Unit 36 Refrigeration Applied to Air Conditioning

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

liquid & suction

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

none

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

outside the house

There are two types of Attic Ventilation

power and natural

a dirty condenser coil can lead to

reduced efficiency, increased head pressure

a compressor that has a stationary vane is the ____ compressor

rotary

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

suction gas returning to the compressor

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

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

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

the suction gas

more than one evaporator coil circuit may be used when

there would be excessive refrigerant pressure drop

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

120/f .... 90 + 30=120

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

2010

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

2020

Heat leaks into the structure by

Conduction, infiltration, and radiation

evaporative cooler

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

radiation

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

conduction

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

latent heat

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.

sensible heat

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

convection

Heat transferred by the movement of fluids-liquids and gases

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?

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

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

North & south

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

R-407C

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

R-410A

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

Rotary

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

TXV,Fixed bore,Orifice

Three common evaporator designs used in air conditioning equipment ?

The A coil, The Slant coil, The H Coil

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

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

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?

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

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

suction(cool gas) and liquid

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

55 degrees fahrenheit

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

60 (degrees)

the fins of 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

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

cooler than the entering air

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

copper tube-copper fin

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

copper-tube aluminum fin

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

discharge gas from the compressor

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

does

the thermostatic expansion unit (TXV)

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

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

drainpan

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

during compressor replacement, after the suction line is cracked.

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

fixed-bore device

high efficiency condensers

have more surface area than standard condensers

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

heat from the sun's radiation

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

humidity

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 ?

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

The Slant coil

is a one piece coil mounted in the duct on an angle (usually 60F) 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.

The H coil

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.

The A coil

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