Gas Heat Final

Question 1

A gas furnace is to be installed in a garage. National standards require that the bumers and ignition sources must be located above the floor;
6 inches.
12 inches.
18 inches.
24 inches.

Answer 1

18 Inches

Question 2

To test for an obstructed flue pipe on an induced draft furace, a technician should use;
A. a digital multimeter to test for voltage across the limit switch.
B. a manometer to test the negative pressure generated by the induced draft motor.
C. a manometer to test the outlet pressure of the gas valve.
D. the amp clamp of a multimeter to test the amperage of the induced draft motor.

Answer 2

B. a manometer to test the negative pressure generated by the induced draft motor.

Question 3

Redundant gas valve used on gas furnaces have:
A. dual gas shut off seats.
B. no manual gas shut off.
C. one gas shut off seat.
D. two manual gas shut offs.

Answer 3

A. dual gas shut off seats.

Question 4

Burning one cubic foot of liquified petroleum (LP) gas completely will produce approximately;
A.900-1,100 Btu.
B. 1,200-1,500 Btu.
C. 1,500-2,000 Btu.
D. 2,000-2,500 Btu.

Answer 4

D. 2,000 - 2,500 BTU

Question 5

Liquified petroleum (LP) gas has a specific gravity of;
A 0.4-0.8.
B 1.0-1.1.
C 1.5-2.0.
D 2.5-3.0.

Answer 5

1.5 - 2.0

Question 6

What is the purpose of using an adjustable shutter on older burners?
A Mix combustion and dilution air
B Mix dilution and excess air
C Mix primary air and gas
D Mix primary and secondary air

Answer 6

C. Mix Primary air and gas

Question 7

The primary function of the limit switch is to de-energize the;
A. blower motor if the appliance overheats.
B gas valve if the furnace experiences a flame rollout.
C gas valve if the furnace overheats.
D motor when the heat exchanger reaches the appropriate temperature.

Answer 7

C. Gas valve if the furnace overheats

Question 8

A technician is using an extension ladder to work on a roof top unit. The top of the ladder should extend beyond the support point by;
A 1 foot.
B 2 feet.
C 3 feet.
D 4 feet.

Answer 8

C. 3 Feet

Question 9

.A technician determines that a natural gas furnace has a defective heat exchanger. The technician should;
A inform the gas company and evacuate the home.
B inform the homeowner and turn off the gas supply to the furnace. C turn off the main gas supply to the home.
D. turn the power to the furnace off.

Answer 9

B. Inform the homeowner and turn off the gas supply to the furnace

Question 10

gas pressure usually required at the manifold and burners in a natural gas furnace is;
A 3.5 inches WC.
B 4.2 inches WC.
C 5.0 inches WC.
D 7.0 inches WC.

Answer 10

A. 3.5” WC

Question 11

The National Fuel Gas Code classifies a vent system for a condensing furnace as;
A. Category I.
B. Category II.
C. Category III.
D. Category IV.

Answer 11

D. Category IV

Question 12

The minimum distance Type-B vent pipe must be kept from combustible materials is;
A. one-eighth inch.
B. one-quarter inch.
C. one-half inch.
D. one inch.

Answer 12

D. One Inch

Question 13

Typical CONDENSING furnaces have an efficiency rating of at least;
B.
A. 78%
B. 80%.
C. 82%.
D. 90%.

Answer 13

D. 90%

Question 14

You have installed a Category IV, two-pipe vent system that terminates through the roof of the residence. The elbow for the combustion air intake, above the roof, should;
A. come straight out.
B. have a rain cap.
C. point down.
D. point up.

Answer 14

C. Point Down

Question 15

Higher system efficiency is achieved in a category IV condensing furnace when the water vapor in the flue gas condenses and releases;
A. carbon dioxide.
B. latent heat.
C. primary air.
D. sensible heat.

Answer 15

B. Latent Heat

Question 16

The reason heating thermostats have anticipators or cycle rate adjustment is to;
A. increase lag.
B. increase overshoot.
C. increase temperature swing.
D. reduce temperature swing.

Answer 16

D. Reduce Temperature Swing

Question 17

Natural gas consists primarily of;
A. Butane,
B. methane
C. Octane
D. propane.

Answer 17

B. Methane

Question 18

Burning one cubic foot of natural gas will produce approximately;
A. 900–1,100 Btu.
B. 1,200-1,500 Btu.
C. 1,500-2,000 Btu.
D. 2,000-2,500 Btu.

