CM 411 Midterm #2

C. transformer

A ___ is an electric device that uses electromagnetism to chance AC voltage from one level to another. A. thermostat B. relay C. transformer D. circuit breaker

D. all of the above

A ____ is an example of a physical arrangement for air conditioning systems. A. split system B. packaged unit C. combination unit D. all of the above

D. reversing valve

A capillary tube runs from the pilot valve cylinder to the suction line on the___. A. refrigerant line B. bypass circuit C. compressor D. reversing valve

C. enthalpy

A change in both dry bulb and wet bulb temperatures affects______ . A. the specific volume in the air B. latent heat ratio C. enthalpy D. none of the above

B. outlet piping

A flow control valve is located on the____of a boiler. A. inlet piping B. outlet piping C. water outlet D. water inlet

D. burner

A fuel oil___ is a boiler component that provides atomized fuel oil to the boiler. A. strainer B. gas valve C. pump D. burner

C. 1/7000

A grain is the unit of measure that equals_____ lb. A. 1/70 B. 1/700 C. 1/7000 D. 1/70000

C. 120

A hot surface igniter has a current that is usually _____VAC. A. 100 B. 110 C. 120 D. 130

C. oil

A refrigerant should be miscible with_____ A. water B. air C. oil D. heat

C. four

A reversing valve consists of a piston and a cylinder that have___refrigerant line connections. A. two B. three C. four D. five

C. 12,000

A ton of cooling is equal to____ Btu/hr. A. 12 B. 1200 C. 12,000 D. 120,000

B. chiller

A(n) ____ is the component in a hydronic air conditioning system that cools water, which cools the air. A. air conditioner B. chiller C. evaporating medium D. condensing medium

B. compound

A(n)-----gauge is a pressure gauge that indicates vacuum in inches of mercury and pressure in psi on the same gauge. A. steam pressure B. compound C. pressure-temperature D. operating

A. firetube

A-----boiler heats water that surrounds the fire tubes as the hot gases of combustion pass through the tubes. A. firetube B. watertube C. cast iron D. steel

A. fusible plug

A-----is a warning device used to indicate extreme overheating of the boiler from a low water condition. A. fusible plug B. vent valve C. bottom blowdown valve D. fitting

A. heat pump thermostat

A_ __ is a component that incorporates a system switch, heating thermostat, and cooling thermostat. A. heat pump thermostat B. multibulb thermostat C. multistage thermostat D. none of the above

C. transformer

A___ changes line voltage to low voltage in control systems. A. relay B. thermostat C. transformer D. circuit breaker

A. cabinet air conditioner

A___ holds a water coil, blower, and filter. A. cabinet air conditioner B. unit air conditioner C. forced-air air conditioner D. hydronic air conditioner

A. hot surface

A___ igniter uses a small piece of silicon carbide that glows when electric current passes through it. A. hot surface B. silicon C. glow plug D. furnace

D. dehumidifier

A___ is a device that removes moisture from air by causing moisture to condensation A. ventilation system B. filter C. humidifier D. dehumidifier

B. unit ventilator

A___ is a forced convection heater that has a blower, hot water coil, filters, controls, and a cabinet that has an opening for outdoor ventilation. A. cabinet heater B. unit ventilator C. unit heater D. cabinet convector

C. distribution system

A___ is not a component of a furnace. A. cabinet B. heat exchanger C. distribution system D. filter

D. feedwater

A___ valve controls the flow of makeup water into a boiler to compensate for losses. A. check B. gate C. safety D. feedwater

C. forward-curved

A____ centrifugal blower is furnished with a typical furnace. A. backward-curved B. vane-axial C. forward-curved D. propeller

A. cascade system

A_____is a compression system that uses one refrigeration system to cool the refrigerant in another system. A. cascade system B. two-stage compression system C. refrigerant property table D. none of the above

C. refrigerant control valve

A___is a combination expansion device and check valve. A. tapping valve B. thermostatic expansion valve C. refrigerant control valve D. solenoid-operated pilot valve

