G2 Test Questions Flashcards
Underground piping or tubing shall be tested in accordance with the:
Requirements of the B149. 1 Code
What is the allowable maximum distance piping supports should be spaced on a 4 inch horizontal gas line?
15 feet
What is the required minimum distance a purge line may terminate from either a building or air intake when purging a piping tubing system to outdoors?
10 feet
Schedule 80 piping is required in a propane system:
For propane vapour over 125 pisg working pressure
What is the minimum time and pressure required to test a new welded 3 inch NPS piping system that is 220 feet long with a supply pressure of 40 psig?
180 minutes at 60 pisg
Above ground piping of which size and larger must be welded, unlesss the authority having jurisdiction allows threaten joints?
2 and 1/2”
What size tubing is required to supply propane to a 225,000 Btuh input appliance when installing 95 feet of copper tubing which will operate at 2 psig with a pressure drop of 1.0 psig?
0.625” (5/8”)
When is it necessary to purge every branch supply line in a piping system?
Always
When sizing a branch line, what is the minimum size of job fabricated welded fitting that can be used on NPS 6” gas supply header?
3/4” NPS
Natural gas piping in industrial building shall be identified:
With yellow paint or yellow bands
When sizing a brand line, what is the maximum size of job fabricated welded fitting that can be used in a 4” NPS gas supply header?
2” NPS
Armoured cable is called”
BX
When a new appliance is to be installed in a building using steel framing and steel studs and the supply wiring to it will be in contact with the studding. Which of the follow types or wire is acceptable, and the most cost effective?
BX
Voltmeters are connected:
In parallel with the device being checked
A panel mounted ground fault circuit interrupting breaker protects all:
Loads in the circuit served by that breaker
A hard, sharp pilot flame indicates:
The orifice is too small
A good pilot generator should produce what voltage?
750 mV
Which of the following statement is correct?
A ground wire shall not be used as a neutral wire
A zero ohmmeter reading tank between the casing of a solenoid and disconnected wire to the solenoid indicates that:
The coil is shorted to the casing of the device
The instrument used to determine potential difference in an electrical circuit is the:
Voltmeter
As the diameter of a wire increases the resistance:
Decreases
In a normal thermocouple application, the expected drop out reading is from:
2-4 millivolts
The resistance of a wire ___________________ as its temperature rises.
Increases
What is the percentage of the appliance-rated gas is applied to a burner using a two stage gas valve when the thermostat calls for the second stage of heat?
100%
An intermittent pilot is present:
Only until the main burner is lit
Thermostats are selected and rated to switch:
All of the above
Burner interlocking flow switched are generally used on boilers which have _________________ water capacities.
Small
A combustion gas valve contains:
A manual shut off valve an automatic gas valve, a pressure regulator
A hot surface ignitor requires ___________ volts to operate properly.
115 - 125 VAC
Trial for ignition is the time allowed to:
Establish ignition
What happens to the current flow through an infrared scanner when the scanner is exposed to infrared radiation?
Current increases
Which of the following heating systems would be expected to cause problems due to this “distribution effect”?
A forced air furnace with no return openings in the furnace room
The key components of a building as a system are:
The building envelope, external environment, mechanical systems, and the occupants39.
Conduction is:
The transfer of heat particle to particle
Currently, the most common type of building construction is:
Platform
To ensure the main burner cannot operate unless the dampers are in the fully open position, electrically operated automatic combustion air dampers shall be:
Interlocked with the burner control system
A depressurization test conducted on a house will help determine the:
Potential for pressure-induced back drafting in the house
(T/F) If the relative humidity of a room in increased, the air temperature in the room must be increased to maintain the same level of comfort.
False
A proper heat loss calculation has been performed for a house which requires a furnace replacement. The numbers indicate the heat loss is 100,000 Btu/h. Which of following furnace should be selected for the installation?
A 120,000 Btu/h input furnace with an AFUE rating of 85%
To ensure that negative building pressure never causes pressure-induced backdrafting:
Use sealed combustion, direct vent appliances
Air enters the house through a process called _____________.
Infiltration
If too many lava rocks are placed in the rack of a barbeque:
The burner will burn out prematurely
The required clearance to combustible materials above a pendant gas lamp is:
18 inches
What device is used to prove a dryer motor is running?
Centrifugal switch
The pressure relief valve on a propane tank is set at:
250 psig
The closing force in a gas pressure regulator is the:
Pressure downstream of the regulator
A pressure regulator:
Controls outlet pressure
To what specifications are propane cylinders, manufactured in Canada after January 1st 1993, built and marked?
Transport Canada
A worn or dirty seat on a regulator assembly may produce:
High pressure downstream
Propane containers located on the outside of a recreational vehicle shall be:
Mounted on the “A” frame as close to the front of the vehicle as practicable
What is purpose of purging new or reconditioned cylinders?
To remove water and oxygen
If a second stage regulator is adjusted to compensate to undersized piping, one of the results will be:
High lock up pressures
What should be done if it is noticed that a regulator set in a loading dock area is not protected against physical damage?