Answer 18

A. 900 - 1,100 BTU

Question 19

A furnace nameplate specifies a temperature rise of 40 to 70 degrees. Temperature measurements indicate a rise of 80 degrees. The most appropriate action is to;
A. decrease fan speed.
B. increase fan speed.
C. increase the manifold gas pressure.
D. reduce burner size.

Answer 19

B. Increase fan speed

Question 20

A Btu is the amount of heat required to raise the temperature of one pound of water;
A. one-degree Celsius.
B. one-degree Centigrade.
C. one-degree Fahrenheit.
D. one-degree Kelvin.

Answer 20

C. One degree Fahrenheit

Question 21

Pressure drop in a natural gas piping system primarily occurs due to;
A. an improperly sized and incorrectly installed furnace vent system.
B. defects in the appliance gas valve.
C. friction or resistance caused by the pipe and fittings installed in the piping system.
D. the use of piping that is made of a material incompatible with the gas being supplied.

Answer 21

C. Friction or resistance caused by the pipe and fittings installed in the piping system

Question 22

Gas piping must be installed with a pitch of;
A. 1/4 inch per 15-foot run
B. 1/3 inch per 15-foot run
C. 1/2 inch per 15-foot run.
D. 1 inch per 15-foot run.

Answer 22

A. 1/4 inch per 15-foot run

Question 22

Pipe joint compound should be applied to;
A. male threads completely.
B. male threads, less two end threads.
C. female threads.
D. both male and female threads.

Answer 22

A. Male threads completely

Question 23

When a lockout/tagout is used during the service of a system;
A. the general contractor, job site engineer, and technician should all have keys.
B. the key should be stored in a location on the job site that allows anyone access.
C. there should be only one key, kept by the electrician on the job site.
D) there should be only one key, in possession of the technician performing the work.

Answer 23

D. There should only be one key, in possession of the technician performing the work

Question 24

How much combustion air is required to burn and properly vent one cubic foot of natural gas? A. 5 cu ft. B. 10 cu ft. C. 15 cu ft. D. 37.5 cu ft.

Answer 24

B. 10 Cu ft.

Question 25

The ignition temperature of natural gas is; A. 800°F-900°F. B. 900°F-1000°F. C.1000°F-1100°F. D. 1100°F-1200 F.

Answer 25

D. 1100-1200 F

Question 26

The purpose of a flue baffle is to; A. control air to the burner. B. increase heat exchange. C. replace vent fans, D. slow down excess air,

Answer 26

B. Increase heat exchange

Question 26

What volume of flue gas is produced by a 60,000 Btu/h Category I, fan -assisted natural gas furnace operating with 50% excess air? A. 420 cu ft. B. 600 cu ft. C. 780 cu ft. D. 960 cu ft.

Answer 26

D. 960 cu ft

Question 27

Air that is mixed with natural gas in the burner is called; A. combustion air. B. dilution air. C. excess air. D. primary air.

Answer 27

Primary Air

Question 28

The typical marifold pressure for a liquified petroleum (LP) gas appliance should be; A. 2 - 4 inches WC. B. 4 - 6 inches WC. C. 7 - 9 inches WC. D. 10 - 11 inches WC.

Answer 28

D. 10-11 inches WC

Question 29

The efficiency rating of a gas-burning appliance is determined using; A. Annual Fuel Utilization Efficiency (AFUE). B. Energy Efficiency Ratio (EER). C. Home Energy Rating System (HERS). D. Seasonal Energy Efficiency Ratio (SEER).

Answer 29

A. Annual fuel utilization efficiency AFUE

Question 30

Which condition would cause the temperature limit safety switch to shut off the burner? A. Fan motor failure B. Igniter failure C. Low gas pressure D. Vent fan or flue problem

Answer 30

A. Fan motor failure

Question 31

The cut-off plate is a component of the; A. blower housing. B. draft diverter. C. fan motor. D. ignition board.

Answer 31

B. Blower housing

Question 32

A "spud" or burner orifice; A. controls air to the burner. B. controls manifold pressure. C. controls vent fan cycling. D. meters gas to the burner.

Answer 32

D. Meters gas to the burner

Question 33

What reading should a good thermocouple produce on a DC meter? A. 12 volts B. 24 volts C. 30 millivolts D. 250 millivolts

Answer 33

C. 30 millivolts

Question 34

Liquified petroleum (LP) gases are; A. butane and methane. B. butane, methane, and air. C. propane and butane. D. propane, methane, and air.