C. two-pipe direct-return piping system

A___is a piping system that circulates the supply water in the opposite direction of the circulation of the return water. A. one-pipe primary-secondary piping system B. one-pipe series piping system C. two-pipe direct-return piping system D. two-pipe reverse-return piping system

C. zone

A___is a specific section of a building that requires separate temperature control. A. combination unit B. rooftop unit C. zone D. packaged unit

C. globe

A___valve is a metering valve that controls the volume of gas sent to a burner. A. gas vent B. gas butterfly C. globe D. stop

B. large commercial or industrial applications

Absorption systems are used on____. A. small residential applications B. large commercial or industrial applications C. all applications D. none of the above

C. 75

Air enters a furnace at a dry bulb temperature of__°F and 50% relative humidity and leaves the furnace at a dry bulb temperature of 94°F. A. 25 B. 60 C. 75 D. 80

B. 15

Air temperature above____ °F works well as a heat sink. A. 10 B. 15 C. 20 D. 25

D. feet per minute

Air velocity is expressed in_____. A. gallons per hour B. feet per hour C. gallons per minute D. feet per minute

A. 50

Area of influence is the area from the front of a register to a point where the air velocity drops below___ fpm. A. 50 B. 75 C. 100 D. 500

B. two

At least_____disconnect(s) are located in the electrical power circuit to an air conditioning system. A. one B. two C. three D. four

B. 62.32

At standard conditions, water has a density of______lb/cu ft and a specific heat of 1.0 Btu/lb. A. 60.31 B. 62.32 C. 63.33 D. 64.32

C. both gas and oil

Atmospheric burners burn ____to produce heat. A. gas fuel B. fuel oil C. both gas and oil D. none of the above

B. hotter

Because the refrigerant absorbs heat from the compression process, the refrigerant that leaves the compressor is______than the refrigerant in the rest of the system. A. cooler B. hotter C. denser D. none of the above

B. combination units

Buildings dial require cooling in the summer and heating in the winter require ____________ A. package units B. combination units C. split systems D. none of the above

C. 50

Comfort is usually attained at normal cooling and heating temperatures with a relative humidity of about____%. A. 10 t B. 30 C. 50 D. 70

D. all of the above

Common reasons for poor indoor air quality in building spaces are______ . A. air pollutant sources B. poor ventilation C. unanticipated building uses D. all of the above

D. all of the above

Controls cycle the components of an air conditioning system ON and OFF to produce required refrigeration effect_____. A. safely B. consistently C. automatically D. all of the above

C. psychrometric charts

Engineers and air conditioning technicians use__ __ to define properties of moist air during processes that change the properties of air. A. hygrometers B. sling psychrometers C. psychrometric charts D. none of the above

A. 1; 2

For maximum comfort, temperature control equipment maintains air temperature in a building within____°F or___ °F of the temperature necessary of comfort. A. 1; 2 B. 2; 4 C. 3; 6 D. 5; 1

C. refrigerant vapor; cold

Heat flows from the hot__to the___ condensing medium operating refrigeration system. A. air; water B. air; oil C. refrigerant vapor; cold D. air; refrigerant vapor

C. psychrometer or hygrometer

Humidity can be measured with a------ • A. psychrometer B. hygrometer C. psychrometer or hygrometer D. none of the above

C. relative humidity or humidity ratio

Humidity is expressed as____ . A. relative humidity B. humidity ratio C. relative humidity or humidity ratio D. none of the above

B. decrease

If the dry bulb volume temperature decreases, the specific volume will--------- ■ A. increase B. decrease C. not change D. none of the above

D. try cocks

If the gauge glass is not functional, the second method for determining boiler water level is___. A. water hammer B. firetube boiler C. watertube boiler D. try cocks

C. pushrod

In a thermostatic expansion valve, a(n)___ connects the diaphragm in the top of the valve to a ball inside the valve body. A. piston B. orifice C. pushrod D. coil

D, solenoid

In a___ , an electromagnet positions a movable core that opens or closes a sei of contacts. A. relay B. transformer C. magnetic starter D. solenoid

