Rudy Robertson
Quiz von , erstellt am more than 1 year ago

This is practice for hell day on tuesday lol

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Rudy Robertson
Erstellt von Rudy Robertson vor fast 9 Jahre
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HVAC Practive midterm 56

Frage 1 von 56

1

On a standing pilot gas furnace the thermocouple must be replaced when?

Wähle eine der folgenden:

  • its not positioned properly

  • The millivolt reading is 28 or above

  • the millivolt reading is 22 or below

  • the tip of the thermocouple is in the tip if the pilot flame is 3/8

Erklärung

Frage 2 von 56

1

natural gas pressure at the main line is recorded at 7" WC (water column), But at the gas manifold it reads 1.5 WC. What is most likely to be the cause of this?

Wähle eine der folgenden:

  • A defective main line regulator

  • Too large of a gas valve

  • plugged burner orifices

  • A defective pressure regulator on the gas valve

Erklärung

Frage 3 von 56

1

A technician servicing a gas fired furnace notices that only four out of five ribbon burners are firing simultaneously . What could be the problem with the system?

Wähle eine der folgenden:

  • Too much gas pressure

  • Too little gas pressure

  • Burners not aligned correctly

  • A defective gas valve

Erklärung

Frage 4 von 56

1

Technician A says if a combination gas valve needs to be replaced if there are 24 volts present to the gas valve and it will not open.

Technician B says that if a combination gas valve has a new thermocouple and the pilot will not stay lit the gas valve needs to be replaced.

Which technician is correct?

Wähle eine der folgenden:

  • Tech A

  • TECH B

  • Both are right

  • Both are wrong

Erklärung

Frage 5 von 56

1

What should be the first step that a technician should take if the gas pressure at the manifold is too high?

Wähle eine der folgenden:

  • adjust the pressure regulator clockwise

  • adjust the pressure regulator counter clockwise

  • replace the pressure regulator

  • replace the combination gas valve

Erklärung

Frage 6 von 56

1

If the glame is lifting off the burner port what should the technician do to correct this problem?

Wähle eine der folgenden:

  • Adjust the primary air by closing the air shutter

  • adjust the primary air by opening the air shutter

  • replace the burner

  • decrease the min gas pressure.

Erklärung

Frage 7 von 56

1

a step down transformer is reading 0 ohms at its secondary winding. what is the possible cause of this problem?

Wähle eine der folgenden:

  • An open primary winding

  • an open secondary winding

  • A shorted primary winding

  • A shorter secondary winding

Erklärung

Frage 8 von 56

1

when a fan centre relay needs to be tested for 124 volts, what two terminals are used when measuring for transformer output voltages?

Wähle eine der folgenden:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R and "C'

Erklärung

Frage 9 von 56

1

On a call for heat what two terminals should be closed on the thermostat?

Wähle eine der folgenden:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R" and "C"

Erklärung

Frage 10 von 56

1

when a thermostat sub base fan selector switch is moved to the fan "ON" postition, what two terminals will close in the thermostat.

Wähle eine der folgenden:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R" and "C"

Erklärung

Frage 11 von 56

1

A new thermostat was recently replaced. The technician observes that the burner cycle is not long enough. the most likely cause would be?

Wähle eine der folgenden:

  • A defective thermostat

  • Low gas pressure

  • the anticipator needs adjusting

  • A defective gas valve

Erklärung

Frage 12 von 56

1

A customer has replaced a mercury bulb thermostat but complains that the burners will not shut off and the house is getting too hot. The cause would be?

Wähle eine der folgenden:

  • A defective limit control

  • A defective gas valve

  • The thermostat is not properly level

  • the anticipator is set too low

Erklärung

Frage 13 von 56

1

A bimetal fan control will not turn the indoor blower off. As a result cool air passes through the registers between furnace cycles. What is the possible cause of the problem.

Wähle eine der folgenden:

  • The heating circuit is open on limit.

