ESCO Air Conditioning Certification

sensible heat

Heat that causes change in temperature of a substance

latent heat

Heat that is added with out a rise in temperature

super heat

Heat added to refrigerant in vapor state after evaporation process is

involute spirals

Scroll compressor moves refrigerant by means of

convection

movement of heat by way of fluid or air

conduction

movement of heat by way of solid

BTU

Standard unit for measuring heat

Condensor

refrigerant gives up heat in the

liquid slugging

refrigerant in suction line must be slightly warmer than the saturation temperature to prevent

low

state of refrigerant in the suction line is ____ pressure _____ temp vapor

High

state of refrigerant entering the condensor would be ______ pressure ______ superheated vapor

evaporator

transfers heat from refrigerated space to the refrigerant

flammability

which is not a thermo-dynamic property of refrigerants

Compression, condensation, expansion and vaporization

the sequential order of steps in vapor-compression process

201 psig

30 lbs cylinder of R410A sits overnight at 70 degrees would have a pressure of

inches of water column (WC)

fan airflow pressures are usually measured in

0 psia

pressure that cannot be further reduced

0 psig

the same as atmospheric pressure

dew point temp

the temp at which moisture will start to condense from the air is the

pressure and vacuum

compound pressure gauge measures

open drive compressor

a mechanical shaft seal is necessary on an

liquid slugging

liquid refrigerant in the compressor clearance space

clearance space

has an effect on compressor capacity in a reciprocating compressor

scroll

which type of air conditioning compressor is the most effecient

De-superheat, condense and subcool

what is the right order of function in a condensor

air cooled, water cooled and evaporative

3 basic types of condensors

sensible and latent

heat removed from refrigerant by condensor is both _____ and ______

energy recovery ventilator

what uses an air to air heat exchanger to recover heat

30 degrees hotter than the air entering

when testing the efficiency of an air cooled condenser the refrigerant condensing temp should be approximately

10 degrees hotter than the air entering

When testing efficiency of a water cooled condenser the refrigerant condensing temp should be approximately

de-superheat

First function of a condensor is to ____________________ before condensing can occur

TXV

A _______ is designed to maintain constant superheat

Auto Expansion Valve

______ ______________ _________ maintains constant evaporative pressure

evaporative, spring, sensor bulb

Thermo Expansion valve (TXV) has 3 pressures _____________________, _________________, and ___________________

lower than valve body

When mounting TXV sensor bulb, you do not install it _________________________________________________ .

warmer

In an air conditioning system that uses TXV, the temp of the evaporator outlet will usually be ______________ than evaporator inlet

fairly constant

Auto expansion valve (AXV) is best suited when the system load remains ___________ ______________.

evaporator temp

Capillary tubes do not maintain constant _________________________________ .

close

A decrease in superheat causes the TXV to begin to ___________.

close

A rise in evaporator pressure causes AXV to ___________.

NTC Thermistor

A thermal electric (solid state) expansion valve is controlled by _______ _______________.

mixture of liquid and flash gas

In a direct expansion evaporative system, the refrigerant enters the evaporator as a ________________________________________________________ .

coil to the condensing unit and latent/sensible load

Most important consideration in evaporator coil selection is to match the _______________________________________________

evaporator

In the ______________________ latent heat is transferred from refrigerated space to the refrigerant.

condensor and metering device

The liquid line filter dryer should be placed between the____________________________________________ .

sub-cooling

The only way to minimize flash gas is by ____________________ the liquid refrigerant.

Liquid receiver

______________ _______________ is used to store the liquid refrigerant.

Accumulator

The ________________________ keeps liquid from getting to the compressor

Site glass

_______ __________ is located in the liquid line before the metering device

bubbles in sight glass

_____________________________________ indicate refrigerant blend with a high temp glide

discharge line

Oil separator is installed in the ______________ ______.

metering device

A solenoid valve pump in a down system is located before the ____________ _____________.

Keep pressure from falling below limit

The purpose of the evaporator pressure regulating valve is to ___________________________________________________.

liquid sub-cooling

A liquid-to-suction heat exchanger is often used to increase ___________ _________________.