Answer 34

C. Propane and butane

Question 35

When the burners of a furnace are ignited, the blower motor operation is delayed to; A, allow the heat exchanger to warm up. B prevent the heat exchanger from overheating. C. remove condensation from the manifold D. slow down vent draft.

Answer 35

A. allow the heat exchanger to warm up

Question 36

Which of the following test instruments can be used to check the gas pressure of a furnace? A. Anemometer B. Digital multimeter C. Manometer D. Velometer

Answer 36

C. Manometer

Question 37

The igniter in a hot surface ignition furnace does not energize after the inducer draft motor is energized. The proper action for the technician would be to; A. check for proper low voltage at the igniter. B. check for voltage at the thermostat. C. check for voltage through the pressure switch. D. check gas pressure at the gas valve inlet.

Answer 37

C. Check for voltage through the pressure switch

Question 38

A technician starts a standing pilot furnace and notices when the blower is energized the flames "roll out". The technician correctly suspects; A. cracked heat exchanger. B. high gas pressure. C. incomplete combustion. D. low gas pressure.

Answer 38

A. Cracked heat exchanger

Question 39

A technician servicing an LP gas furnace notices a tag stating it was converted from natural gas. He finds large amounts of soot in the heat exchanger. What could be the probable cause of this soot? A. Incorrect return air velocity. B. Low air flow (CFM). C. Low gas pressure. D. Orifice, (spud) too large.

Answer 39

D. Orifice (spud) too large

Question 40

The proper method for testing flame rectification is; A. placing the meter's amp clamp over the flame sensor wire to test for amperage. B. placing the meter in series with the flame sensor to test the DC microamps. C. placing the meter leads across the gas valve terminals to test for voltage. D. placing the meter leads at both ends of the flame sensor and testing the resistance.

Answer 40

B. Placing the meter in series with the flame sensor to test the DC microamps

Question 41

To react to a change in temperature, the fan/limit switch in a standing pilot furnace uses a helical shaft made of: A. aluminum. B. bi-metal. C. galvanized steel. D. high temperature plastic.

Answer 41

B. Bi metal

Question 42

Type-B vent pipe is constructed with an inner pipe and outer pipe. The inner pipe is made of; A. aluminum. Black iron C. galvanized steel. D. stainless steel.

Answer 42

A. Aluminum

Question 43

What type of draft is used to move flue gas through the heat exchanger and into the venting system in modern gas-fired furnaces? A. Atmospheric B. Mechanical C. Natural D. Neutral

Answer 43

B. Mechanical

Question 44

When venting category I furnaces, it is sometimes necessary to increase the vent pipe size. The proper location to adapt to the larger vent is; A. at the furnace connection. B. one foot above the furnace connection. C. two feet above the furnace connection. D. three feet above the furnace connection.

Answer 44

A. At the furnace connection

Question 45

You are installing 1/2" and 3/4" black iron pipe to a natural gas furnace. When threading, what is the approximate number of threads to cut? A. 4-5 B. 5-6 C. 7 - 10 D. 10 - 12

Answer 45

C. 7-10 Threads

Question 46

The proper name of the tool used to cut the threads of a steel pipe is a: A. die B. pipe cutter. C. ratchet head cutter D. reamer.

Answer 46

A. Die

Question 47

What would likely be the result of an oversized mid-efficiency furnace? A. The flue gas would back up in the draft diverter. B. The furnace would operate at a low temperature split. C. The heat exchanger would corrode. D. The supply gas pressure would drop when the furnace is in operation.

Answer 47

C. The heat exchanger would corrode

Question 48

The normal voltage for a hot surface igniter is; A. 1.5 volts B. 12 volts. C. 48 volts. D. 120 volts.

Answer 48

D. 120 Volts

Question 49

The first section of duct installed on a furnace that connects a furnace to the branch ducts is called the; A. boot. B. cross brace. C. end cap boot. D. Plenum

Answer 49

D. Plenum

Question 50

In residential installations, metal ductwork transmits noise generated by the furnace to the conditioned space. What type of connectors are used to control this? A. Damper eliminating brackets B. Vapor barriers C. Vent dampers D. Vibration eliminators

Answer 50

D. Vibration Eliminators

Question 51

ASHRAE standards specify the maximum allowable CO concentration in a living area is; A. 0 ppm. B. 9 ppm. C. 35 ppm D. 50 ppm.

