TO GETHER WHAT IS THE NAME OF THE DEVICE CALL IT?

DRIVE CLIP AND S CLIP

37.5Name two types of blower drives?

Direct and belt drives

37.29 An extended plenum system is a type of

Duct system

The four major component of an air-conditioning system are

Evaporator, condenser, compressor, and metering device .

BURMID DOES NOT PERFORM BEST EFFICIENCY WHEN RUNING IN FULL LOAD?

FALSE

OVERSIDE DUCT SYSTEM ARE MORE INEXPENSIVE TO INSTALL TO RESULT IN THE AIR SLOWING DOWN AS IS CLOSE TO THE DUCT, TRUE OR FALSE?

FALSE

USING VIBRATION ELIMINATOR BETWEEN TWO SECTIONS METAL RUBBER OF THE DUCTS SHOULD BE RUBBERING EACH OTHER TRUE OR FALSE?

FALSE

TYPICAL EVAPORATOR AND CONDENSER ARE COOPER TUBE ON STAINLESS STEAL FIN TRUE OR FALSE?

FALSE COOPER TUBE WITH ALUMINUM FINS

HIGH EFFICIENCY CONDENSOR HAVE STAINLESS STEAL COILS TRUE OR FALSE?

FALSE, THEY HAVE MORE SURFACE AREA

1.- True or False? Evaporative air-conditioning will work in an climate?

False

37.14 True or false? If Air cooling circulates better throguh the conditioned space when it is introduced in the space through floor register?

False

37.18 True or False: Zoning an air-conditioning system can only be done when the system is initially designed and installed ?

False

FITING AT THE END OF A ROUND DUCT CONECT DUCT TO THE FLOOR REGISTER IS CALL TAKE OFF? FALSE IS CALLED REGISTER BOOTH

IN THE BOOTH

On a package air conditioning system, which refrigerant lines must be field installed?

IS A PACKAGE UNIT!!!!!!

ALUMINUM COILS HAVE A HIGH HEAT TRANSFER THAN STANDAR COOPER ALUMINUM COILS ? TRUE OR FALSE

IS TRUE AND COOPER ARE THE SAME HEAT TRANSFER ALUMINUM IS CHEAPER .

37.24 The pressure in a duct system is measure in?

Inches Water column

37.6 Pressure in ductwork is expressed in which of the following ?

Inches of water column

The supply-air duct in an air-conditioning system installed in an unconditioned space _______need to be insulated?

It does need to be insulated

What advantage does a capillary tube have over a thermostatic expansion valve?

Lees expensive and simpler

The small Interconnecting line between the indoor and the outdoor coil is the___________________line.

Liquid line

TH E REAZON FOR USING REDUCING EXTENDUM AIR SYSTEM IS TO PROVIDE

MANTIAN PRESSURE THROW THE ENTIRE AIR LINE.

37.34 To measure airflow by traversing the duct is too?

Measure the velocity of the airflow in a pattern across section of the duct and averaging the measurements

Home owner want to build new house vegas nevada to reduce or lower to solar load what side of the house will be most of the windwos should be on

North and south

The package type A/c what are the components located?

Package has all the component build in the cabinet .

37.27 Two types of fans are ?

Propeller and forward curved centrigugal

37.3 Which of the following types of fan is used to move large amounts of air agains a low static pressure drop?

Propeller fan

A refrigerant blend replacing R-22 in new residential and commercial air-conditioning applications is ?

R -410 A

The most popular refrigerant used in the past for residential air-conditionig is R-________

R-22

A refrigerant blend replacing R-22 in residential and commercial air-conditioning applications that can be used in retrofit applications is?

R-407 C

What refrigerant blend can be used in retrofit applications as a long-term replacement for R-22 in residential and light commercial air-conditioning applications?

R-407C

What are two high -efficiency refrigerant blends that can be used as long-therm replacements for R-22 in residential and light-commercial air conditioning applications?

R-410A and R-407C

What are the three most common types of compressor used in air-conditioning ?

