HVAC CLASS 2336

Check valves that open insufficiently will

Act as a throttling device and create a pressure drop

A liquid line filter-drier needs to be replaced when ____

Both A and B

Bubbles in a sight glass may indicate ___

Both A and B

On heat pumps, each bypass line around a metering device usually contains a ___

Check valve

A valve with an adjustable pressure setting that prevents compressor inlet pressure from exceeding a preset safe value is a ____

Crankcase pressure regulator

A port containing a color-changing element used to indicate a system's moisture content is referred to as a moisture valve

False

A relief valve that consists of a metal core that melts at a much lower temperature than its outer shell is called a spring-loaded relief valve

False

Which of the following statements regarding off-cycle defrost systems is false?

It can only be used in very-low temperature systems.

The condenser pressure regulator closes when condenser pressure is

Less than the pressure exerted by the regulators adjustable spring

A single-body, combination condenser-receiver pressure regulator that regulates both condenser and liquid receiver pressures is a ___ control

Low-ambient

In what type of defrost system is air from the conditioned space circulated over the evaporator when the compressor is not running?

Off-cycle defrost system

Receiver pressure regulators

Open on a rise in pressure difference between a discharge line and a liquid receiver

Condenser pressure regulators and receiver pressure regulators are primarily use to ___

Raise high-side pressure

A condensate pump is used to ___

Remove the moisture that builds up from defrosting and condensation

After a compressor burnout, temporarily install a new ____ to protect the compressor for the duration of the cleanup

Suction line filter drier

After a compressor burnout, temporarily install a new ___ to protect the compressor for the duration of the cleanup

Suction line filter- drier

The color-changing element in a moisture indicator is designed to change color based on ___

The amount of moisture in the refrigerant

A small viewport installed in a refrigerant line is a sight glass

True

shutoff valves are designed so that they can be operated by hand

True

some commercial refrigeration applications require that water be kept from freezing at temperatures below 32F (0C)

True

A condenser that uses only the air movement of either natural convection or forced drafts to remove heat from a system's refrigerant is a(n) ___ condenser

air-cooled

In a nonfreezing solution defrost system, ___

all of the above

Solenoid valves are controlled by ___

an electric signal

surfaces in and along air ducts that direct airflow through the evaporator and throughout the cabinet are called

baffles

Valves that are used to permit flow in only one direction are ___

check valves

Valves that are used to permit fluid flow in only one direction are ___

check valves

Refrigerant line valves on a commercial refrigeration system ___

control the flow of refrigerant through system piping

A valve used to direct liquid refrigerant from the liquid line to combine with hot gas and provide a cooler refrigerant mixture into the low side is a ___

crankcase pressure regulator

an electric heat defrost system ___

energizes electric heating coils

A relief valve that consists of a metal core that melts at a much lower temperature than its outer sell is called a spring-loaded relief valve.

false

An off-cycle defrost system can only be used if the air in the conditioned space remains within five degrees of freezing

false

Relief valves should only be inspected every six to twelve years

false

Valves that enable technicians to access a system to add refrigerant, take pressure measurements, and perform other procedures are called check valves.

false

Heat exchangers featuring metal fins of various styles and types connected to evaporator tubing are ___ evaporators.

find-and tube

The condenser pressure regulator and receiver pressure regulator work together to maintain head pressure on the ___

high side of the system in low outdoor temperatures

page 17

left of

A single-body, combination condenser-receiver pressure regulator that regulates both condenser and liquid receiver pressure is a ___ control

low-ambient

An evaporator that depends on gravity for air circulation is a ___ evaporator

natural-draft

an evaporator that depends on gravity for air circulation is a ___ evaporator

natural-draft

In what type of defrost system is hot refrigerant gas diverted to the evaporator to expedite the defrosting process?

off-cycle defrost system

Heat exchangers made from two metal sheets that are welded together to form a series of passages are ___ evaporators.

plate

heat exchangers made from two metal sheets that are welded together to form a series of passages are ___ evaporators

plate

Relief valves are installed in a refrigeration system to

prevent equipment damage or personal injury by venting refrigerant

Relief valves are installed in a refrigeration system to ___

prevent equipment damage or personal injury by venting refrigerant

Condenser splitting is a method of head pressure control that makes use of ___

reduced volume

condenser splitting is a method of head pressure control that makes use of ___

reduced volume

A condensate pump is used to ___

remove the moisture that builds up from defrosting and condensation

A condenser in which a water tubing winds around the inside of a metal refrigerant shell is called a(m) ___ condenser.

shell-and-coil

A suction line-liquid line heat exchanger ___

superheats vapor refrigerant in the suction line

A suction line-liquid line heat exchanger ___.

superheats vapor refrigerant in the suction line

some type of water-cooled condensers use ___

the bottom part of the shell as a liquid receiver

A defrost timer that turns on defrost operations at a preset time and stops defrosting operations when the evaporator reaches a preset cut-out temperature is a ___ defrost timer

time-initiated, temperature-terminated

A defrost timer that turns on defrost operations at a preset time and ends the defrost operation at a preset time is a ___ defrost timer.

time-initiated, time-terminated

A riser is a length of horizontal refrigerant line

true

A rupture disc consists of a thin metal disc that bursts before the pressure in a system reaches dangerous levels

true

a sweet water bath is composed of 20% glycol and 80% tap water

true

air-cooling evaporators are used to directly cool the air within a conditioned space

true

closing the condenser housing louvers can be used to raise low head pressure in low ambient temperatures

true

some water defrost systems spray a lithium chloride brine solution over the evaporator

true

A liquid-cooling evaporator ___

uses a cooled liquid that acts as the primary heat transfer medium

In a hot-gas defrost system, the evaporator is defrosted by ___

warm liquid refrigerant from the high side

which of the following statements regarding water defrost systems is false

water delivery may be done during a cooling cycle with the compressor running

In a tube-within-a-tube condenser, ___

water enters the condenser at the point where the liquid refrigerant exits

A condenser that uses only water as the medium into which system heat is expelled is a(n) ___ condenser.

water-cooled