Mechanical Engineering Unit 51 To 60 Which Part Will Need Cleaned There Excessive Soot Buildup Chimney Connector Suction

231)

Which part will need to be cleaned if there is excessive soot buildup?

A)

Chimney connector

B)

Suction line

C)

Oil tank

D)

Bypass plug

Answer:

A

Explanation:

A)

B)

C)

D)

232)

How is mineral insulated (MI) heating cable used?

A)

Embedded in concrete for electric radiant floor heating

B)

To make the heating elements in baseboard electric heaters

C)

To supply the power wiring to all types of electric heaters

D)

In standard electric cords

Answer:

A

Explanation:

A)

B)

C)

D)

233)

Which type of space heater must be turned on and operating when the space temperature falls

below freezing?

A)

Kerosene space heaters

B)

Gas space heaters

C)

Steam space heaters

D)

Electric space heaters

Answer:

C

Explanation:

A)

B)

C)

D)

234)

A catalytic space heater differs from other types of gas space heaters in that a catalytic space

heater:

A)

Has no flame.

B)

Does not require a steady supply of gas during operation.

C)

Condenses water out of the combustion gases.

D)

Has no vent.

Answer:

A

Explanation:

A)

B)

C)

D)

61

235)

What is the most frequently used type of electric space heater for residential and commercial

buildings?

A)

Suspended forced air heaters

B)

Infrared electric heaters

C)

Convection baseboard electrical heaters

D)

Cabinet–style electric heaters

Answer:

C

Explanation:

A)

B)

C)

D)

236)

Kerosene space heaters use:

A)

White gasoline.

B)

Number 2 fuel oil.

C)

Number 6 fuel oil.

D)

Number 1 fuel oil.

Answer:

D

Explanation:

A)

B)

C)

D)

237)

What are the two general categories of humidifiers?

A)

Condensing and noncondensing

B)

Packaged and split system

C)

Wet and dry

D)

Those that rely on heated air and those that supply their own energy to evaporate water

Answer:

D

Explanation:

A)

B)

C)

D)

238)

Which type of humidifier requires the least cleaning?

A)

Motorized atomizing humidifiers

B)

Bypass evaporative humidifiers, which do not hold water in a sump

C)

Wetted–element humidifiers that have a water sump

D)

Plate–type humidifiers

Answer:

B

Explanation:

A)

B)

C)

D)

62

239)

What type of humidifier has air flow from the supply plenum, through the humidifier, and into

the return plenum?

A)

A bypass humidifier

B)

A steam humidifier

C)

A vaporizing humidifier

D)

An atomizing humidifier

Answer:

A

Explanation:

A)

B)

C)

D)

240)

Which type of humidifier needs to be cleaned more than once a year?

A)

Steam

B)

Evaporative

C)

Vaporizing

D)

Atomizing

Answer:

C

Explanation:

A)

B)

C)

D)

241)

What controls the indoor blower motor on an 80 percent induced–draft furnace?

A)

The fan relay

B)

The thermostat

C)

The integrated furnace control board

D)

The fan switch

Answer:

C

Explanation:

A)

B)

C)

D)

242)

The two most common categories of gas–fired furnaces are:

A)

Category III and Category IV.

B)

Category I and Category IV.

C)

Category I and Category II.

D)

Category II and Category III.

Answer:

B

Explanation:

A)

B)

C)

D)

63

243)

How does air flow in a standing–pilot, natural–draft system?

A)

It relies on heat to decrease the convection of the air to pull air into the combustion chamber

and force flue gases into the proper vent.

B)

It relies on heat to pull air into the combustion chamber and a fan to remove flue gases.

C)

It relies on a fan to pull the air into the combustion chamber and blow flue gases out.

D)

It relies on heat to increase the buoyancy of the air to pull air into the combustion chamber

and force flue gases into the proper vent.

Answer:

D

Explanation:

A)

B)

C)

D)

244)

How is a concentric vent used in a high–efficiency furnace?

A)

It allows a single outdoor exit point for the vent and combustion air pipe.

B)

It allows the vent pipe to combine with condensate drainage.

C)

It creates two close exit points for the vent pipe and combustion air pipe.

D)

It directs the combustion air pipe to an outdoor exit.

Answer:

A

Explanation:

A)

B)

C)

D)

245)

Which of the following is TRUE of the fan switch?

A)

The fan switch is not separate from the burner.

B)

The fan switch relies on a temperature cycle in modern furnaces.

C)

Modern fan switches cycle the fan based on time.

D)

The fan switch starts the blower when the burner starts.

