Gas - Worksheets Flashcards
An atom has one of its electrons removed and becomes a charged particle known as an “ion”. What is the charge on this ion?
Positive.
What determines whether a material is going to be a good conductor or a good insulator?
Number of valence electrons.
Magnetism caused by the movement of electrons is the definition of?
State 2 places where gasfitters would use the defintion of the description above.
Electromagnetism.
Gas valves and safety valves.
Of the six sources of electricity which are the two most used in the gas fitting industry? Of those two are they sources of direct current or alternating current?
Heat - Direct current.
Magnetism - Alternating current.
Define direct current and alternating current.
Direct current - One direction only.
Alternating current - Both directions.
An abnormal connection between two nodes of an electric circuit intended to be at different voltages is the defintion of?
Short circuit.
What is the order of components in an electrical circuit?
A. Source Switch Load.
B. Switch Load Source.
C. Load Source Switch.
D. Conductor Load Source.
A. Source Switch Load.
Where are the three particles present in an atom located in the atom?
Electron: Revolves around the nucleus.
Neutron: Located in the center of the nucleus.
Proton[][]: Located in the center of the nucleus.
What is an ion?
A negatively or positively charged atom.
What is the “law of electrical charges”?
“Like charges repel and unlike charges attract.”
What is the force that keeps electrons in their orbit and what is the force that is trying to move the electrons out of their orbit?
“Attraction of the nucleus” keeps the electrons in their orbit.
“Centrifugal force” tries to move the electrons out of their orbit.
Why is it important to understand valence shells when dealing with electricity?
The electrons in the valence shell are the electrons that are set free most easily.
The flow of tiny particles (electrons) is the definition of?
Electrical current.
A force created by magnets is the definition of?
Magnetism.
Magnetism caused by the movement of electrons is the defintion of?
Electromagnetism.
What are some uses of electromagnetism?
CD Players.
Clocks[][][][]]
Cranes[][][][]]
Generators.
Motors[][][][]]
Testers[][][][]]
Washing Machines.
A scenario where there is a complete path for electricity to flow is the definition of?
Electric circuit.
What components are essential in an electric circuit?
Source - Switch - Load.
Basic measure of a quantity of electrical charge is the definition of?
Coloumb.
What is voltage?
How do you measure voltage?
Electrical pressure.
Multimeter/Voltmeter.
What is current?
How do you measure current?
Electrical Flow.
Measured in amps or amperes.
What is ohm’s?
How do you measure ohm’s?
Electrical resistance.
Measured in ohm’s[][]
What is ohm’s law for power?
P = E x I.
All loads wired to each other.
One goes out, all go out[][][][][]
Operating controls should be wired this way.
Voltage decreases as loads are added to the circuit.
Current remains constant[][][][][][][][][][][][][][][][][][][][][][][][][][][]
Series circuit.
All loads are wired independantely of each other.
One goes out, other loads remain energized[][][][]]
Fan or pump should be wired in this manner[][][][][]
Ampacity decreases as loads are added to the circuit.
Voltage remains constant[][][][][][][][][][][][][][][][][][][][][][][][][][][]
Parallel circuit.
What is polarity when dealing with electric circuits?
Positive/Negative.
What is the waveform generated by an AC current?
Sine wave.
What is the waveform generated by a DC current?
Straight line.
What does the term phasing refer to when dealing with electricity?
Getting the electricity to go in a certain direction to start.
What’s the frequency of an AC generator here in North America?
60 hertz.
Which kills you, current or voltage?
Current.
How many millvolts does a thermocouple produce when new?
How about a thermopile?[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
When would you use a thermopile instead of a thermocouple[]?
Thermocouple - 30mV.
Thermopile - 250mV-750mV.
Thermopile produces enough voltage to power a control circuit and safety circuit.
What is the difference between an operating aquastat and a high limit aquastat?
If you were wiring these in a system how would they be wired in relation to each other?
Operating Aquastat (160°F - 180°F).
High Limit Aquastat (200°F)[][][][][][]]
They would be wired in series[][][][]]
Operating steampressure switches on steamboilers.
High limit just adjusted to a higher pressure setting[]
Is the definition of?[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
Pressuretrol / High limit pressuretrol.
Keeps the room temperature close to set point is the definition of?
What amperage is this device set to? How do you set that amperage?
Heat anticipator.
Set to the amperage of the gas valve. Set with a knob on the front of the thermostat.
What type of fan switch is on a furnace?
Explain how it works. What are the “FAN ON” and “FAN OFF” setpoints?
Why is there a difference[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]?
Reverse Acting Tempurature Actuated Switch.
Closes on a rise in heat. Fan On - 115°F / Fan Off - 90/95°F.
There is a difference so the fan doesn’t constantly cycle on and off.
You’ve been asked to service a furnace. The first thing you notice is that the burner is on and running smoothly. You also notice that the fan seems to come on and then go off quite frequently. What could be the issue?