  • the fan control contacts are stuck open

  • the fan control contacts are stuck closed

  • there is a defective gas valve

Erklärung

Frage 14 von 56

1

residents are complaining of experiencing sumptoms of headaches, watery eyes and nausea.

Tech A says the heat exchanger is cracked

Tech B says the furnace may only need cleaning and the heat exchanger is possibly plugged.

Whos correct?

Wähle eine der folgenden:

  • Tech A

  • Tech B

  • Both are correct

  • Both are incorrect

Erklärung

Frage 15 von 56

1

A belt driver motor has recently been replaced but the furnace is shutting off on limit control. the most likely cause is that .

Wähle eine der folgenden:

  • A. the motor is running in the wrong direction

  • the motor is defective

  • the motor is too large

  • the motor mount is not correct.

Erklärung

Frage 16 von 56

1

upon testing a motor winding for continuity the technician records 3 ohms. The winding resistance should be 8 Ohms. The technician concludes that:

Wähle eine der folgenden:

  • The winding is open

  • The winding is shorted

  • the winding is grounded

  • the motor is within the satisfactory operating conditions

Erklärung

Frage 17 von 56

1

A run capacitor is tested with an analog meter. The needle moves towards zero then back to infinity. What is the condition of the capacitor?

Wähle eine der folgenden:

  • The capacitor is open.

  • The capacitor is good

  • The capacitor should not be used

  • The capacitor needs to be of a higher mfd rating

Erklärung

Frage 18 von 56

1

The temperature rise of a particular furnace states that it should be between 35F and 65F. The furnace is operating at 20F temperature rise with the proper gas pressure at the manifold. What could be done to solve this problem.

Wähle eine der folgenden:

  • Add more outside air to the basement

  • increase the indoor blower motor speed

  • Decrease the indoor motor blower speed

  • replace the air filter with a more efficient type.

Erklärung

Frage 19 von 56

1

A belt driven motor has been replaces, but quickly gets hot and stops just short of burning out. Which of the following could cause the problem:

Wähle eine der folgenden:

  • A fan belt that is too tightly adjusted

  • A fan belt that has only 1" of slack between the pulleys

  • The pulley on the motor is too small

  • none of the above.

Erklärung

Frage 20 von 56

1

A combination fan/limit control has been replaced. The indoor blower motor runs too long and the residents complain of cooler airflow. The technician should:

Wähle eine der folgenden:

  • Replace the control again

  • Adjust the limit setting

  • Lengthen the fan off setting.

  • Check the readjust the fan-off differential

Erklärung

Frage 21 von 56

1

A service call is made to a customer who complains that when his furnace ignites, the flame rolls out in front of the head exchanger.

Technician A says that it is due to poor draft possibly a blocked flue or heat exchanger

Technician B says that it has to do with the limit control or the fan switch control circuit.

Wähle eine der folgenden:

  • Technician A

  • Technician B

  • Both Technician are correct

  • Both Technicians are incorrect

Erklärung

Frage 22 von 56

1

A customer complains of headaches, sleepiness and nausea.

Technician A finds a crack in the head exchanger and says that the furnace should be shut down.

Technician B says that the crack isnt too serious and the furnace can operate temporarily but it must be cleaned.

Wähle eine der folgenden:

  • Tech A is correct

  • Tech B is correct

  • Both technicians are correct

  • Both technicans are incorrect

Erklärung

Frage 23 von 56

1

A technician is servicing a standing pilot gas-fired furnace. The complaint is that the burners are not lighting. where should the technician start trouble shooting the system?

Wähle eine der folgenden:

  • At the transformer secondary and at the combination gas valve

  • At the transformer primary only.

  • At the primary limit control

  • at the fan limit controls.

Erklärung

Frage 24 von 56

1

On a spark ignition system, The spark for the ignition continues with no ignition of gas at the burners.

Technician A Concludes that the thermostat is defective.

