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Period 2 - SAIT > Heating Test > Flashcards

Heating Test Flashcards

1
Q

What are the mandatory requirements for rating plates on a gas furnace? (9)

A
  • certification agencies stamp
  • type of fuel
  • altitude approved for
  • max input rating
  • max inlet pressure
  • manifold pressure
  • electrical rating
  • Manufature name
  • model number
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2
Q

What is optional requirements for a furnace rating plates?

A
  • orifice
  • output
  • serial number
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3
Q

What are the installers responsibilities (3)

A
  • ensure the appliance is in safe working order
  • instruct the user in the safe and correct operation of equipment installed
  • ensure manufacture instructions supplied are left with the user
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4
Q

Who is considered the installer?

A

the last person to work on the appliance

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5
Q

What is the purpose of a gas burner?

A
  • deliver a gas and Air mixture to the combustion zone for ignition
  • mixes the gas and Air together for ignition, proper adjustment is essential
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6
Q

What are the two types of burners?

A
  • atmospheric burners
  • forced draft/power burners
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7
Q

What is the difference between an atmospheric burner and a forced air/power burners?

A
  • atmospheric burners rely on difference in atmospheric pressure for combustion
  • forced draft or power burners uses a mechanical device (fan) to deliver air for combustion
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8
Q

What is the Venturi Principle?

A
  • As the gas stream comes through the orifice, air is drawn in and through the primary air openings into the mixer head
  • the gas mixes with the fuel in the mixing tube (Venturi)
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9
Q

What is the calorific value and Air to gas ratio for natural gas?

A
  • 1,000 BTU/cuft
  • 10:1 ratio
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10
Q

What is the calorific value and Air to gas ratio for propane?

A
  • 2,500 BTU/cuft
  • 24:1 ratio
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11
Q

What is a non-aerated burner?

A
  • luminous
  • gas is supplied to the combustion area without being mixed with air before it is ignited
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12
Q

What is an aerated burner?

A
  • Bunsen
  • the air mixed with the gas upstream of the point of ignition
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13
Q

How are burners categorized?

A

by how the air is mixed with the flame

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14
Q

What is an oxidizing flame?

A
  • large amounts of primary air
  • hard, sharp flame
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15
Q

What is a neutral flame?

A
  • medium amount of primary air
  • medium sized flame
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16
Q

What is a carbonizing or carburizing flame?

A
  • small amount of primary air
  • soft, large flame
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17
Q

What is in inshot burner

A

Horization manner

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18
Q

What is an upshot burner

A

Largely verticle

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19
Q

What are causes for a yellow tip flame?

A
  • not enough air/airflow
  • too little primary air
  • primary air openings clogged
  • burner ports blocked
  • misaligned or dirty orifices
  • blocked flue
  • orifice too large
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20
Q

What are the causes for a lifting flame?

A
  • too high velocity
  • too much primary air
  • burners overfired
  • orifice too large
  • orifice partially blocked
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21
Q

What are the causes for a waving blue flame?

A
  • draft/air blowing on burner
  • excessive draft around burner
  • cracked heat exchanger
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22
Q

What are the causes for main burner flame to be too large?

A
  • too much gas
  • burners are overfired
  • defective regulator
  • burner orifice too large
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23
Q

What are the causes for flashback?

A
  • not enough gas pressure
  • too much primary air
  • burners underfired
  • one orifice too large or too small
  • gas valve leaking
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24
Q

What are the causes for a noisy flame?

A
  • too high velocity
  • too much primary air
  • pilot overfired
  • burr in orifice
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25
Q

What would be considered a normal burn? ““hint: inches/second)

A

when gas/Air mixture speed is at 26”/second

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26
Q

What is considered a lift off burn? **hint: inches/second

A

when gas/air mixture speed is at 36”/second

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27
Q

What is considered a flashback burn? **hint:inches/second

A

when gas/air mixture is at 24”/second

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28
Q

What are pilot and pilot burners used for?

A

to effectively ignite main burners on appliances

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29
Q

What are the four main categories of pilot burners?

A
  • continuous
  • expanding
  • intermittent
  • interrupted
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30
Q

What is a continuous pilot burners?

A

standing pilot, 24hrs a day

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31
Q

What is an expanding pilot burners?

A

hybrid of a standing pilot, pilot gas supply is increased to effectively light the main burner

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32
Q

What is an intermittent pilot burners?

A

only ignited when there is a call for heat. remains on during the call for heat

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33
Q

What is an interrupted pilot burners?

A

only ignited when the is a call for heat. extinguished once main burners is lit

34
Q

What is direct ignition?

A

ignites by direct spark or hot surface ignition

35
Q

What are the three main types of pilot burners

A
  • aerated
  • post aerated
  • non aerated
36
Q

What is the main objective when igniting the main burners?

A
  • achieve the bluest flame possible and avoid soot/carbon residue
37
Q

What is an aerated pilot

A
  • AKA Bunsen or linting pilot
  • primary opening is susceptible to blockage by lint or dust
38
Q

What are non aerated pilots?

A
  • AKA non primary or non linting pilots (used on gas dryers)
  • slight yellow flame as there is no primary flame
39
Q

What are post-aerated pilots

A
  • AKA incinerating or target pilots
  • commonly used in residential and light commercial
  • similar to aerated pilots; has primary air openings which burns off lint or dust in the air
40
Q

What is a safe hookup (proved pilot)

A
  • AKA non 100% shut off
  • automotive safety control is limited to the main burner
  • on pilot outage, the main burners gas is shut off by the safety control but pilot gas is not
41
Q

What is a 100% safe hook up (pilot proved)

A
  • most appliances are of this type
  • the automatic safety control shuts off the gas supply to both the main burners and the pilot in case of pilot outage or safety control failure
42
Q

What is the Seebeck effect?