Answer 51

B. 9 ppm

Question 52

A mid-efficiency, category I natural gas furnace has a typical air temperature rise of; A. 40°F-50°F B. 40°F-70°F. C. 60°F-100°F. D. 60°F- 120°F.

Answer 52

B. 40-70F

Question 53

A furnace that is designed with the blower motor located beneath the heat exchanger is called a(n); A. bi-flow. B. downflow. C. horizontal. D. upflow.

Answer 53

D. Upflow

Question 54

The severity of an electric shock is determined by the; A. intensity of electric current flow and its path through the body. B. the amount of voltage and its path through the body. C. the amount of voltage and the length of time the body is exposed to it. D. the intensity of the electric current and the amount of voltage.

Answer 54

A. intensity of electric current flow and its path through the body

Question 55

A homeowner complained that his furnace makes a loud bang upon ignition. The technician decides to check the gas pressure and finds 2.2” WC at the manifold. The technician should; A. check supply gas pressure. B. check the vent system. C. decrease manifold gas pressure. D. increase vent pipe size.

Answer 55

A. Check supply gas pressure

Question 56

How much current is typically conducted through the flame sensor? A. 1-10 microamps B. 30-200 microamps C. 1-3 picoamps D. 300-200 picoamps

Answer 56

A. 1-10 microamps

Question 57

A typical vent stack temperature on a natural draft furnace is; A. 100°F-120°F. B. 280°F-300°F. C. 350°F-450°F D. 450°F-550°F.

Answer 57

C. 350-450F

Question 58

A customer complains that a 2-year-old, direct, hot surface ignition furnace will not light. The inducer motor runs, the pressure switch closes, and the igniter begins to glow, but there is no ignition. The furnace locks out while attempting to light. After resetting the furnace, 17 VAC is measured at the gas valve and the technician correctly concludes; A. the electronic board is faulty. B. the gas valve is shorted. C. the transformer is faulty. D. weak heat anticipator.

Answer 58

A. The electronic board is faulty

Question 59

The pilot assembly orifice of a spark ignition furnace is completely clogged. The technician should; A. replace it. B. soak it in a coil cleaning solution. C. soak it in penetrating oil. D. use an awl to clean it.

Answer 59

A. Replace it

Question 60

Carbon monoxide (CO) is dangerous. What is the maximum level of undiluted CO that is acceptable in a sample of the flue gas? A. 400 pm B. 800 ppm C. 1000 ppm D. 1800 ppm

Answer 60

A. 400 ppm

Question 61

A technician starts up a natural gas furnace. The main burner lights and after 60 seconds the blower fan comes on, but the burner flames waver in one corner. The technician suspects; A. a faulty blower housing. B. a faulty heat exchanger. C. a faulty vent system. D. faulty burners.

Answer 61

B. a faulty heat exchanger

Question 62

A technician starts an intermittent spark ignition furnace. The pilot flame lights, but the spark igniter continues to spark. After 90 seconds, the pilot goes out and the ignition sequence starts again. The technician suspects a faulty; A. fan switch. B. ignition board. C. limit switch. D. thermostat.

Answer 62

B. Ignition Board

Question 63

The proper instrument for determining the percentage of carbon dioxide in the flue gas of a gas-burning furnace is a; A. Anemometer. B. combustion analyzer. C. draft gauge. D. manometer.

Answer 63

B. Combustion Analyzer

Question 64

If voltage is applied across two speed terminals on a fan motor at the same time, the motor will; A. change rotation. B. run too fast. C. run too slow. D. short out/burn out.

Answer 64

D. Short out / Burn out

Question 65

The recommended external static pressure on a typical gas furnace blower system is; A. 0.1-0.2 inches WC. B. 0.2-0.6 inches WC. C. 0.7-0.9 inches WC. D. 1.0-1.5 inches WC.