Technician B Concludes that it is possibly the control module

Which is correct?

Wähle eine der folgenden:

  • Technician A

  • Technician B

  • Both are correct

  • Both technicians are incorrect

Erklärung

Frage 25 von 56

1

Which of the following is the correct test for a faulty cable on a direct spark ignition system?

Wähle eine der folgenden:

  • A voltage check

  • A continuity check

  • An amerpage check

  • none of the above

Erklärung

Frage 26 von 56

1

A customer complains that the burners light on her system, But then immediately shut down. The problem is most likely to be?

Wähle eine der folgenden:

  • In the control module

  • in the control transformer

  • in the limit control

  • in the gas valve

Erklärung

Frage 27 von 56

1

Which of the following would not be a proper procedure to perform on a direct spark ignition system where the spark continues, the burners light and the flames are immediately extinguished?

Wähle eine der folgenden:

  • Check that the sensor is positioned in the flame correctly

  • check for the proper flame rectification

  • check for a proper grounding terminal

  • check that there is proper gas flow to the pilot

Erklärung

Frage 28 von 56

1

A hot surface ignition system does not ignite the main burner. after measuring voltage to the igniter the technician should:

Wähle eine der folgenden:

  • Perform a resistance test on the igniter

  • Replace the flame sensor

  • Replace the main gas valve

  • Replace the control module

Erklärung

Frage 29 von 56

1

The burners of a gas furnace that is equipped with a 115-Volt hot surface igniter lights for approximately 7's and then goes out. what is the problem that could cause this symptom.

Wähle eine der folgenden:

  • A faulty igniter

  • A faulty transformer secondary winding

  • burner shutting off on high limit control

  • a faulty sensor

Erklärung

Frage 30 von 56

1

The burners on a furnace having a hot surface ignition system light up but quickly shut off.

Technician A states that after testing the gas valve he determined that it has shorter

Technician B Visually checked the flame sensor, cleaned it and performed a continuity test. he faults a dirty sensor.

Whos correct?

Wähle eine der folgenden:

  • Technician A

  • Technician B

  • Both Technicians are correct

  • Both technicians are incorrect

Erklärung

Frage 31 von 56

1

The thermostat on a mid efficiency gas furnace with a hot surface ignition system is placed on a call for heat. The burners do not light, but the igniter does glow. Which of the following would be the next step to take when troubleshooting the system?

Wähle eine der folgenden:

  • test the flame sensor

  • test the gas valve and the gas manifold pressure

  • test the primary limit control and the fan control

  • test the thermostat

Erklärung

Frage 32 von 56

1

The draft pressure switch on a mid effciency gas furnace with a hot surface ignition system is placed on a call for heat. the burners do not light, but the igniter does glow. Which of the following would be the next step to take when troubleshooting the system?

Wähle eine der folgenden:

  • Test the flame sensor

  • test the gas valve and the gas manifold pressure.

  • a defective inducer draft motor

  • a defective flame roll out sensor

Erklärung

Frage 33 von 56

1

A high efficiency gas furnace will not stay in operation. The unit runs for approximately 5 min then shuts down by the main furnace controller with an open pressure switch flash code. which of the following is not a proper test to perform in this situation?

Wähle eine der folgenden:

  • check the inducer draft motor

  • Check the furnace filter

  • Check for a restricted flue pipe

  • both a and c

Erklärung

Frage 34 von 56

1

A service call is made on a mid efficiency gas furnace. on a call for heat, the induced draft motor will not operate. what is the proper trouble shooting procedure that should be taken.

Wähle eine der folgenden:

  • Check for control voltage at "G" and "C" terminals at the circuit board.

  • check for control voltage across terminals "W" and "C" at the circuit board.

  • check the control voltage at the induced draft relay

  • Both B and C

Erklärung

Frage 35 von 56

1

A high efficiency gas furnace that uses a controller will not energize the blower motor after a pre selected 45sec time on setting. Which of the following would be the most correct trouble shooting procedure?