Fan set at too high of a speed[][][][][][][][][]]
Fan switch set points could be too close.
How would you go about testing the high limit setting on a furnace?
Disable the fan (Heat goes up - Find out if high limit setting is working).
You are servicing a boiler system. The system calls for heat and the boiler startup routine begins. It goes through the motions but the burner does not fire. This occures 3 times and then the appliance goes into lockup mode. What is your first course of action?
Check Gas (Source).
Check Power (Source).
What is the funtion of the pressure (vacuum) swith on a mid effictient fan assist appliance?
Proving switch for fan.
Explain what a zone valve is for and how it operates.
What are the four wires on the zone valve needed for? What are their colours and where are they wired in to?
Opens/Closes hydronic heating system.
2Red[][][][][][][][][] - End switch(s) Orange/Yellow - Zone valve motor.
What is the function of the end switch on a zone valve?
How does the end switch end up in the closed position?
Proving switch.
Motor/Valve all the way open.
Are the fan circuit and the control circuit wired in series or in parallel on a furnace? Why?
Parallel.
Want fan circuit to work with control circuit but not at the same time.
What type of transformer do we most often use in the heating trade?
120VAC - 24VAC.
What is a relay used for and how does it work?
What voltage does this device use[][][][][][][][][][]]?
Are the contacts in this device normally open or closed?
Used for one circuit controlling another circuit (Diff Volts).
120VAC - 24VAC[][][][][][][][][][][][][][]][][][][][][][][][][][][][][][][][][][][][][][]
Normally open and normally closed. When relays are fired up they reverse position.
Detecting the prescence or abscence of a pilot flame is the job of the?
Combustion safety circuit.
What type of pilot does the combustion safty circuit use?
Constant/Standing pilot.
What does the thermocouple attach to in the gas valve in order to work the safety shut off valve?
Safety shut off valve.
What does the control circuit control?
Main gas valve.
Name the four manual switches.
Single Pole, Single Throw Switch.
Single Pole, Double Throw Switch.
Double Pole, Single Throw Switch.
Double Pole, Double Throw Switch.
If a switch is not operated manually what are three other forces that switches can respond to?
Fluid movement.
Pressure[][][][][][][]]
Temperature[][][][]]
What does a thermostat respond to?
Air temperature changes.
What is a heat anticipator adjusted to in relation to a thermostat?
Adjusted to the amperage rating of the gas valve.
Actuates in response to an excessive rise in air tempurature is the definition of?
Is this device normally closed or open and why[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]?
High limit switch.
It is normally closed but opens the control circuit if overheating occurs.
Actuates in response to fluid movement. If the water level in the boiler falls below the minimum level, the __________________ opens its contacts and cuts off power to the main gas valve. Is the definition/function of?
Low water cut off.
What is the function of a flow switch?
Which component in the boiler system is the flow switching acting as a proving switch for?
Where would be the best location to install a flow switch[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]?
Actuates in response to water movement.
The Pumps[][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
Downstream on the pump on the horizontal run of pipe.
What is another name for a flow switch which senses air flow?
Sail switch.
Actuates in response to changes in water, steam, air or gas pressure is the defintion of?
Pressure switch.
Volts on primary / Volts on secondary Equals Turns on primary / Turns on secondary is the definition of how a _________ works.
Transformer.
How do we size transformers?
Is this rating on the primary or secondary side?
VA = Voltage x Amperage
According to the amount of power the secondary winding can handle.
Bypass for switch to operate the fan is the definition of?
Summer switch.
Are the fan switch and summer switch wired in series or parallel?
Parallel.
How much larger should the grounding area be on a flame rectification system than the flame electrode?
4 times.
The time allowed to establish a pilot flame after the pilot valve and ignition source are energized is the definition of?
Trial for ignition.
Under 400,000 Btu/h does not exceed 10 seconds.
Over 400,000 But/h does not exceed 5 seconds[][]]
What happens to the control module if the trial for ignition period of time expires is the definition of?
Lockout.
The time it takes the flame sensor circuits to react to a flame failure and de-energize the main gas valve is the definition of?
Flame failure response time.
Under 400,000 Btu/h Natural Gas: 90 Seconds LP Gas: 20 Seconds
Over 400,000 Btu/h: 4 Seconds[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
Present only during the operation of the main burner is the definition of?
Intermittent pilot.
Directly lights the main burner with a spark is the definition of?
DSI (Direct spark igniter).
Hot surface lights the main burner is the definition of?
HSI (Hot surface igniter).
In an electrical circuit the black wire is considered to be:
A. The hot wire.
B. The neutral wire.
C. The grounding wire.
D. The negative terminal wire.
A. The hot wire.
When an electrical circuit is switched open:
A. Power travels to the load.
B. Power to the load is interrupted.
C. Power to the load is reversed[][][][]]
D. Power to the load alternates directions.
B. Power to the load is interrupted.
A staple shorting across the thermostat wiring could cause:
A. The appliance to run continuously.
B. The transformer to burn out[][][][][][]]
C. The blower motor to stop working.
D. The burner to overfire[][][][][][][][][][][]]
A. The appliance to run continuously.
Directly proportional to the voltage and inversly proportional to the resistance is the definition of?