Answer 65

B. 0.2 - 0.6" WC

Question 66

When exposed to low concentrations of carbon monoxide, healthy adults may exhibit; A. dizziness and drowsiness. B. headaches and nausea. C. nasal congestion and head pressure. D. no negative symptoms

Answer 66

B. Headaches and Nausea

Question 67

A furnace that is designed with the blower motor located above the heat exchangers is called a(n); A. bi-flow B. Downflow C. Horizontal D. upflow

Answer 67

B. Downflow

Question 68

Which of the following statements is true regarding personal protective equipment (PPE)? A. PPE can eliminate hazards on a job site creating a safe work environment for everyone at the Job site B. PPE can minimize a worker's exposure to job site hazards, but it does not eliminate those hazards. C. PPE must be purchased from a certified equipment wholesaler to guarantee authenticity. D. PPE requirements are determined by the job site engineer and the worker performing the task.

Answer 68

B. PPE can minimize a workers exposure to job site hazards, but it does not eliminate those hazards

Question 69

Most thermostats contain one or more sets of contacts to control the heating system of a conditioned space. These contacts; A. are controlled manually. B. are thermally actuated. C. can be replaced if they fail. D. have a moisture sensing element.

Answer 69

B. Are thermally actuated

Question 70

To change the cubic feet per minute (CFM) being delivered by a single-speed belt-driven blower, the technician should adjust; A. both the motor and blower wheel pulleys. B. the blower cutoff plate. C. the blower wheel diameter. D. the motor pulley size.

Answer 70

B. The blower cutoff plate

Question 71

The formula (x = Btu/hr Output) is used to calculate; A. CFM B. FPM C. latent heat D. sensible heat

Answer 71

A. CFM

Question 72

The most common burner used in induced draft furnaces is; A. inshot. B. Potted. C. ribbon. D. single port.

Answer 72

A. Inshot

Question 73

A furnace that is direct ignition; A. energizes the blower motor before lighting the main burners. B. has a manually lit pilot flame that lights the main burners. C. lights a pilot flame with and electronic igniter. D. lights the main burners with an electronic igniter.

Answer 73

D. lights the burners with an electronic igniter

Question 74

A standing pilot gas valve with 100% shut-off means; A. gas to the pilot and manifold is shut-off. B. gas to the burner and regulator is shut-off. C. gas to the manifold and burner is shut-off. D. gas to the regulator and burner is shut-off.

Answer 74

A. Gas to the pilot and manifold is shut off.

Question 75

A gas furnace has an integrated furnace control (IFC). How is the fan cycled during heating? A. Cooling bi-metal B. Heat relay C. Temperature D. Time

Answer 75

D. Time

Question 76

A primary cause of burner "flashback" is; A. excessive combustion air. B. excessive primary air. C. high manifold pressure. D. low manifold pressure.

Answer 76

D. Low manifold pressure

Question 77

The reason for a cross-lighter or carryover on a gas burner is to; A. prevent short cycling. B. prevent soot buildup. C. provide secondary air. D. provide smooth lighting of all burners.

Answer 77

D. Provide smooth lighting of all burners

Question 78

The lowest concentration of fuel at which an air/fuel mixture will ignite, if exposed to an ignition source is called; A. LEL. B. PPM. C. TWA. D. VEL.

Answer 78

A. LEL (Lower explosive Limit)

Question 79

A gas furnace is equipped with an induced draft motor. Once the motor is energized, which switch must operate properly for the ignition sequence to continue to the igniter? A. Dilution air B. Fan limit C. Pressure switch D. Rollout

Answer 79

C. Pressure Switch

Question 80

A technician reads zero (0) Ohms between the common and low speed wires on a 120 VAC PSC furnace motor. From this, the technician determines that the winding is; A. grounded. B. ok C. open D shorted.

Answer 80

D. Shorted

Question 81

When using an ohmmeter, a technician reads infinity between the high speed and common wires on a 120 VAC furnace motor. What does this indicate? A. Grounded B. OK C. Open D. Shorted

Answer 81

C. Open

Question 82

When using a digital multimeter to test the resistance of a hot surface igniter, a technician should; A. allow the igniter to cool to room temperature prior to testing. B. place the meter in series with igniter and energize it. C. test each wire of the igniter to ground. D. test the igniter at its ignition temperature.

Answer 82

A. Allow the igniter to cool to room temperature prior to testing

Question 83

Constant-airflow, constant-torque, and constant-speed are all types of; A. CSCR motors. B. CSIR motors. C. PSC motors. D. ECM motors.

Answer 83

D. ECM Motors

Question 84

When installing the vent pipe for a category IV condensing furnace, the proper pitch for the flue the pipe is; A. 1/4-inch per foot. B. 1/4-inch per 10 feet. C. 1/2-inch per foot. D. 1/2-inch per 10 feet.

