Since 1992, the United States Department of Energy has required that all furnaces sold and installed from that date on must have an AFUE of no less
... [Show More] than:
A: 70%
B: 75%
C: 78%
D: 80%
C: 78%
Many pre-1992 furnaces have efficiencies around _______.
A: 10%
B: 40%
C: 60%
D: 80%
C: 60%
Today, furnaces with AFUE ratings greater than _____ are available.
A: 85%
B: 90%
C: 100%
D: 110%
B: 90%
A thermocouple is used with:
A: Intermittent pilot systems
B: Direct spark ignition systems
C: Glow coil ignition systems
D: Standing pilot ignition systems
D: Standing pilot ignition systems
The purpose of the gas pressure regulator is to:
A: Keep the color of the flame constant
B: Keep the high limit switch from tripping
C: Maintain a constant gas pressure at the burner
D: Allow the gas valve to operate smoothly and accurately
C: Maintain a constant gas pressure at the burner
The instrument used to measure outlet gas pressure is the:
A: Velometer
B: Anemometer
C: Monometer
D: Draft gauge
C: Monometer
The regulator on a natural gas furnace should be adjusted to supply _____ inches of pressure at the burners.
A: 11"
B: 10"
C: 3.5"
D: 2"
C: 3.5"
Burning one cubic foot of natural gas releases approximately _____ btu.
A: 800
B: 1,050
C: 12,000
D: 15,000
B: 1,050
Under ideal conditions natural gas has an ignition temperature of _______ degrees F and a burning temperature of ________ degrees F.
A: 800 degrees, 1000 degrees
B: 1,100 degrees, 3,500 degrees
C: 1,100 degrees, 5,000 degrees
D: 2,500 degrees, 8,000 degrees
B: 1,100 degrees, 3,500 degrees
Propane and butane are both:
A: Lighter than air
B: Heavier than air
C: Weigh the same as air
D: None of the above
B: Heavier than air
In order to achieve complete combustion with natural gas, each cubic foot of gas must combine with no less than ______ cubic feet of air with an additional 5 cubic feet of extra air to ensure there is enough oxygen for complete combustion.
A: 5 cubic feet
B: 10 cubic feet
C: 15 cubic feet
D: 20 cubic feet
B: 10 cubic feet
The three elements of combustion are:
A: Fuel, oxygen and ignition
B: Nitrogen, oxygen and heat
C: Air, fuel and oxygen
D: Air, fuel and nitrogen
A: Fuel, oxygen and ignition
Which of the following is a natural result of combustion?
A: Water vapor
B: Carbon monoxide
C: Carbon dioxide
D: All of the above
A: Water vapor
Primary air is air that:
A: Is mixed with the fuel before the fuel reaches the burner
B: Is mixed with the fuel at the burner after the fuel has ignited
C: Remains unused after the combustion process is complete
D: Enters the draft diverter and goes up the stack with the products of combustion
A: Is mixed with the fuel before the fuel reaches the burner
Secondary air is air that:
A: Is mixed with the fuel before the fuel reaches the burner
B: Is mixed with the fuel at the burner after the fuel has ignited
C: Remains unused after the combustion process is complete
D: Enters the draft diverter and goes up the stack with the products of combustion
B: Is mixed with the fuel at the burner after the fuel has ignited
The three major furnace configurations are:
A: Up-flow, down-flow and lowboy
B: Up-flow, down-flow and horizontal
C: Up-flow, down-flow and cross-flow
D: None of these is correct
B: Up-flow, down-flow and horizontal
Residential gas furnaces use blowers powered by which types of motors?
A: Poly-phase, two phase, single phase and capacitor start
B: Shaded pole, split-phase, capacitor start and PSC
C: Three phase, shaded pole and PSC
D: Split-phase, induction start-induction run and variable speed DC
D: Split-phase, induction start-induction run and variable speed DC
The horsepower range of residential heating blower motors is:
A: 1⁄8 to 1⁄16 hp
B: 1⁄4 to 1⁄2 hp
C: 1⁄2 to 2 hp
D: 3⁄4 to 2 hp
B: 1⁄4 to 1⁄2 hp
A heat anticipator is wired:
A: In series with the "W" terminal
B: In parallel with the "W" terminal
C: In series with the "R" terminal
D: In parallel with the "R" terminal
A: In series with the "W" terminal
Placing a jumper wire between the "R" terminal and the "G" terminal on a thermostat subbase will energize the:
A: Gas valve
B: Indoor fan motor
C: Outdoor fan motor
D: Compressor
B: Indoor fan motor
Placing a jumper wire between the "R" terminal and the "W" terminal on a thermostat sub-base will energize the:
A: Gas valve
B: Indoor fan motor
C: Outdoor fan motor
D: Compressor
A: Gas valve
Carbon monoxide is a:
A: Product of incomplete combustion
B: Poisonous gas
C: Odorless gas
D: All of the above are correct
D: All of the above are correct
The chemical symbol for carbon monoxide is:
A: CO2
B: CO
C: H2O
D: NH3
B: CO
Selecting a lower speed tap setting on a furnace indoor blower motor will cause:
A: The temperature rise through the furnace to increase
B: The temperature rise through the furnace to decrease
C: The temperature rise through the furnace will not be affected
D: The furnace to act as a humidifier
A: The temperature rise through the furnace to increase
"Carry over" channels or "cross overs" are used to:
A: Carry unused excess fuel back to the flue where it is sent up the stack
B: Carry primary air to the heat exchanger
C: Carry secondary air to the heat exchanger
D: Carry the flame from the first burner that lights to the remaining burners
D: Carry the flame from the first burner that lights to the remaining burners
Modern high-efficiency burners use combustion blowers. What are the two major types of combustion blowers?
A: Induced draft and forced draft
B: High pressure and low pressure
C: Impeller type and centrifugal type
D: Liquid and vapor types
A: Induced draft and forced draft [Show Less]