Answer:

C

Explanation:

A)

B)

C)

D)

64

246)

The operating sequence to light the main burners on an intermittent pilot system is:

A)

The pilot valve and spark igniter are energized, the pilot flame is proved, and then the main

gas valve is energized.

B)

The main valve is energized, than the spark igniter, and finally the pilot valve.

C)

The main valve and spark igniter are energized, the pilot flame is proved, and then the pilot

gas valve is energized.

D)

The pilot valve and main valve are energized simultaneously.

Answer:

A

Explanation:

A)

B)

C)

D)

247)

The burner assembly and furnace cabinet should be grounded for safety and because:

A)

The induced draft fan motor will not operate unless the unit is grounded.

B)

Most control boards for direct spark ignition or hot surface igniters will not operate

correctly unless the unit is grounded.

C)

The indoor blower motor will not operate unless the unit is grounded.

D)

The transformer will not operate unless the unit is grounded.

Answer:

B

Explanation:

A)

B)

C)

D)

248)

What is the usual setting for the limit on the fan/limit switch of a warm air furnace?

A)

180°F to 200°F

B)

120°F to 150°F

C)

250°F to 300°F

D)

80°F to 100°F

Answer:

A

Explanation:

A)

B)

C)

D)

249)

How does the presence of 7 to 9 percent CO2 in flue gas reflect heating unit performance?

A)

It indicates a lack of efficiency.

B)

It indicates that the unit is running efficiently.

C)

It indicates a possible gas leak.

D)

It indicates the level of CO2 is neutral.

Answer:

B

Explanation:

A)

B)

C)

D)

65

250)

What size should the combustion air openings be for a room with an 80,000 BTU/hr input furnace

and a 35,000 BTU/hr water heater if the openings are opening directly into a ventilated attic and a

ventilated crawlspace?

A)

115,000/2,000 = 57.5 sq in free area each

B)

The size is irrelevant so long as there are combustion air vents.

C)

115,000/4,000 = 28.75 sq in free area each

D)

115,000/1,000 = 115 sq in free area each

Answer:

C

Explanation:

A)

B)

C)

D)

251)

How do technicians adjust inshot burners in high–efficiency furnaces?

A)

Timers are adjusted.

B)

Gas pressure only is adjusted.

C)

Airflow only is modified.

D)

Combustion speed is slowed.

Answer:

B

Explanation:

A)

B)

C)

D)

252)

To resist corrosion, the recuperative cell on a condensing oil furnace is made of:

A)

Teflon–coated steel.

B)

Aluminized steel.

C)

High–quality stainless steel.

D)

Heavy galvanized steel.

Answer:

C

Explanation:

A)

B)

C)

D)

253)

Why can oil furnaces operate at higher efficiencies than gas furnaces without condensing water in

the heat exchanger or vent?

A)

Unlike gas, no water is mixed with the oil during the combustion process.

B)

Oil furnaces burn hotter.

C)

The flue gas contains only half as much water as flue gas from a gas furnace.

D)

Oil furnace heat exchangers are inherently more efficient.

Answer:

C

Explanation:

A)

B)

C)

D)

66

254)

What is a residual oil?

A)

Residuals are bio–fuels manufactured from ethanol.

B)

Residuals evaporate at relatively low temperatures.

C)

Residuals are filtered to remove impurities.

D)

A residual is what is left after all the distillates have been vaporized.

Answer:

D

Explanation:

A)

B)

C)

D)

255)

What components on an oil furnace should be changed annually?

A)

The fuel–line filter, nozzle, and electrodes

B)

The fuel–line filter, nozzle, ignition transformer, and electrodes

C)

The fuel–line filter

D)

The fuel–line filter and the nozzle

Answer:

D

Explanation:

A)

B)

C)

D)

256)

When checking combustion efficiency, which measurement should be taken first?

A)

Smoke

B)

Stack temperature

C)

Oxygen

D)

Draft

Answer:

B

Explanation:

A)

B)

C)

D)

257)

Combustion with a perfect stoichiometric mix of oil and air produces a vent gas CO2 percentage

of:

A)

12.5 percent.

B)

9.5 percent.

C)

10.5 percent.

D)

15.5 percent.

Answer:

D

Explanation:

A)

B)

C)

D)

67

258)

What is the difference between bonnet capacity and firing rate?

A)

They are essentially the same thing–the amount of heat consumed.

B)

Firing rate is the amount of heat consumed while bonnet capacity is the amount of heat

delivered.

C)

They are essentially the same thing–the amount of heat delivered.

D)

Bonnet capacity is the amount of heat consumed while firing rate is the amount of heat

delivered.