B) Notify the local gas utility that protection is required
A two stage regulation system on propane will:
B) Reduce fluctuating delivery pressures
Which regulator component is used as a measuring element?
C) The diaphragm
Can a shut-off valve be installed upstream of a relief valve to allow for the removal of the relief valve for servicing without having to empty the contents of the tank?
No
What will happen if the adjusting screw of a regulator is turned counter-clockwise, decreasing the spring tension?
B) The downstream pressure will decrease
Which of the follow best describes a bellows type meter?
One which uses the volume displaced through chambers divided by a flexible material to drive dials
The primary function of a surge arrestor in the top of a regulator is to:
Limit the escape of the gas to 1 cu.ft/hour
What is the largest pronto cylinder manufactured?
420 pounds WC
Which of the following are used in an absorption refrigeration cycle
Ammonia and hydrogen
When a refrigerator develops excessive frost on the evaporator
It becomes less efficient
A propane refrigerator runs on:
Propane, 12 volts D.C and 24 volts D.C
How often should a refrigerator be serviced and cleaned?
At least once a year or as recommended by the manufacturer
Why does the recommended range of CO2 in a converted furnace differ from the ultimate amount of CO2 of 11.9%?
To provide a safety margin
How can the location of a leak in heat exchanger to be determined?
All of the above
What materials are approved for joining single wall vent connectors?
C) Sheet metal screw
. A found draft burner has a blower that produces sufficient pressure to overcome the resistance of the:
B) Burner and the appliance
Two undesirable products of incomplete combustion are:
Carbon monoxide and aldehydes
When it is necessary, where should a vent connector be reduced?
At the breeching of the appliance
The most likely cause of a puddle of water at the side of a water heater where the drain cock and relief valve are located is that:
The relief valve is opening periodically
In combustion heating systems employing a water heater and an air handler, the burner is activated by the temperature sensor in the:
Room thermostat
Temperature Rise”, when applied to a hot water heater is the:
B
Water temperature difference across the heater
The “stacking effect” in a water heater is usually caused by:
Short draws of water from the heater
Combination systems are sized to deliver ______________ of the calculated heat loss of the building.
120%
When determining the position of an air handler and a water heater to be connected for combination heating use, the most important factor to consider from the following is:
Venting of the water heater
As the outlet temperature decreases from a water heater to the heating loop in a combination heating system, the:
Heating output from the air handler decreases
. If a water heater has black scorch marks on the front above the burner access opening, what should be done?
D) Adjust the burner flame and check the flue baffle for soot or scale
Where should the condensate line of condensing furnace terminate?
At an open drain
There is a no heat call for the system, use the following…
Terminals at the thermostat read 24V
Gas valve coil reads 0V
Gas Coil to gas coil common reads 24V
Points across high limit read 0 volts.
Determine which component is open…
Thermostat
There is a no heat call for the system. Use the following…
Thermostat terminals reads 0V
Gas valve coil terminals reads 0V
High limit terminals reads 110V
L & N terminals reads 110V
Determine which component is open:
Thermostat
There is a no heat call for the system, use the following…
Thermostat terminals read 0V
Gas valve coil terminals read 24V
Gas valve (thermostat side) to common terminals read 0V
Gas valve (transformer side) to common terminals read 24V
Determine which component is open:
C) High limit
A furnace is found to be cycling on the high limit. The fan rotation, belt, and the clock input is according to the rating late. What is the most likely problem?
Return air volume too low
The high temperature limit switch in the circuitry if a conventional residential furnace is wired in series with the:
Gas valve
When does an electrically operated automatic vent damper open on mid-efficiency furnace?
Before the ignition cycle
A low water cut off is required on a steam boiler not under continuous attendance by certified operator, when the rated input is:
Any value
Automatic chlorinators must be installed:
Downstream of the heater
The external bypass valve is set by:
D) Determining the temperature rise across the appliance
Scenario: There is a storage type of system. The boiler is hot, the circulating motor is running and the thermostat is called for heat and the upstairs is cold. Most likely the problem is:
D) A broken pump coupling
If it has been determined that a steam boiler is on and the water gauge indicates no water, what should be done immediately?
A) Shut off the fuel supply
A fire tube boiler has:
Water outside the tubes and flue gasses inside
If the bypass valve on a pool heater is closed:
) The flue gasses may condense
Why is a pressure relief valve installed on a pool heater system?
To prevent damage to the system
What type of room heater may be installed in a bathroom?
Direct vent
Dirt pockets are required on:
D) None of the above
Which of the following is acceptable when a fireplace insert is installed?
A) A metal chimney liner
When can a certified hose be used to connect a construction heater to temporary piping?
D) Only when a lever handle shut off valve is installed upstream of the hose
What type of vent must be used when the vent of a wall furnace will be concealed in a partition wall?
D) BW vent
A room heater installed in either a sleeping area or public area shall be:
Equipped with a regulator
What must be done during the installation of a “gas log” fireplace?
Secure the chimney damper in the open position
What must be ensured before electronic cells are removed for cleaning?
C) Cells must be de-energized and discharged
What is the approximate secondary voltage range of an electronic air cleaner?
