L4 Home work

staged condenser

A P-T chart is used for refrigerant charge checks on systems.

0

A certified recovery refrigerant from a system containing 12 pounds of HCFC-22 refrigerant must be capable of evacuating the system to in. Hg vacuum.

reciprocating!

A compressor with a piston that travels back and forth in a cylinder is a compressor.

conditioned air is discharged into the conditioned space by the indoor directly unit

A ductless system is one in which

from a higher pressure to a lower pressure

A gas or liquid always flows

temperature glide

A range of temperatures in which a zeotrope refrigerant will evaporate and condense for a given pressure is called

low-temperature

A refrigerated fixture that is designed to operate at an evaporator temperature below -30°F would be classified as a application.

regulate and/or protect the cycle

A secondary control is used to

12,000 Btus per hour

A ton of refrigeration is equal to

90 minutes for 10 minutes

A usual frequency and duration for a defrost cycle is every

perform a leak check

After repairing a gas furnace, always

several minutes

After the application of a commercial bubble solution, a small leak take to may form a bubble.

a salt solution

All of the following may be used to check a furnace heat exchanger for leaks except

compressor current draw check

All of the following preventive mainte- nance procedures are unique to heat pumps except the

condensation

All superheat must be removed from a refrigerant before the of can process begin.

False

An effective method of testing a gas valve is to jumper the gas valve coil terminals to see if the gas valve closes.

recovered

Because of the Clean Air Act Amendments, all CFC, HCFC, and HFC refrigerants must be

drain and replace the compressor oil

Before using a recovery unit to process a different refrigerant than the last one used, should you

low-pressure switch

Bypass timers are often used to bypass the during startup.

receiver, sight glass/moisture indicator, filter-drier

Components (accessories) most often found in the refrigeration system liquid line are

picked up and thrown on to the condenser coil for re evaporation

Condensate from a refrigerated fixture can be

both moisture and air

Contaminants that may be found in a poorly maintained system are

for the lightest expected periods of usage

Defrost cycles should be programmed

there is a leak in the system

During a vacuum test, the vacuum gauge indicates a continuous pressure rise. This usually means

air flows in the same direction as in the cooling mode, and refrigerant flow re- verses

During the heating cycle of a heat pump,

are much easier to install than standard remote bulb thermostats

Electronic temperature controls generally

10 Btus

Five pounds of water heated to raise the temperature 2° requires

low refrigerant-to-air temperature difference

For perishable products requiring storage at high humidity levels, a unit cooler should be selected to operate with a(n).

high side of the system

Head pressure refers to the pressure in the

pitch in the direction of flow

Horizontal piping runs used in refrigeration systems should

manually with all ice removed

Ice merchandisers using cold-wall construc- tion are defrosted

by continuous contact with water for a specified period of time

Ice thickness sensors on cubed-ice machines function

boiling point is 72°F

If a gas is superheated 15° to a temperature of 87°F, we can determine that its

80°F

If a system is evacuated to a level of 25,400 microns, the liquid water in the system will boil at and above.

replaced at least once a year

If an electronic air cleaner contains a char- coal filter, the filter must be

adjust the primary air supply

If the gas flame in a natural gas furnace is yellow,

changing the blower speed

If the static pressure drop across a clean evaporator coil exceeds the manufacturer's recommendation, the problem should be corrected by

replace the nozzle

If there is a problem with the nozzle on an oil burner,

nothing flows over the outdoor coil

In a ground-source heat pump

condenser

In a refrigeration system, the high-pressure, high-temperature vapor is converted into a high-pressure, high-temperature liquid by the

evaporator

In a refrigeration system, the low-pressure, low-temperature liquid is converted into a low-pressure, low-temperature vapor by the

compressor

In a refrigeration system, the low-pressure, low-temperature vapor is converted into a high-pressure, high-temperature vapor by the

between zero and a trace

In a residential oil furnace burning No. 2 oil, the smoke reading should be

water is the heat source

In a water-to-air heat pump operating in the heating mode,

remain at the same temperature

In the condenser, the refrigerant liquid and vapor mixture will until all of the vapor has condensed to a liquid.

