Unit 36 Refrigeration Applied to Air Conditioning

Question 1

Conduction

Answer 1

Form of heat transfer where heat energy is directly transferred between molecules through molecular collisions or direct contact.

Question 2

Radiation

Answer 2

Energy that is radiated or transmitted in the form of rays or waves or particles.

Question 3

Sensible Heat

Answer 3

Heat energy that brings about a change in temperature. Occurs in Conduction and Convection. lowers the air temperature.

Question 4

Latent Heat

Answer 4

Heat energy absorbed or rejected when a substance changes state and there is no change In temperature. changes the water vapor in the air to condensate.

Question 5

Convection

Answer 5

Heat transferred by the movement of fluids-liquids and gases

Question 6

Evaporative Cooler

Answer 6

Device for cooling homes in dry climates that cools the incoming air by humidifying it.

Question 7

The A coil

Answer 7

is used for upflow,downflow, & horizontal flow applications. it consists of two coils with their circuits side by side and spread apart by the bottom

Question 8

The Slant coil

Answer 8

is a one piece coil mounted in the duct on an angle (usually 60 degrees ) or slant to give the coil more surface area.

The slant of the coil causes the condensate water to drain to the condensate pan located at the bottom of the slant.

Question 9

The H coil

Answer 9

is normally applied to horizontal applications, although it can be adapted to vertical applications by using special drain pan configurations. the drain is normally at the bottom.

Question 10

the solar load on a structure is the load resulting from the :

Answer 10

heat from the sun’s radiation

Question 11

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

Answer 11

humidity

Question 12

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

Answer 12

be more humid

Question 13

in a package air-conditioning system, the evaporator will normally be located

Answer 13

Outside the house

Question 14

the fins of an evaporator coil are made of

Answer 14

aluminum

Question 15

more than one evaporator coil circuit may be used when

Answer 15

there would be excessive refrigerant pressure drop

Question 16

the cooling for modern reciprocating fully hermetic compressors used in air conditioning is controlled by or directly from

Answer 16

The suction gas

Question 17

a compressor that has a stationary vane is the ____ compressor

Answer 17

Rotary

Question 18

high efficiency condensers

Answer 18

have more surface area than standard condensers

Question 19

two types of expansion devices used in residential air conditioning are the thermostatic expansion valve and the :

Answer 19

fixed-bore device

Question 20

the thermostatic expansion unit (TXV)

Answer 20

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

Question 21

the air leaving the air handler in a typical air-conditioning system is approximately

Answer 21

55 degrees fahrenheit

Question 22

the supply air duct in an air conditioning system installed in an unconditioned space______(does or does not) need to be insulated

Answer 22

Dose

Question 23

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

Answer 23

suction(cool gas) and liquid

Question 24

in the southwestern united states on a 90/f day, the condensing temperature for a standard air-conditioning system would be approximately

Answer 24

120/f …. 90 + 30=120

Question 25

a refrigerant blend replacing r-22 in new residential and commercial air-conditioning applications is

Answer 25

R-410A

Question 26

A refrigerant blend replacing R-22 that can be used in a retrofit application

Answer 26

R-407C

Question 27

by the year _____ R-22 can no longer be used in new air conditioning equipment

Answer 27

2010

Question 28

the total production phase out for R-22 will occur in

Answer 28

2020

Question 29

a dirty condenser coil can lead to

Answer 29

reduced efficiency, increased head pressure

Question 30

a home owner plans to build a house out in Las Vegas, Nevada, in the middle of the desert. It would be in his/her best interest to lower the "solar load ", to locate most of the windows on the ________and________ sides of the house

Answer 30

North & south

Question 31

Under what conditions would a package air-conditioning system need to be charged?

Answer 31

during compressor replacement, after the suction line is cracked.

Question 32

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

Answer 32

None

Question 33

on a split air conditioning system with a remote condenser/condensing unit which refrigerant lines must be field installed?

Answer 33

Liquid & suction

Question 34

the air temperature of the air "off" an evaporative cooler is

Answer 34

cooler than the entering air

Question 35

in reciprocating and scroll type motor-compressor assemblies , the motor is cooled by ______

Answer 35

suction gas returning to the compressor

Question 36

in ROTARY type motor-compressor assemblies, the motor is cooled by _______

Answer 36

discharge gas from the compressor

Question 37

The most popular material combination used in air conditioning evaporators and condensers is

Answer 37

copper-tube aluminum fin

Question 38

when exposed to salt air , the material combination used in air conditioning evaporators and condensers may be____

Answer 38

copper tube-copper fin

Question 39

when an "A" coil is used in a horizontal application , the coil is laid on its side and a special______ is required

Answer 39

drainpan

Question 40

slant coils for downflow application are designed with a coil slant of _______degrees

Answer 40

60 (degrees)

Question 41

A compressor that uses a stationary vane / rotating vane is the _________type

Answer 41

Rotary

Question 42

Three types of expansion devices are used in residential air conditioning systems. they are _______,_______, & _____.

Answer 42

TXV,Fixed bore,Orifice

Question 43

There are two types of Attic Ventilation

Answer 43

power and natural

Question 44

Three common coil evaporator designs used in air conditioning equipment ?

Answer 44

The A coil, The Slant coil, The H Coil

Question 45

A field technician installed two side air discharge condensing units next to each other so that the discharge air of unit "A" feeds into the condensing unit "B" . what is likely to happen?

Answer 45

Unit "A" will work fine while unit " B" will not reject heat as well

Question 46

on a multi- directional air handler ( an air handler that can be mounted as a right flow, left flow, or up flow) what must the installing technician remember to do before connecting ?

Answer 46

install proper drip pan , make sure air handler is mounted in the correct direction

Question 47

if a high efficiency condensing unit is manufactured with a one-speed condenser fan motor,what is likely to happen if the system is operating during mild weather?

Answer 47

If the fan is high speed then the condensers would be too efficient in mild weather resulting in low head pressure, starving the expansion device and resulting in less capacity

Question 48

what is the major ADVANTAGE a top air discharge condensing unit has over a side air discharge condensing unit?

Answer 48

The hot air and noise are discharged from the top of the unit into the air...

Question 49

what is the major DIS-ADVANTAGE of a top air discharge condenser over a side air discharge condenser?

Answer 49

the fan and the motor are at the top of the equipment ,and rain,snow, and leaves can fall directly into the unit.

Question 50

Heat leaks into the structure by

Answer 50

Conduction, infiltration, and radiation