Appliances 2 Flashcards
When connecting to a water heater, what minimum length of metallic piping should be installed before connecting to plastic water distribution piping?
18 in (450 mm)
Before starting any repairs, you should turn off the gas supply and allow the glass to cool.
T or F
true
During the lighting of a barbecue, the lid must be closed.
T or F
False
Which of the following conditions are not regulated in a hot water boiler?
Venting pressure
What type of water heater is most commonly used for residential and low-demand commercial installations?
Direct-fired storage heaters
How does the steam supply hose or pipe have to be installed on a self-contained steam humidifier?
Pitched down from dispersion tube to humidifier
What is the draft pressure in the vent from a condensing furnace?
Positive
The heating output of an air handler should exceed the calculated space heating loss of the building it serves.
T or F
true
Because electrostatic filters are a form of slab filter, they are installed in the same position and way as slab filters.
T or F
T
How are gas ranges typically connected to the electrical power supply?
A power supply cord with a 120 VAC three-prong grounded plug
When a tank may be subject to back siphonage, what must be installed?
Vacuum relief valve
What happens when a fluid is heated?
It expands and becomes lighter
How is temperature rise determined?
Subtract the return air temperature from the supply air temperature
What type of gas fireplace is used to convert an existing wood burning masonry chimney to gas?
Insert
Generally, the bypass screw is factory-adjusted and should not be modified.
T or F
True
How does a sealed gas burner design maintain clean burner ports?
Burner cap deflects debris away from the flame
Barbecues equipped with a piezo ignition can be match-lit?
T or F
True
A thermocouple must de-energize the pilotstat coil within how many seconds?
90
Refrigerant circulates between the “A” coil and the condenser coil. What occurs in the A coil?
Liquid refrigerant absorbs heat and changes to the vapour state
What device controls the operation of a humidifier?
Humidistat
What damage can a dirty filter do in a system that includes add-on air conditioning?
Any of the choices could occur
Calculate the velocity of water in ¾ inch ID tubing if the flow rate required for the heating circuit is 5.5 USGPM.
4 ft/sec
A closed limit switch should have resistance.
No
Must a defective heat exchanger in a dwelling unit be replaced immediately?
No, it can be temporarily repaired
Do all rollout switches have to be manually reset?
T or F
False
Why is it important to keep the condenser and absorber fins clean?
To ensure good heat transfer
Combination systems are designed to provide a combination of domestic water heating and space heating.
T or F
True
After you have cleaned all of the burner components, there is still a yellow, lazy flame what should be checked next?
Gas pressure
How is a burner orifice cleaned?
Soak it in non-oily solvents and then blow air through it.
What is the purpose of a meter “dial test”?
To test for leaks in the system up to the inlets of the gas controls
If there are no manufacturer’s rating plate clearances, what are the allowable code clearances to combustibles from the top, back and sides of a domestic gas dryer?
150 mm
An “open system” has no contact with the atmosphere at any point.
T or F
F
Through which device is fuel discharged to an atmospheric burner?
orifice
When would a gas technician/fitter use an incline manometer?
To complete an external static pressure test
What contributes to the formation of lime scale in a water heater?
Hardness
If the temperature of a NTC (Negative Temperature thermistor) decreases, its resistance will .
Increase
How long could it take to suffer a third-degree burn if a person was exposed to water at 140°F (60 °C)?
4 seconds
A dirty cooling coil can restrict the air flow. What would be the effect on the temperature change of the forced air furnace during the heating season?
The temperature rise would increase
To ensure customers have the best air quality it is recommended to always install a filter with the highest MERV rating
T or F
False
What three types of gas-fired units are used to heat a single room or other small areas?
Room space heaters, Wall furnace, Baseboard heater
Under what conditions may an appliance not certified for conversion be converted?
The conversion must be tested and labelled by the inspection authority or an agency authorized by the inspection authority
Which atmospheric burners are most susceptible to flashback?
mono-port
What is the recommended water heater capacity for an air handler rated for 1200 cfm?
60 USG
What device allows dilution air to enter the venting system of an atmospherically fired appliance?
Draft hood
What type(s) of furnace(s) use an inducer fan?
Mid-efficiency and high-efficiency
What component is designed to cause the burner to shut down if there is a blockage in the vent?