Defrost thermostat

Once the fan switch has been closed, what other device controls power to the evapora- tor fans?

True

One indication of inefficient combustion in furnace is the presence of soot.

operate at lower superheat values

One way to help compensate for the increased energy consumption in retail refrigeration systems, as compared to comfort cooling systems, is to

processed so that it meets the standards for new refrigerant

Reclamation of a refrigerant means that it is

removed from a system and stored in approved containers

Recovery of a refrigerant means that the refrigerant is

run through a cleaning and decontamination filtering device

Recycling of a refrigerant means that it is

requires two metering devices and two check valves

Refrigerant metering in a heat pump

can be sensed by a thermometer

Sensible heat is heat that

after all liquid has been changed to vapor

Superheat is added

superheat

TXV regulates the flow of refrigerant to the evaporator in order to maintain a constant

212°

The Fahrenheit scale is based on boiling water having a sea level temperature of

the pressure is decreased

The boiling temperature of a liquid will be lower as

500

The deep vacuum method of evacuation requires that the system be evacuated to a level of microns.

the fluorocarbon always has fluorine in it but not all halocarbons do

The difference between a halocarbon and fluorocarbon refrigerant is that

HFCS

The fluorocarbon refrigerants considered least harmful to the environment are the

suction side (input) of the compressor

The low side of the refrigeration system includes the

remove heat from the refrigerant

The main purpose of a condenser is to

add heat to the refrigerant

The main purpose of an evaporator is to

vacuum gauge

The most accurate way to measure vacuum is with a

room air temperature

The net stack temperature in an oil furnace is determined by subtracting the from the measured stack temperature.

capture liquid refrigerant to prevent compressor damage

The primary function of the suction accu- mulator is to

capillary tube

The refrigerant feed rate of the is con- trolled only by the refrigerant pressure applied.

HCFC-22, HFC-134a, and HFC-404A

The refrigerants that dominate the new equipment reach-in refrigeration market for medium- and low-temperature units are

refrigerant liquid at the expansion device

The subcooling charging method gives an indication of the amount of

the presence of measurable subcooling presence

The technician can determine if all the refrigerant in a condenser has changed to its liquid state by

near the center of the range specified by the manufacturer

The temperature rise in a natural fur- gas nace should be

a system that has two units, one indoors and the other outdoors

The term split system refers to

at least two flue pipe diameters from the furnace breeching

The test hole for checking furnace draft should be drilled

conduction

The transfer of heat from one object to another by direct contact is called

infrared electric heaters

To melt accumulated frost, do not require physical contact with the evapora- tor.

under pressure or in a vacuum

Ultrasonic leak detection can best be used to check systems

Gray with a yellow top

What is the color code for refrigerant recovery cylinders?

the compressor discharge is routed to the indoor coil

When a heat pump is in the reverse cycle heating mode,

superheat in the suction line

When charging by superheat, the outdoor and indoor temperatures are used to find the

both liquid and vapor refrigerant

When charging refrigerant by weight, you can charge with

230 psig

When charging using pressure charts, what is the required discharge line pressure if the suction pressure is 80 psig and the condenser entering air is 90°F? (Hint: Use the pressure chart in Figure 25.)

fractionation

When each of the refrigerants used in a blended refrigerant leak at a different rate if released into the atmosphere, changing the precise proportions of the refrigerants used in the blend, the process is called

An electric heater is cycled on to temper, or warm, the supply air.

When the unit is operating in the defrost mode, what usually happens in the condi- tioned space?

The SEER rating of the heat pump.

Which of the following is not determined from the balance point?

14.7 psi

Zero gauge pressure corresponds on the absolute scale to

insufficient flow through the metering device

low Allowing the head pressure to drop very due to low ambient conditions can cause

boil off or vaporize

of evacuating a system using a The purpose vacuum pump is to lower the system pressure so any moisture can

False

of the electric heater The primary purpose that comes on during the defrost mode of a heat pump is to melt the frost buildup on the coil.