Answer 84

A. 1/4-inch per foot

Question 85

A spark igniter typically operates at; A. 1,000 VAC. B. 5,000 VAC. C. 6,000 VAC. D. 7,500 VAC and higher.

Answer 85

D. 7,500 VAC and higher

Question 86

An electronic control that is responsible for all the functions of a furnace is called a(n); A. integrated control. B. intermittent ignition control. C. fan delay timer. D. non-integrated control.

Answer 86

A. Integrated Control

Question 87

The diameter of a gas bumer is reduced before gradually becoming larger. This design acts to lower the pressure but increase the velocity of the gas as it flows down the burner tube. It is referred to as the; A. Choke B. Orifice C. spud. D. venturi.

Answer 87

D. Venturi

Question 88

A dedicated vent system; A. is a manifold vent for an appliance. B. is a multi-position vent for an appliance. C. is the only vent for an appliance. D. serves a combination of appliances.

Answer 88

C. Is the only vent for an appliance

Question 89

Which of the following must be present for combustion to occur? A. Air, fuel and ignition source (heat). B. Fuel, hydrogen, and ignition source (heat). C. Nitrogen, fuel, and ignition source (heat). D. Nitrogen and oxygen in the ambient air.

Answer 89

A. Air, fuel, and ignition source (heat)

Question 90

Which of the following statements is true of nitrogen? A. Nitrogen aides in decreasing combustion by-products. B. Nitrogen can combine with oxygen to form NOx. C. Nitrogen increases combustion efficiency by absorbing heat D. Nitrogen promotes complete combustion.

Answer 90

B. Nitrogen can combine with oxygen to form NOx

Question 91

Flashback indicates; A. a pilot that is oversized. B. incomplete combustion is occurring. C. the gas is flowing slower than the speed at which burn is occurring. D. the gas velocity is faster than the speed at which the gas can burn.

Answer 91

C. The gas is flowing slower than the speed at which burn is occuring

Question 92

The highest concentration of fuel at which the air/fuel mixture will ignite if exposed to an ignition source is called; A. LEL. B. PPM. C. TWA. D. UEL.

Answer 92

D. UEL (upper explosive limit)

Question 93

To check for proper airflow range for a furnace, a technician should use; A. the CFM called for on the data plate. B. the RPMs of the blower motor. C. the temperature rise called for on the data plate. D. volumetric pressure

Answer 93

C. The temperature rise called for on the data plate

Question 94

Which of the following statement(s) related to confined spaces is/are correct, as defined by OSHA? 1)Confined spaces have limited access for entry and exit. 2)Confined spaces are large enough for a person to enter and perform a specific job. 3)Confined spaces are not intended to be continuously occupied by humans. A. All three of these conditions must apply to be classified as a confined space. B. Any two of these conditions must apply to be classified as a confined space. C. Number one is the most important and must be applied to classify a confined space. D. Any one of these conditions can classify a work area as a confined space.

Answer 94

A. All three of these conditions must apply to be classified as a confined space

Question 95

A fumace that is designed to be installed in different configurations is called a(n); A. bi-flow. B. Counterflow. C. horizontal. D. multi-position.

Answer 95

D. Multi-Position

Question 96

Uncontrolled air which leaks into the combustion area of a heating appliance through any opening not designed by the manufacturer is called; A. dilution air. B. primary air. C. secondary air. D. tramp air.

Answer 96

D. Tramp air

Question 97

While evaluating a gas valve that failed to open, the technician determined that: 1) the gas valve knob was in the proper position; 2) the thermostat was calling for heat; 3) the valve is an electric ignition type; 4) resistance of the main gas valve coil was good; 5) proper voltage was present at the main gas valve coil terminal(s). What action should be taken next? A. Check the primary side of the transformer. B. Check the secondary side of the transformer. C. Replace the gas valve. D. The problem is in the limit switch.

Answer 97

C. Replace the gas valve

Question 98

On an induced draft, hot surface ignition furnace, the inducer motor runs, but the igniter does not come on. A check of the pressure switch reveals that the switch is open. A digital manometer measures a pressure of -1.12 inches WC at the inducer motor. The rating printed on the pressure switch is - 55 inches WC. The technician diagnoses an); A. clogged flue pipe. B. cracked heat exchanger. C. inducer motor failure. D. pressure switch failure.

Answer 98

D. Pressure Switch failure