Oil pressure safety switch

______ ____________ __________ __________ is opporated by the difference between crank case pressure and oil pressure.

Low

_______ pressure cut off switch is used to establish a minimum opporating pressure

undercharge

Partially iced over evaporator coil can be caused by an ___________________________.

soap bubbles

_________ ____________ can be used for leak detection with all high pressure systems

40-70%

The flow rate of a R410A system is ___________ higher than that of R22

1 in

An electronic leak detector should be used at ___________ every 2 seconds

100 degrees

10 lbs. of refrigerant passing through a water cooled condenser will lose 20 Btu's of heat per lb. if 10 lbs of water passes through the condenser with an entering temp of 80 degrees. The temp. of the water leaving the condenser is

stopped up filter drier

a temperature differential across a filter drier indicates a

compressor failure

Moisture in a refrigeration system will cause _____________ _____________

Electronic vacuum gauge

_____________ _____________ __________ will measure microns

100

Water will vaporize at ___________ degrees F in a 28 in vacuum

Replace filter dryer, leak check, evacuate, charge

After a system has been opened and the compressor changed _____________________________, _____________, _______________________, and _______________.

500 microns

To remove as much moisture as possible from a system, triple evacuate the system to _______ ____________

124 psig

R134A vapor enters the condenser at 124 psig, 100 degrees Fahrenheit it leaves the condenser at 80 degrees fahrenheit its pressure will be approximately

compressor

it is desirable for refrigerant in the suction line to be slightly superheated in order to insure liquid refrigerant does not enter

high discharge line pressure and low liquid line pressure

What would be indicative of an oil logged condenser

12

A 410A system has compound gauge reading of 54 degrees F at 124 psig, the super heat would be _______ degrees F.

liquid into low side

When topping off an operating system using a blended refrigerant, introduce ________________________________________ while throttling the valve.

starved evaporator

Partially clogged capillary tube can cause_____________ _____________.

15

R134A high pressure gauge reads 146 psig and the liquid line temp at condensing unit is 95 degrees, the sub-cooling is _______ degrees F.

Increased head pressure

Overcharged refrigerant will cause an ____________ ______ ______________

dirty evaporator

Complaints that the air system runs constantly but there is no cooling would be ___________ __________________

negative

Drain trap should be installed on split system when air handler drain is on _______________ side of evaporator.

debris in filter dryer

If liquid line is sweating there is _____________________________________ .

350-450

Generally accepted range for evaporator airflow CFM per ton is __________________________ CFM

CFM

BTU/1.08x DeltaT

CFM

Cubic feet per minute______________

CFM

Temp rise method for determining air flow is _________

50

Recommended residential indoor relative humidity for summer is _____ %

lower higher

An inefficient compressor is indicated by __________ than normal head pressure _________ than normal suction pressure

high head pressure

A hermetic system that is low on refrigerant will not have

32

Frost on suction line indicates it's below dewpoint temp and below ______ degrees F

More

Increase in head pressure causes _______ refrigerant to flow through capillary tube.

Valve

With auto expansion valve an increase in evaporator load will cause the _________ to close

Low head pressure

When a TEV or capillary tube is used as a metering device low refrigerant charge will cause _________ ____________ __________________.

15

Max oporating pressure setting for an acetylene torch is _____ psig

45

When connecting copper to steel braise with ______ % silver alloy

flushing filter dryers

Solid contaminants from a hermetic compressor burnout are best removed by _____________ the system and installing _______ /_______ in both the liquid and suction lines

reduce

If the cut off plate is removed from blower assembly, it will ___________ air flow

Inert gas

Can use a trace amount of refrigerant and __________ ______ to leak test the system

low

After properly recharging a system, if the compressor is noisy, it is _____ on oil

inefficient

Over sized air conditioning system can cause _________________ de-humidification of the space

low

Low operating pressure and low system amperage draw causes _______ air flow across the evaporator

high

Air or other non-condensables will cause ______ suction line and ________ discharge line pressure

high

Refrigerant overcharge will cause _______ suction and _______discharge pressure

high low

Compressor with broken reed valve causes _______ suction and ________ discharge pressure