gas exam
73, a pilot with primary air is called
An aerated pilot
As more excess air is added
Co2 goes down, o2 goes up
38. improper pressure can have what negative effect?
Co2 production, rollout and shorten unit's life
gas fired refrigerators must incorporate what safety?
High limit and CO detector
75, this type of furnace has its blower section lateral to (beside) the heat exchanger
Low boy, horizontal furnace
84. Select the example that best describes how a lower heated medium temp affects an appliances natural draft venting system
Low supply air temperature in a furnace absorbs too much of the flue gas heat, decreasing flue gas temp and reducting draft.
a forced draft motor Is upstream of the combustion zone, creating a negative pressure in the appliance Is downstream of the combustion zone, creating a positive pressure in the appliance Is part of the burner and affects combustion air, not the venting
*None of the above
an inducer motor Is upstream of the combustion zone, creating a negative pressure in the appliance Is downstream of the combustion zone, creating a positive pressure in the appliance Is part of the burner and affects combustion air, not the venting
*None of the above
95, every chimney, or A vent, must have
A clean out
101, which of the following statements is correct?
None of the above
80. a natural draft burner system operate because
None of the above
what is the purpose of the appliance regulator?
None of the above
the purpose and function of a regulator is
Reduce and maintain pressure appropriate to the appliance
35, what could burnt wiring found during an inspection indicate?
Roll out, a corrosive environment, and excessive current/resistance
39, the following in NOT a type of regulator
Rotary style
72. a burner that supplies air under pressure and gas at atmospheric pressure would use what kind of regulator?
Zero governor
Define primary air
air that is mixed with the fuel prior to combustion
13, where electrical current passes through an element which heats to ignite the gas is commonly referred to as
HSI
Diaphragm meters
Have "bellows", as one fills the other empties
List the 3 common purposes of a burner
Mix fuel and air, ignite it, remove products of combustion
22. what causes the contacts on a pressuretrol to open?
Setpoint
44. lock up is
The amount of pressure above setpoint where the regulator shuts closes
18. a flame rectification system uses what as a conductor?
The flame
74. flame rod rectification uses what to get DC?
The flame
81, natural draft venting systems operate because
The higher temp flue products create a positive pressure and rise towards the lower pressure area
34. when making a conversion from one gas to another, what must be noted on the rating plate?
The new type of gas
47, setpoint, in reference to a regulator pressure relief, is
The point at which the relief device begins to open
46 .when a servo regulator is fully closed, it is because:
The pressure over and under the diaphragm are the same
7, explain turn down ratio
The ratio to which a burner may be throttled or modulated...........
83, in induced draft system where the motor is in the appliance has its venting structure
Under position pressure
30. how does a duct heater differ from a unit heater?
Unit heater do not have ductwork
61, a direct operated pressure relief senses
Upstream pressure
23, a probe type low water cut off uses what as the conductor
Water
70. a high stack temperature indicates
We aren't effectively transferring energy to our medium
77CO2
...Is a non-toxic, asphyxiating gas that is formed during combustion
59, a natural gas regulator vent line NOT using a certified over pressurization device must be how far from a mechanical air intake?
10 ft
56. the maximum gas pressure allowed into the boiler room of a commercial building is
20 psig
3, Define secondary air
Air that is mixed with the fuel at the point of combustion
17, a thermistor is a
Device that has its resistance change based on temp
69, as more excess air is added
Efficiency increases
98. a mid effiecient gas fired recessed wall furnace would use which of the following venting
BW vent
49, a typical service regulator has what kind of relief?
Internal
58. the venting of a pressure control device shall be of sufficient size as to not cause impedance upon the:
Regulator
24. roll out differ from high limits on account that they...
Roll outs must be manually reset and high limits are automatic
48. a direct acting relief
Senses upstream pressure and relieves top atmosphere
63, if the relief valve setpoint is set lower than the regulator lockup pressure
The relief valve will never close
33, when making a conversion from LP to NG, the orifices will need to be.....
The same, but the pressure will need to change as NG operates off 7.0" WC and LP off 11.0" WC
29, what is the purpose of an expansion tank?
To allow for the expansion of water in a boiler loop
78. as condensation occurs in an appliance, what type of acid may form?