B. two-pipe

In a____system, supply water flows into each terminal device from the supply pipe. A. one-pipe B. two-pipe C. three-pipe D. four-pipe

C. evaporator; refrigerant

In an absorption system, heat is transferred from the „______medium to the_____ in the evaporator. A. evaporator; circulating pump B. absorber; generator C. evaporator; refrigerant D. condenser; refrigerant

B. metering device

Low-pressure chillers normally use an orifice-type or a float-type________ . A. condenser B. metering device C. evaporator D. none of the above

C. inches

Minute pressure changes can be expressed in _____ of water column. A. pounds B. meters C. inches D. millimeters

B. 3.5

Most natural gas burners operate with a pressure of _____" WC. A. 0.1 B. 3.5 C. 10.5 D. 13.5

B. 0.03

On a chart for standard conditions, humidity ratio begins at 0 lb of moisture per pound of dry air and increases to about_____lb of moisture per pound of dry air. A. 0.003 B. 0.03 C. 0.30 D. 3.0

D. 29.92

One pound of dry air and its associated moisture at standard conditions has a pressure of____ Hg. A. 20.92 B. 22.92 C. 25.92 D. 29.92

C. chlorofluorocarbons

Refrigerants that use_____ are believe to be responsible for the depletion of the Earth's ozone layer and may cause global warming. A. halocarbons B. hydrofluorocarbons C. chlorofluorocarbons D. none of the above

B. water inlet

Return piping is connected to a centrifugal pump at the_____. A. water outlet B. water inlet C. flow control valve D. pressure-reducing valve

A. keep dust out

The cabinet of a furnace is used to_____ . A. keep dust out B. separate flue gas and air C. A and B D. none of the above

C. provides more heating surface

The heat exchanger in a combustion furnace primarily _______. A. separates flue gas and air B. allows heat transfer C. provides more heating surface D. provides space for excess flue gas

A. decrease

The liquid refrigerant passes through the orifice, causing a pressure________. A. decrease B. balance C. medium D. increase

A. increased

The maximum amount of natural draft can be___with the height of the chimney. A. increased B. decreased C. balanced D. none of the above

B. generator

The pressure increases more when the temperature increases because of heat added in the____. A. condenser B. generator C. Evaporator D. circulating pump

B. running out

The pressure of the atmosphere on the mercury in the open dish prevents mercury in the tube from___. A. evaporating B. running out C. vaporizing D. absorbing

C. final condition and initial condition

The properties of cool air are found by locating the_______ of air on the chart and identifying the appropriate properties of the air at each point. A. final condition B. initial condition C. final condition and initial condition D. none of the above

B. fluorine

The second digit in a two-digit refrigerant number represents the number of ______ atoms in each molecule of the refrigerant. A. hydrogen B. fluorine C. oxygen D. carbon

B. EXVs

The sensor for the____is a thermistor mounted in the liquid line from the evaporator to monitor the temperature of the refrigerant vapor. A. TXVs B. EXVs C. CFCs D. none of the above

D. NOWL

The surface blowdown line piping is located at the ________ of the boiler. A. cross tees B. isolation valve C. vent D. NOWL

B. pressure

The temperature of the refrigerant in an absorption refrigeration system is controlled by the____of the refrigerant in the evaporator and the condenser. A. vaporization B. pressure C. heat D. none of the above

A. size

The type, location, and_____of registers determine the amount of supply air that is introduced into each building space and the distribution pattern of the air. A. size B. cost C. style D. manufacturer

C. 55°F

The water returning to the chiller from the building is normally at a temperature of about____. A. 45°F B. 50°F C. 55°F D. none of the above

B. setback

Thermostat___ is the reduction in heating setpoint at night when occupants are asleep or the space is unoccupied. A. control B. setback C. adjustment D. tuning

C. anemometer

To measure the airflow to or from diffusers or grills where there is not enough room, a(n)____is used. A. balometer B. metering device C. anemometer D. none of the above

C. lithium bromide

Water and____ are often used as refrigerant and absorbent in small to medium-size absorption refrigeration systems. A. ammonia B. chlorine C. lithium bromide D. none of the above