Pressure switch
What are the installer’s responsibilities regarding the propane supply system when conducting a conversion from propane to natural gas and the propane tank is no longer going to be used?
Shut off all valves, disconnect the pipe or tubing, plug the openings
When adjusting the minimum heat input, what can happen if the setting is not low enough?
Over-cooling
What type of direct vent uses to completely separate pipes?
Collinear
What must be obtained before electrical work can be performed on gas-fired equipment?
A permit
How many volts are in 250 mV?
0.25 V
How many volts are in 250 mV?
A) voltmeter
B) ammeter
C) ohmmeter
D) All of the above
All of the above
Total electrical resistance in a control system includes the heat anticipator in the thermostat.
T of F
True
Correctly complete the following statement with the appropriate word provided.
R-C circuits are those that have both resistance and __________________.
Reactance
What type of circuit allows current to flow through more than one complete path?
Parallel circuit
Where do branch circuits start?
At the distribution panel
List Thermostats are an example of a control that can be recalibrated or readjusted.
T or F
true
Which type of electrical current flows in both directions?
Alternating
This type of start relay uses transistors, diodes and triacs to break the start windings circuit at the correct time.
Solid-state relay
A PTC (positive temperature coefficient) thermistor will decrease its resistance with a temperature increase.
T or F
False
What is the unit to measure electrical power?
watts or horsepower
How are components represented on connection diagrams?
by symbols
What must be the electrical source for heating equipment rated 400 000 Btu/h and less?
a single branch circuit used for no other purpose
What is the primary cause of motor insulation failure?
Motor overheating
Select the combustion safety controls that work on the principle of flame ionization.
Flame rectifier (flame rod)
Control valves open and close in response to changes in temperature, pressure, humidity, or fluid flow.
T or F
true
Should an ohmmeter be connected into a live circuit?
no
Correctly complete the following statement with the appropriate word provided: ___________ is when all energy sources including electrical, pneumatic, hydraulic, or gravitational are made inoperative.
Zero mechanical state
What is a DIP switch?
A manual electric switch that is packaged with others in a group
What is the operation of a flame rollout switch?
NC switch that opens on flame roll out
A continuity check is a measurement of what?
Resistance
Who may remove a lock used to lock-out equipment?
The person who installed the lock. In an emergency, a supervisor
This start relay has a normally closed set of start winding contacts that are opened by the relay coil after the motor has started.
Potential relay
On what type of gas appliance would a rod and Tube (Unitrol) valve typically be installed?
Gas water heater
The sequence of operation of a circuit can be determined from what kind of drawing?
Schematic diagram
Integrated electronic control boards have replaced most time delay relays.
T or F
True
Which of the follow is not a ferromagnetic metal?
Copper
Which of the following should you not do when rescuing a victim of electrical shock?
Touch the energized victim
What are the two main parts of an electric motor?
Stator and rotor
Crimp-on connectors are convenient to use as they do not require any special tools.
T or F
False
Switches must be in what position to conduct electrical current?
Closed
What two ways can the stator phase coils in a three-phase induction motor be connected?
Delta or wye
From which vantage point is the motor’s direction of rotation viewed?
From the drive end of motor
A thermocouple should be replaced if it cannot produce a closed circuit reading of more than.
8 mV
Complete the following statement with the appropriate word(s) provided:
A conductor having white insulation is normally connected to the ______________ colored terminal on a 120 V ac receptacle.
White or silvery
What is the purpose of an electrical switch?
To open or close an electrical circuit as required
The manufacturer recommends maximum lengths of wiring runs for self-powered control systems.
One alternating sinusoidal wave form
“Self-regulating” means that as the current flow to the secondary winding changes, the primary current flow also changes.
T or F
true
You can determine the sequence of operation for all components connected to an IFC from the wiring diagrams.
False
Select the best description for the term “linear scale”.
A linear scale has ten large equal divisions each located next to a number.
A schematic diagram shows the electrical relationship between components in a circuit, while a wiring diagram shows how components are actually wired.
T or F
True
How many ohms are in 2.125 kΩ
2125
SCR, TRIAC, and DIAC are all what types of electronic devices?
Thyristor
What type of diagram is most helpful when trying to trace wires?
Connection diagram