Wähle eine der folgenden:

  • measure the resistance across the furnace controller low speed terminal and common.

  • measure the resistance across the furnace controller high speed terminal and common

  • measure the voltage to the motor and test the run capacitor

  • measure the amperage on the blower motor and test the run capacitor.

Erklärung

Frage 36 von 56

1

when servicing a mid efficiency gas furnace the thermostat has been turned to the off position but the burners remain lit and the induced draft motor continues to operate. which of the following would be the most correct troubleshooting procedure?

Wähle eine der folgenden:

  • determine if the thermostat is open and check voltage at the gas valve

  • check for voltage at the indoor blower motor.

  • replace the control module

  • check the ignition system

Erklärung

Frage 37 von 56

1

on a high efficiency gas furnace that uses a controller the indoor blower motor will not de energize after its pre selected off delay setting. which of the following is a logical repair for the system.

Wähle eine der folgenden:

  • replace the run capacitor

  • replace the blower motor

  • replace the control module

  • change the speed setting on the control module

Erklärung

Frage 38 von 56

1

The burners on a gas furnace cycle for approximately 3 to 4 min. during a call for heat. the system does not provide adequate heat for the home.

Technician A has determind that a new thermostat has been installed and that the heat anticipator was incorectly adjusted

Technician B cleans the position of the flame sensor and claim that this was the fault

Whos correct?

Wähle eine der folgenden:

  • tech A

  • Tech B

  • both are correct

  • both are incorrect

Erklärung

Frage 39 von 56

1

A gas furnace has recently been converted to LP gas. on a call for heat the furnace is not firing correctly and is starting to soot up. what would be the most likely cause for this problem?

Wähle eine der folgenden:

  • Low LPG pressure

  • too long of a burner cycle

  • wrong orifice size installed

  • all of the above

Erklärung

Frage 40 von 56

1

when inspecting a gas furnace it is noticed that the burner flames are very small in height. what action should be taken by the technician?

Wähle eine der folgenden:

  • replace the gas valve

  • replace the orifices

  • check the pressure and adjust the primary air shutters if needed

  • contact the utility company to replace the gas meter

Erklärung

Frage 41 von 56

1

a customer is experiencing a loud delayed ignition from his gas furnace.

Tech A says its possible that the gas valve is not opening or closing properly

Tech B claims that its possible that after the furnace had been cleaned the burner were not properly aligned.

whos correct?

Wähle eine der folgenden:

  • Tech A

  • Tech B

  • both right

  • both wrong

Erklärung

Frage 42 von 56

1

A customer called in complaining that his indoor blower would not stop running. what is the most possible cause of this problem?

Wähle eine der folgenden:

  • a defective blower motor run capacitor

  • contacts stuck open on the fan control

  • contacts stuck closed on the fan control

  • both A and C

Erklärung

Frage 43 von 56

1

after diagnosing a no heat call it has been determined that the induced draft motor is not operating.

Tech A says that it is the fault of an induced draft pressure switch

Tech B states that the indoor blower relay module is defective.

Wähle eine der folgenden:

  • Technician A

  • Technician B

  • both are right

  • both are wrong

Erklärung

Frage 44 von 56

1

The burners on a gas fired furnace are continously lit and setting the thermostat to the off position doesnt not make any difference. What is a possible problem for this fault ?

Wähle eine der folgenden:

  • a defective gas valve

  • a defective fan control

  • a limit control stuck in the closed position

  • a shorted secondary winding on the transformer

Erklärung

Frage 45 von 56

1

a customer complains that she has no head and that the furnace does nothing at all. she says that it is a mid efficiency gas furnace with an induced draft motor and a direct spark ignition system. which of the following would be likely place to start trouble shooting

Wähle eine der folgenden:

  • check the fan door switch

  • check for a blown fuse

  • check for a defective furnace switch

  • all of the above

Erklärung

Frage 46 von 56

1

on a hot surface ignition system the igniter does not glow. what would be the most likely cause of this fault.