B. moisture in the air

Wet bulb temperature readings indicate the amount of______ . A. humidity in the air B. moisture in the air C. sensible heat in the air D. none of the above

B. bypass circuit

When a capillary tube expansion device is used in a heat pump system, a_______ is normally installed around the capillary tube because the refrigerant must be filtered. A. refrigerant line B. bypass circuit C. reversing valve D. none of the above

B. indoor; outdoor

When a heat pump is in the cooling mode, the______unit is the evaporator and the ___unit is the condenser. A. outdoor; indoor B. indoor; outdoor C. both are indoor units D. both are outdoor units

D. air-to-air

When a(n)____heat pump operates in heating mode, the outdoor coil functions as an evaporator. A. water-to-air B. water-to-water C. air-to-water D. air-to-air

D. no

When moist air is heated, sensible heat is added and there is a________ change in humidity. A. 25% B. 50% C. 75% D. no

C. 265;80

When operating in the cooling mode, the heat pump has a high-pressure-side pressure of____psig and a low-pressure-side pressure of______psig. A. 70;255 B. 255;70 C. 265;80 D. 80;2

D. 1080

When the refrigerant leaves the evaporator, it is at a temperature of 41°F with a heat content of____Btu/lb. A. 1020 B. 1030 C. 1050 D. 1080

C. 10.5

While operating, most LP gas burners have a pressure of -------" WC. A. 0.1 B. 3.5 C. 10.5 D. 15.5

B. Heat exchangers

_ __ are often coated with corrosion-resistant ceramic glazing. A. Furnaces B. Heat exchangers C. Burners D. Blowers

B. Humidity

___ level is controlled by humidifiers and dehumidifiers. A. Circulation B. Humidity C. Ventilation D. Filtration

B. Medium

___-size air conditioners have cooling capacities of 1.5 tons to 7.5 tons ot cooling. A. Small B. Medium C. Large D. Extra large

B. Air

_____ is used as the condensing medium for an air conditioning system when the condenser can be located outdoors. A. Water B. Air C. Combination D. none of the above

C. Rotary screw

___compressors used in chillers are large capacity, positive-displacement compressors that have few moving parts. A. Scroll B. Reciprocating C. Rotary screw D. Centrifugal

D. all of the above

___directly relates to the amount of moisture in the air. A. Wet bulb temperature B. Humidity ratio C. Relative Humidity D. all of the above

C. Induced

___draft is a mechanical draft created by air pulled through the boiler firebox by a blower located in the breaching after the boiler. A. Natural B. Forced C. Induced D. Balanced

B. Forced

___draft is mechanical draft created by air pushed through the firebox by blowers located on the front of the boiler. A. Natural B. Forced C. Balanced D. Induced

A. Low-pressure chillers

___have a purge unit to remove "non-condensables" from the system. A. Low-pressure chillers B. High-pressure chillers C. Absorption chilled-water systems D. all of the above

A. Air-to-water

___heat pumps are used to heat and cool large buildings that use hydronic heating and cooling systems. A. Air-to-water B. Water-to~air C. Air-to-air D. Water-to-water

B. Fuel fired

___heaters are used when a heat pump is added to an existing heating system, allowing the indoor coil to be placed on the supply side of the furnace. A. Gas fuel B. Fuel fired C. Gas fuel or fuel fired D. none of the above

B. Dry bulb temperature

___is the measurement of sensible heat. A. Wet bulb temperature B. Dry bulb temperature C. Humidity ratio D. none of the above

B. Circulation

___is the movement of air. A. Ventilation B. Circulation C. Filtration D. none of the above

C. Initial condition

___is the point that represents the properties of air before it goes through a process. A. Final condition B. Standard condition C. Initial condition D. none of the above

A. Temperature stratification

___is the variation of air temperature in a building space that occurs when warm air rises to the ceiling and cold air drops to the floor. A. Temperature stratification B. Stagnant temperature C. Air quality D. Pollutant control

D. all of the above

___refrigerants contain carbon. A. MFCs B. HCFCs C. CFCs D. all of the above