Reciprocating, Rotary and Scroll

What are the advantages of using refrigerated air-conditioning than evaporative conditioning?

Refrigerated air-conditioning removes humidity, does not force fresh air in from the outside and makes it easier to control condition.

A compressor that has a stationary vane is the___________________compressor

Rotary

37.19 The duct sizes on the air friction chart are expressed in which of the following ?

Round .

What two types of heat are removed by the evaporator coil in the air-conditioning process?

Sensible heat and latent heat

37.30 A drive cleat is used when installing ____________duct systems

Sheet metal

37.15Why are dampers recommended in all branch-line ducts?

So the air volume can be balance for the correct flow to each run. Adjusting the air volume a the supply register can result in excessive noise .

37..32 The diffuser

Spreads the air from the duct into the desire pattern

37.25 Which of the following is typically measured with a manometer?

Static pressure in a duct system

two names for the interconnecting piping in a split air-conditioning system are

Suction (cool gas) and liquid.

The Large interconnecting line between the indoor and outdoor coil is the ___________line.

Suction Line

37.10 What is the component that distributes air in the conditioned space?

Supply and Register

EVAPORATOR THAT HAVE MORE THAN ONE SQUAL CIRCUIT WHY?

TO REDUCE PRESSURE OF REFRIGERANT GOINT THRUGH

37.13 The name of the fitting where the branch line connects to the main duct is the__________

Take off

37.31 The fitting between the main trunk and branch ducts in a duct system are called ?

Take off fittings

Thera are two basic types of A/c Units ?

The Package type and the split system

37.35 The static pressure in a duct system is ?

The force per unit are in a duct

The____________ Expansion device ordinarily must use a compressor with a high starting torque

Thermostatic

Two types of expansion devices in residential air-conditioning are ?

Thermostatic expansion valve and fixed-bore device.

More than one evaporator coil circuit may be use when ?

They would be excessive refrigerant pressure drop

37.4 True or false : Turbulence in airflow causes friction drop?

True

37.8 The three pressure created by moving air in ductwork are___________pressure.__________pressure, and __________________pressure

Velocity, Static and total-pressures

DUCT SYSTEM PRESSURE ARE MEASURE IN

WATER COLUMN

The fins on an evaporator coil are made of?

aluminum

air blown into a structure through an evaporative cooler (swamp cooler) tends to ____ than the outside air.

be more humid.

some heat leaks into a structure by ?

conduction, infiltration and radiation.

The thermostatic expansion valve?

does not allow the pressure to equalize during the off cycle unless specifically designed to do so

37.28 Squirrel cage blower are used in air-conditioning system primarily in_______________aplications?

ducted

High-efficiency condensers are ?

have more surface are than standard condenser

Dirty condenser coil can give you what problems?

high Pressure, and affect the eficency

infiltrated air of the same dry-bulb temperature may vary from one part of the country to another because of the difference in

humidity

37.9 Name the 2 types of return-air system in residential installations :

individual and central returns.

37.2 The two ways that air enters a structure are ____ and___________

infiltration and ventilation

What Advantages does a thermostatic expansion valve have over a capillary tube?

it maintains better control of the flow of refrigerant in the evaporator, more accurate superheat, and more active evaporator.

37.11 Warm air heats a room better if dirtributed ?

low in the room

37.7 What is a common instrumen used to measure pressure in ductwork?

manometer

The dew point temperature tells you how much ____________is in the air?

moisture

In the package air-conditioning system the evaporator will normally located ?

outside of the house

37.33 One reason for friction loss in duct system is the ?

rubbing action of the air on the walls of the duct

37.36 a Common way to fasten section of round galvanized steel duct to each other is by using ?

self-tapping sheet metal screws

The cooling for modern, reciprocating fully hermetic compressor used in air-conditioning is controlled by or directly from

suction Gas

The evaporator is a refrigerant coil made of aluminum or cooper with aluminum fins for what reason?

to give it more surface are a for a better heat exchange.

37.26 Velocity pressure is the ?

total pressure (-) minus the static pressure