A

when two different metals joined at both ends and heated at one ends creates a small amount of DC current flow
- measured in Millivolts DC

43
Q

What are thermopiles?

A
  • AKA powerpiles
  • several thermocouples linked in series
  • replaces the same millivolt output that was removed
  • 325 to 750mv DC
44
Q

What is the power unit?

A

energized by the thermocouple or thermopile and holds open the safety gas valve or safety switch closed
- always replace with same millivoltage output

45
Q

When installing a pilot

A

it should not be mounted too high above or too low beneath the burner….just right

46
Q

How to ensure most amount of voltage is produced by the thermocouple?

A

ensure there is a difference between the hot and cold junctions
- heat the top 3/8” to 1/2” tip

47
Q

What to avoid when installing the thermocouple?

A

BENDING!! avoid bends closer than 1” and never closer than 1/2”

48
Q

When testing thermocouples, what rating should you get for an open and closed circuit?

A

open circuit: 17 - 32mv DC

closed circuit: 8 to 17mv DC

49
Q

When testing thermocouples, what ratings should you get for drop out range and turn down test?

A

Drop out range: 0.75 - 6mv DC

Turn down test: 2mv DC

50
Q

What is the typical thermocouple testing?

A
  • between 25-30mv DC
51
Q

What are the 3 types of orifices

A
  • fixed orifice/plug orifices
  • adjustable orifice
  • cap/universal orifices
52
Q

What is the most common type of orifices?

A
  • fixed/plug orifice
53
Q

What is an adjustable orifice?

A
  • used one older gas ranges, some industrial burners
54
Q

What are cap/universal orifices?

A
  • also used on fuel appliances that need to be site adjusted to burn propane or natural gas
55
Q

What does an orifice do?

A
  • controls the volume of gas delivered to the burners
56
Q

How are orifices sized?

A
  • DMS (Drill manufacturers Standard)
  • the larger the DMS number, the smaller the orifice size
57
Q

What can cause problems with orifices?

A
  • correctly installed orifices present no problem
  • problems occur when changing fuels (natural gas to propane) or altitude (sea level to 4500’)
58
Q

What MUST be considered when drill orifices?

A
  • always drill 2 sizes smaller than desired; adjust with a reamer
59
Q

What must be determined when sizing and orifice and calculating input rates?

A

BTUH rate must be determined first

60
Q

What is orifice interpolation?

A

finding the BTU value between two given pressures on the chart

61
Q

Why altitude adjustments are needed when sizing an orifice?

A
  • altitude affects combustion due to air pressure
  • air is thinner at higher altitudes therefore gas volume must be reduced
  • appliances are required to have altitude ratings marked on the rating plate
62
Q

What is considered sea level and high altitude elevations?

A

sea level = 0’ to 2000’ elevation
high altitude = 2000 to 4500’ elevation

63
Q

When installing appliances at high altitude, what must be done? At above 4500’

A

at high altitude, derated by 10%

above 4500’, derated by additional 4% per 1000’ elevation rise

64
Q

What is the purpose of a regulator?

A

reduce and maintain a set pressure while compensating for demand changes

65
Q

How does a regulator work?

A

it uses a fixed orifice opening for the restricting element, a diaphragm for the measuring element and a spring for the loading element

66
Q

What are restricting elements in a regulator?

A
  • orifices and the valve plug
  • the restriction limits the amount of maximum flow capacity through the regulator
  • the office is fixed while the valve plug moves
67
Q

What is the measuring element in a regulator?

A
  • the diaphragm
  • made of neoprene
  • attached to the valve stem and measures outlet (downstream) pressure
68
Q

What is the loading element in a regulator?

A
  • the spring/weight
  • by increasing or decreasing the spring tension acting on the diaphragm, you can raise or lower the outlet pressure
  • dial in (clockwise) to increase
69
Q

What is a regulator vent?

A
  • (spring/weight)
  • atmospheric pressure must be allowed to and from the spring housing
  • terminate outdoors (unless limiting)
70
Q

What are internal relief devices in a regulator?

A
  • over pressure devices to relieve excess gas pressure
  • if outlet pressure rises too high, excess pressure is vented to outdoors
71
Q

What are leak limiting controls on a regulator?

A
  • ball check leak limiting devices
  • restrict max amount of gas vented (2.5cuft/hr for natural gas)
  • if diaphragm ruptures ball check closes
72
Q

What is a low pressure trip in a regulator?

A
  • a low pressure trip activates if outlet pressure becomes too low
  • reset by pulling plunger underneath dust cap
73
Q

What are some causes for a low pressure trip on a regulator? (3)

A
  • low inlet pressure,
  • rupture in outlet piping, - improper operation of gas equipement
74
Q

What are the different types of regulators?

A
  • service regulators
  • system regulators
  • appliance regulator
  • servo regulators
75
Q

What is a service regulator

A
  • service to a building (only utility company can work on)
76
Q

What is a system regulators?

A
  • used to decrease building pressure before going to appliances
77
Q

What is an appliance regulator?

A
  • found in appliances
78
Q

What is a servo regulator?

A
  • combination gas valve
79
Q

How many regulators is used on a propane system?

A

2 regulators or a dual stage regulator to achieve manageable pressures

(1 high pressure regulator at the tank = 5 to 10 psi and 1 low pressure regulator outside the home = 11 to 14 inches w.c)

80
Q

What is the code for venting a regulator?

A
  • low pressure trip or relief valves must not be isolated or bypassed, no plugs of caps on the vent terminal
  • vent termination must be at least 3’ from a dryer vent

Period 2 - SAIT (3 decks)

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