Ohm’s law.
True or False?
A short circuit means that the hot wire is touching something that conducts electricity in a direct path to ground with little or no resistence.
True.
Normal residential wiring circuits for receptacles and light fixtures use __ AWG wiring:
A. 10.
B. 12.
C. 14.
D. 18.
C. 14.
Non-metallic sheathed cable marked “12/3” contains:
A. Three #12 wires.
B. Twelve #3 wires.
C. One #12 wire and one #3 wire.
A. Three #12 wires.
Flexible armoured cable is usually referred to as:
A. Romex cable.
B. Conduit cable.
C. BX cable[][][][][][]
D. Sheathed cable.
C. BX cable.
When wiring a switch, the black wire should be connected to the ____-coloured terminal:
A. Green.
B. Silver[]
C. Brass[]
D. Black[]
C. Brass.
True or False?
A continuity test should not be performed until you are assured that there is power going through the circuit.
False.
Multi-meters are usually equipped with:
A red lead wire for the positive terminal and a black lead wire for the negative terminal.
True or False?
The VA rating of a transformer is the total voltage divided by the amperage that is allowed for the transformer.
False.
True or False?
If the heat anticipator of the thermostat is set too high, the tempurature in the room may become warmer than desired.
True.
The most common type of electrical switch found in a residential building is:
A. A SPST switch.
B. A SPSD switch.
C. A DPST switch[]
D. A DPDT switch[]
A. A SPST switch.
Most residential forced warm air furnaces are equipped with a __ VAC thermostat:
A. 240.
B. 120.
C. 24[]
D. 10[]]
C. 24.
A hot water boiler uses a relay to:
Start and stop a 120VAC circulating pump with a 24VAC switch.
A spill switch is usually located:
A. At the outlet of the gas valve.
B. Next to the control module[][]]
C. At the discharge of the draft diverter.
D. At the point where the atmospheric burner enters the combustion chamber.
C. At the discharge of the draft diverter.
True or False?
Electrially-operated vent dampers are connected in parallel to the gas valve.
False.
On a laddergram, it is common practice to draw the hot line on the __ -hand side of the drawing.
A. Left.
B. Right.
A. Left.
After the thermostat contacts have opened, the vent damper should move to:
A. The fully closed position.
B. The fully open position[][]]
C. The neutral position[][][][][]
A. The fully closed position.
In a millivolt system, the distance from the gas valve to the thermostat should be limited to a length of:
A. 100 feet.
B. 75 feet[]
C. 50 feet[]
D. 30 feet[]
D. 30 feet.
If the thermostat on a millivolt system is equipped with a heat anticipator, the meter reading at the thermostat contacts of the gas valve should indicate a reading of:
A. Not more than 50 mV.
B. Not less than 50 mV[]
C. Not more than 110 mV.
D. Not less than 110 mV[]]
C. Not more than 110 mV.
If a step-down transformer is in phase, the meter reading across the two hot wires should be approximately:
A. 144 VAC.
B. 120 VAC.
C. 96 VAC[]
D. 24 VAC[]
E. O VAC[][]
C. 96 VAC.
A standard thermocouple should produce a closed circuit test of approximately:
A. 25 to 30 mV.
B. 10 to 15 mV[]
C. 9 to 10 mV[]]
D. 2 to 5 mV[][]]
B. 10 to 15 mV.
Incorrectly adjusting the heat anticipator of a room thermostat could result in:
A. The circulating fan running continuously.
B. The appliances staying on for longer or shorter time than required.
C. The burners not coming on when required[][][][][][][][][][][][][][][][][][][][][][]]
D. The circulating fan not operating at all[][][][][][][][][][][][][][][][][][][][][][][][][][]]
B. The appliances staying on for longer or shorter time than required.
The numbers on the scale of the thermostat heat anticipator relate to:
The current draw of the control circuit on the appliance.
On a 24 VAC control system, the safety shutoff valve recieves its power from:
A. The transformer.
B. The thermopile[][]
C. The thermocouple.
D. The flame safeguard.
C. The thermocouple.
True or False?
The thermostat should be wired in series with the automatic gas valve.
True.
Which of the following is normally open:
A. The high limit switch.
B. The fan switch[][][][][][]]
C. The low-water cutoff[][]
D. The solenoid gas valve.
B. The fan switch.
When using a combination high limit control on a forced warm air furnace, the high limit shares the bimetallic sensing device with:
A. The thermostat.
B. The safety shutoff valve.
C. The pilot solenoid gas valve.
D. The fan switch[][][][][][][][][][][][][]]
D. The fan switch.