Answer:

B

Explanation:

A)

B)

C)

D)

259)

Before starting an oil furnace, the technician should check to see that:

A)

The flame–observation door and all clean–outs are open.

B)

The flame–observation door is open for viewing.

C)

The flame–observation door and all clean–outs are closed.

D)

The clean–out doors are open to allow unwanted debris to be blown out during ignition.

Answer:

C

Explanation:

A)

B)

C)

D)

260)

What causes soot buildup in the heat exchanger and vent?

A)

Soot buildup is caused by using high–carbon fuel oil.

B)

Soot buildup is caused by incomplete combustion.

C)

Soot buildup is caused by low indoor air flow.

D)

Soot buildup is a normal consequence of any combustion process.

Answer:

B

Explanation:

A)

B)

C)

D)

261)

When the burner shuts off, the pump output pressure drops below 80 psig. This indicates:

A)

That the oil pump has a leaky shutoff.

B)

Correct operation.

C)

That the oil nozzle needs changing.

D)

That the oil filter is clogged.

Answer:

A

Explanation:

A)

B)

C)

D)

68

262)

What is the main safety concern for any type of gas–fired room heater?

A)

The space where they are installed must have sufficient infiltration to supply the necessary

combustion air.

B)

The electrical wiring to the unit must be heavy gauge to accommodate a high current draw.

C)

They will overheat if the ductwork is undersized.

D)

They are dangerous if used as a drying rack for wet clothing.

Answer:

A

Explanation:

A)

B)

C)

D)

263)

The standard wattage rating of electric baseboard heaters is:

A)

150 W per foot.

B)

250 W per foot.

C)

100 W per foot.

D)

200 W per foot.

Answer:

B

Explanation:

A)

B)

C)

D)

264)

The ideal range of relative humidity for promoting health is:

A)

50 to 70 percent.

B)

10 to 20 percent.

C)

30 to 60 percent.

D)

75 to 100 percent.

Answer:

C

Explanation:

A)

B)

C)

D)

265)

Which of the following is the optimum percentage of relative humidity?

A)

2040 percent

B)

2550 percent

C)

3060 percent

D)

5075 percent

Answer:

C

Explanation:

A)

B)

C)

D)

69

266)

How long is an ignition trial on a direct spark ignition system?

A)

1 minute to 2 minutes

B)

30 seconds to 1 minute

C)

4 to 21 seconds

D)

30 minutes

Answer:

C

Explanation:

A)

B)

C)

D)

267)

Gas valves for an intermittent pilot system:

A)

Have a pulsing LED that indicates valve activity.

B)

Have both a pilot valve and a main valve.

C)

Are the same as traditional combination gas valves.

D)

Have a single gas outlet that switches between the pilot light and the main burners.

Answer:

B

Explanation:

A)

B)

C)

D)

268)

What measurements are required to check combustion efficiency?

A)

Return air temperature, supply and temperature, and stack temperature

B)

Manifold pressure, firing rate, and gas heating value

C)

O2%, CO2%, and CO ppm

D)

Ambient temperature, stack temperature, flue gas O2%, and flue gas CO%

Answer:

D

Explanation:

A)

B)

C)

D)

269)

The grade of fuel oil most commonly used in residential oil–fired furnaces is:

A)

Number 5.

B)

Number 2.

C)

Number 6.

D)

Number 1.

Answer:

B

Explanation:

A)

B)

C)

D)

70

270)

The first check when answering a no–heat oil furnace call should be:

A)

Checking the output of the ignition transformer.

B)

Checking to see if there is oil in the tank and if the oil is clean.

C)

Checking the cad cell circuit.

D)

Checking the fan switch setting.

Answer:

B

Explanation:

A)

B)

C)

D)

271)

The application of electric space heaters is generally more flexible than space heaters that rely on

combustion because:

A)

They do not require any combustion air and do not require venting.

B)

They can be located anywhere in the room with a long extension cord.

C)

No clearance to combustible materials is required; they have no flames.

D)

They can be operated on batteries.

Answer:

A

Explanation:

A)

B)

C)

D)

272)

The most common sensing materials used in mechanical humidistats are:

A)

Nylon strips and hair.

B)

Bimetal strips and Bourdon tubes.

C)

Charged bulb and expansible tube.

D)

Diaphragm and bellows.

Answer:

A

Explanation:

A)

B)

C)

D)

273)

The ignition operating sequence and flame safety are controlled on an oil burner by:

A)

The combination oil valve and thermocouple.

B)

The ignition transformer and oil burner.

C)

The thermostat and limit switch.

D)

The primary control.

Answer:

D

Explanation:

A)

B)

C)

D)

71