Carbonic
Define atmospheric burner
no mechanical means of adding combustion air
28. what is a "low boy" furnace?
Burner section is beside the blower compartment
87, a draft hood
Ensures excessive air is not drawn through the burner
79, combustion products do not include what
Excess air
85, select the example that best describes how excess air affects an appliances natural draft venting system
Excess air decreases flue gas temperature, increases the flue gas flow rates
86. a draft control device is used to limit draft because
Excessive draft can cause high flue gas rates and decrease efficiency
103, condensation forms when
Excessive heat is absorbed from the products of combustion, causing the vapour to recondense and form H2o
What is one main difference between a fan assist system and a power burner?
Fan assist systems are downstream OF COMBUSTION CHAMBER ......
a fan/limit control has 3 sets of contacts. They are what in correct order
Fan off, fan on, high limit
62. the set point of an internal relief valve is adjusted by:
It is not adjustable
15, the "bulb and bellows" flame sensing device relies on the expansion of what in the bulb?
Liquid
8. what is a nozzle mix burner
Primary air and fuel is mixed at the nozzle under pressure
10. the following type of pilot system would employ a means of verification prior to ignition
Proven type
66. we provide excess air to the combustion process to ensure:
That we have complete combustion
19, flame is proven in a rectification system because
The conversion of AC to DC
65, if vapour is drawn out of a propane tank
The decrease in pressure lowers the boiling point of the liquid, which then vaporizes and builds pressure
91, with a single pipe induced draft appliance, if the pressure indoors becomes excessively negative
The venting action could be reversed, causing spillage
14. the coefficient of expansion of a metal is its
Its calculated rate of expansion in change of temp.
43, the spring is
An opening force
31, what device maintains setpoint in a steam boiler
Pressuretrol
55, in a repair garage, how far off the ground must the source of ignition be?
54" (4 ft and half)
54. a unit 400k BTU or less that is certified to be installed on a non combustible floor may be installed on a combustible floor provided that its masonry units extended
6" beyond the sides of the appliance
9, the following type of pilot would have a primary air opening built into it
Aerated
5, define premix burner
Air and fuel are mixed mechanically prior to combustion
102. direct vent systems
Also called sealed combustion, also called 2 pipe, and are unaffected by indoor pressure changes
93, which of the following is a logical sequence of operation for an induced draft furnace?
Call for heat, inducer motor starts, pressure switch closes, ignition device energizes, gas valve energizes
71, a burner that supplies air under pressure and gas at atmospheric pressure is called a
Aspirator burner
97, a standard mid-efficiency gas fired appliance that relies on natural draft venting would use what type of venting material?
B vent
100. a gas fired furnace with a forced draft motor in the appliance would use which of the following venting materials?
BH vent
99, a gas fired furnace with an inducer motor in the appliance would use which of the following venting materials?
BH vent
Which of the following materials may NOT be used in a gas piping or tubing system?
Brass
45, a balanced regulator is designed to
Buffers high inlet pressure swings
51, meter and regulator installations shall be accordance with
CSA Z662
52. the installation of gas burning appliances and supply piping in mobile homes shall be in accordance with
CSA z240.4.1
76. due to the high input and low inlet water temp., what is a large concern with pool heaters?
Condensation
40. what is the purpose of a line regulator?
To reduce building line pressure even further
96. why are chimney liners used
Flue gases from natural gas appliances are lower temp, requiring smaller venting
12. the source of ignition is present during the entire call for heat is the definition of
Intermittent ignition
88. a barometric damper
Is used on systems that maintain a negative pressure over burner
42. the four common elements of a regulator are:
Measuring element, orifice, spring, and vent
11, define Piezoelectric
Mechanical force is applied to a substance which generates electricity when compressed/deformed
57, when a line pressure regulator is required and the inlet supply pressure to the regulator exceeds. 0.5 psig, it shall be of the:
Positive shut-off type
50. a monitoring system
Two regulators in series, both sensing downstream pressure at roughly the same point
92. an induced draft system where the motor is at the termination has its venting structure
Under negative pressure
16. if the flame goes out, how does a thermocouple system stop the flow of gas?
With no flame, it means of electrical generation is gone the solenoid disengages and the flow of gas ceases.
