HVAC 145
HVAC 145 GAS/HEAT PRACTICE FINAL
EXAM QUESTIONS AND ANSWERS
a gas valve with 100% shut off means: - Gas to a pilot and manifold is shut-off
A gas furnace has an electronic control board. How is the fan cycled during heating? -
time
A primary cause of burner "flashback" is: - Low manifold pressure
The reason for a crossover on a gas burner is to - Provide smooth lighting of all burners
A technician need to run thermostat wire 75 feet. To avoid a voltage drop, the technician
should use: - # 16 AWG
A gas furnace has an induced draft fan. Which switch must operate properly before
ignition sequence starts? - differential air pressure
You read 0 ohms between the common and low speed wires on a 120 VAC furnace motor.
You determine the winding is: - shorted
The ohmmeter reads infinity between the high and low speed wires on a 120 VAC
furnace motor. What does this indicate? - open
The "bonnet capacity" of a furnace is: - furnace output BTU's
HVAC 145
, HVAC 145
Gas furnaces installed at altitudes above ____ feet needs to have adjustments to operate
properly. - 2000
Failure to wire a replacement low voltage transformer in an electronic ignition furnace,
based on noted polarity, will: - cause flame rectification problems
A spark igniter operates at ____ VAC - 10,000 and higher
The pressure inside an induced draft heat exchanger for mid-effiency furnace is
approximately. - -.02"W.C.
A furnace specifies a temperature rise of 40 - 70 degrees. Temperature indicates a rise of
80 degrees. In response: - increase fan speed
A dedicated vent system: - Is the only vent for an appliance
Which of the following must be present for combustion to occur? - air, fuel, ignition
(heat)
Which of the following statements is true of nitrogen? - it reduces combustion efficiency
by absorbing heat.
Flashback indicates: - gas velocity is SLOWER than the speed at which the gas can burn.
An inclined manometer measurs; - pressures below 1" W.C.
Fan speed should be set by: - The temperature rise called for on the data plate
HVAC 145
HVAC 145 GAS/HEAT PRACTICE FINAL
EXAM QUESTIONS AND ANSWERS
a gas valve with 100% shut off means: - Gas to a pilot and manifold is shut-off
A gas furnace has an electronic control board. How is the fan cycled during heating? -
time
A primary cause of burner "flashback" is: - Low manifold pressure
The reason for a crossover on a gas burner is to - Provide smooth lighting of all burners
A technician need to run thermostat wire 75 feet. To avoid a voltage drop, the technician
should use: - # 16 AWG
A gas furnace has an induced draft fan. Which switch must operate properly before
ignition sequence starts? - differential air pressure
You read 0 ohms between the common and low speed wires on a 120 VAC furnace motor.
You determine the winding is: - shorted
The ohmmeter reads infinity between the high and low speed wires on a 120 VAC
furnace motor. What does this indicate? - open
The "bonnet capacity" of a furnace is: - furnace output BTU's
HVAC 145
, HVAC 145
Gas furnaces installed at altitudes above ____ feet needs to have adjustments to operate
properly. - 2000
Failure to wire a replacement low voltage transformer in an electronic ignition furnace,
based on noted polarity, will: - cause flame rectification problems
A spark igniter operates at ____ VAC - 10,000 and higher
The pressure inside an induced draft heat exchanger for mid-effiency furnace is
approximately. - -.02"W.C.
A furnace specifies a temperature rise of 40 - 70 degrees. Temperature indicates a rise of
80 degrees. In response: - increase fan speed
A dedicated vent system: - Is the only vent for an appliance
Which of the following must be present for combustion to occur? - air, fuel, ignition
(heat)
Which of the following statements is true of nitrogen? - it reduces combustion efficiency
by absorbing heat.
Flashback indicates: - gas velocity is SLOWER than the speed at which the gas can burn.
An inclined manometer measurs; - pressures below 1" W.C.
Fan speed should be set by: - The temperature rise called for on the data plate
HVAC 145