Wähle eine der folgenden:

  • a bad flame sensor

  • a bad gas valve

  • a bad closed pressure switch

  • a bad igniter

Erklärung

Frage 47 von 56

1

on a spark ignition system the spark is occurring but its pilot will not light. which one would you check?

Wähle eine der folgenden:

  • terminals PV and MV/Pv for 24 volts

  • test for continuity of PV coil

  • test for the gas to the pilot line

  • all of the above

Erklärung

Frage 48 von 56

1

the thermocouple on a furnace has just been replaced but the pilot light continues to go out. what test should a tech perform?

Wähle eine der folgenden:

  • ensure that the pilot flame is engulfing the tip of the thermocouple 3/8"

  • test continuity of the main valve

  • test for voltage to the main gas valve

  • check for open limit control

Erklärung

Frage 49 von 56

1

an existing thermocouple has been tested with a millitvolt meter and has registered 13 millivolts. which of the following would be the correct action to take?

Wähle eine der folgenden:

  • make sure that the thermostat is calling for heat

  • replace the thermocouple

  • replace the pilot gas valve

  • there is no problem with the thermocouple and it should be left alone.

Erklärung

Frage 50 von 56

1

what is an acceptable voltage for a thermocouple?

Wähle eine der folgenden:

  • 30 milliV

  • 20 milliV

  • 10 milliV

  • 5 milliV

Erklärung

Frage 51 von 56

1

an indoor blower motor will run but it cycles on a internal overload protector using a digital meter.

Tech A states the meter read zero when placing it across the motors run capacitor.

Tech B states that the meter read OL when placing it across the run capacitor.

whos right?

Wähle eine der folgenden:

  • Tech A

  • Tech B

  • Both right

  • both wrong

Erklärung

Frage 52 von 56

1

a furnace has been operating during the mild winters. during the cold days the 3 year old furnace doesnt provide continuous heat to satisfy the demand. the technician does a Btu input measurement by clocking the gas meter and finds the system within specifcations. the temperature rise is also within system limits which of the following would be the most correct diagnosis.

Wähle eine der folgenden:

  • the furnace was undersized in heating capacity

  • the gas pressure needs to be increased

  • the duct work needs redesigning

  • none

Erklärung

Frage 53 von 56

1

during furnace operations the thermostat is quickly satisfied. the new furnace heats the entire house very quickly then shuts off on thermostat demand. which would be the most correct statement of this situation

Wähle eine der folgenden:

  • the thermostat needs replacing

  • the blower speed should be increased

  • the furnace heating capacity is oversized

  • the duct system is too large

Erklärung

Frage 54 von 56

1

Two gas furnaces were installed. Both were 150 MBtu/H (150,000 Btu/H). Both furnaces may operate at the same. when one furnace is running all operations are satisfied. When both furnaces are operating at the same time the burner flames of both furnaces decrease in size. Which procedure is correct.

Wähle eine der folgenden:

  • Replace the heating thermostat

  • Increase the gas pressure regulator of the first furnace

  • replace both gas valves

  • Determine if the gas piping layout is properly sized

Erklärung

Frage 55 von 56

1

On a natural gas to LPG furnace conversation

Tech A states only one burner orifice needs to be changing

Tech B states the orifices gas valve regulator spring and pilot orifice should be changed.

Wähle eine der folgenden:

  • Tech A

  • Tech B

  • both are right

  • both are wrong

Erklärung

Frage 56 von 56

1

A draft test has been performed and it is indicated that there is an improper draft for the gas furnace that is being used. Whcih of the following would be the correct procedure to preform?

Wähle eine der folgenden:

  • Increases the gas pressure

  • increase the inducer draft motor speed

  • check for chimney obstructions

  • replace the heat exchanger

Erklärung

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