D) 9000 - 12000 volts
What happens to the system in the heating mode if the pre-filter in an electronic air cleaner gets plugged with dirt?
B) The burner shuts off on high limit
Plate humidifiers operate:
A) All the time the fan is running
What is the purpose of an electronic air cleaner?
D) To remove dust, smoke, and odours from the air
What will happen in a furnace if the cooling coil gets too dirty>
D) The supply air flow will decrease
How are electronic air cleaners wired?
A) In parallel with the fan motor
The primary voltage for duct mounted electronic air cleaners is:
B) 120 - 130 volts
How many duct opening are required for a bypass humidifier?
B) Two
In a domestic air conditioning applications, what is the minimum volume of supply air per ton of cooling required?
C) 400
A combination fan-limit control:
D) Controls the blower operation and shuts the burner off on over temperature
Convection is:
B) Heat transfer through fluids
What would the blow speed be if the motor pulley is twice the diameter of the blower pulley?
D) 2 times the motor speed
If the fan compartment door of an appliance if left off, the motor:
D) Current will increase
In order to prevent condensation from forming on the outside of the a duct, the duct must be
Insulated on the outside
Heat which when added to or removed from a substance causes a change of temperature is called:
D) Sensible heat
Air filtration devices are generally located in the:
C) Return air plenum
An adjustable sheave pulleys the most commonly used on a:
A) Motor shaft
Which of the following must be considered when sizing a branch circuit fuse?
A17: the gauge of the wire
The incoming power supply to residential home is:
A18: 240/1/60
As the length of an electrical run increases, it may be necessary to:
A19: increase the wire size
when using an ohmmeter, the most important thing to remember is to:
A20: De-energize the circuit
Flame rods (flame rectifiers) utilize:
Milliamps
A combination gas valve contains a(n):
A38: manual shut off valve, an automatic gas valve, a pressure regulator
When using a jumper wire to by-pass the thermostat at the gas valve, why should you always disconnect at least on lead of the thermostat
A39: if incorrectly attached, it may burn out the heat anticipator in the thermostat
which of the following is used in high temperature sensing control elements?
A40: mercury
how many volts are required to property operate a hot surface igniter?
A42: 115-125 vac
Which device shuts off the spark igniter in a spark ignition dryer after ignition?
A62: ignition sensor
: if the regulator vent became blocked with the regulator in the open position
A63: there would be excessive downstream gas pressure
A two-stage regulation system in propane will:
A64: reduce fluctuating delivery pressures
excessive gas pressure on the downstream side of a lock-up type pressure regulator can be caused by”
A65: a blocked vent line
temperature compensated meters are installed to:
A66: provide accurate measurement in varying weather conditions
(T/F) the primary function of a surge arrestor in the top of a regulator is to reduce the opening speed of the regulator.
A68: true
Which item is used as a regulator’s resticing element?
A69: the regulator valve
what is the largest propane cylinder manufactured?
A70: 1000lb
78: A relief valve on regulator operates when:
A78: there is excessive pressure in the supply pipping
Pressure regulator on construction heatyerts shall be set to limit the outlet pressure to:
A79: the design operating pressure of the heater
What is the best method of adjusting and setting the pressure on an appliance regulator
A80: adjust the regulator set point using a manometer to the appliance rating
When the .01 cubic meter dial of a natural gas meter indicates movement this means
A81: a leak is present
how often should a refrigerator be serviced and cleaned?
A83: at least once a year or as recommended by the manufacture
Q84:a three way refrigerator runs on:
A84: propane, 12 volts d.c. and 120 volts a.c.
what kind of propane refrigerator can be installed in a recreational vehicle?
A85: an approved direct vent type or equivalent
(T/F) : a generator, evaporator, absorber and condenser are the main components of a gas-fired refrigerator
A86: true
A fan assist burner is designed to
overcome the resistance of the burner only
The person responsible for sizing the burner for a retrofit furnace is the:
A89: Installer
what action should a technician take if a cracked heat exchanger is found in a conventional style furnace?
A112: inform the customer, shut off the gas supply, and inform the fuel supplier
when retrofitting a heating system, a new high efficiency furnas shall be sized according to the:
A113: heat loss of the residence
A furnace is found to be cycling on high limit. The fan rotation, belt, filter and the clocks input is according to the rating plate. What is the most likely problem.
A114:the thermostat heat anticipator is set to high or the return air volume is to low
A customer complains of an unusual noise from the furnace. There is a 24 volt solenoid gas valve working properly, but humming. From the following list, what is the most probable cause?
A115: Low voltage
When an indoor gas-fired pool heater is being replaced, the new finned tuble heater shall be
A122: direct vent type
:A pressure reducing valve:
A125: reduces the city main pressure to a safe working pressure
which device can be used to determine air restriction in a duct system?
A157: manometer
which of the following two measurements are required to determined the relative humidity
A160: dry bulb and wet bulb
convection is:
heat transfer through fluids.
If fresh air is fan controlled and used for combustion air, it must be intertocked with thes ?
gas valve.
If the belt on a blower is too tight. the motor:
current will increase.
What is the blower speed if the motor pulley is twice the diameter of the blower pulley?
2 times the motor speed
