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Lvl. 4 Gas - Exam #2 > J7/J8 PPT'S > Flashcards

J7/J8 PPT'S Flashcards

1
Q

Category I appliances are equipped with ______ control

A

draft

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2
Q

If you poke a hole in a category I appliance, what will happen?

A

Air will go in - flue gases won’t leak out due to the below atmospheric pressure within

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3
Q

Difference between a category I and II appliance and why are cat. II rare?

A

Category II are considered condensing appliances although they still operate with a non-positive vent pressure (negative)

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4
Q

Category III appliances operate with a _________ vent pressure

A

positive

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5
Q

Category III appliance venting flue gases will leak out if you poke a hole due to the positive pressure. True or False?

A

True

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6
Q

Are category III appliances condensing?

A

NO

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7
Q

Category IV appliances operate with a positive vent static pressure with flue loss not less than __%. It is a ___________ appliance.

A

17%

condensing

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8
Q

A vent that is too large has what effect?

A

Mixes too much dilution air with combustion products

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9
Q

Excess air dilutes & cools the gases to a point where ______ can not be created or maintained.

A

draft

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10
Q

A vent that is too small constricts the flow of gases and does not have the capacity to carry all of the combustion products outdoors. True or False?

A

True

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11
Q

Purpose of a pressure neutralization device in a fan assisted appliance?

A

To allow flue gases to be vented by buoyancy

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12
Q

Fan assist appliance regulates _________ air supply but does not affect venting pressure

A

combustion

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13
Q

Fan assist appliances are more efficient that natural draft appliances. True or False?

A

True

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14
Q

Do fan assist appliances have flow switches?

A

Yes, it proves the burner fan is operating

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15
Q

Why are fan assisted appliances more susceptible to condensation?

A

Produce lower volume and temp than draft hood equipped units

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16
Q

Vent connectors can be made of either ‘c’ or ‘b’ vent type. True or False

A

True

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17
Q

Main vent can only be of the ‘B’ type. Depending on temperatures. True or False?

A

True

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18
Q

B vent can not exceed what temperature rating?

A

470F

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19
Q

What is a major factor in creating draft?

A

Height

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20
Q

The higher the vent stack, the ________ the pressure and _______ the gas

A

lower, hotter

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21
Q

Natural draft appliances rely on _______ and ___ to create draft

A

height and TD

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22
Q

Where to find definition for Damper, Flue Damper, and Vent damper?

A

B149 code

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23
Q

Newer appliances have fans and are called “________” or “induced” draft venting.

A

forced

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24
Q

Gas appliances require a flue that has a good draft in it to get rid of products of combustion after most of the heat has been removed. True or False?

A

True

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25
Q

What is one problem with natural draft appliances? How to correct it?

A

Draft occurs even when appliances are off.

A vent/flue damper

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26
Q

There are two types of flue dampers, name them

A

Electric

Thermal

27
Q

Are electric or thermal flue dampers more common?

A

Electric

28
Q

Thermal dampers are maintenance free, do not require power, and operate automatically. True or False?

A

True

29
Q

How do thermal dampers open?

A

Bimetal mechanism that is heat sensitive

30
Q

Are thermal or electric dampers more reliable?

A

thermal

31
Q

No flue damper causes warm air to escape through the appliance. True or False?

A

True

32
Q

Flue dampers allow the appliance to hold and radiate remaining heat into the space. True or False?

A

True

33
Q

Exhaust fan dampers are normally _______ and must be proven open via a __________ switch to control the flow of flue

A

closed

proving/end

34
Q

Dilution air _______ and _____ combustion gases

A

cools and slows

35
Q

Draft hoods keep the burner at _________ pressure. Also known as ?

A

atmospheric

neutralization stack effect

36
Q

Draft hoods also provide spillage relief in case of a _________ and stops flame roll out

A

spillage

37
Q

A fan assist appliance does not develop any venting pressure. It only assists in combustion air supply. Draft still dependant on bouyancy. True or False?

A

True

38
Q

Stack effect must consider conditions such as?

A

Chimney height, TD inside and outside, wind fluctuations

39
Q

A draft regulator is also known as a ?

A

barometric damper

40
Q

A draft regulator/barometric damper is a hinged, weighted door on the _________ of the flue

A

opening

41
Q

A barometric damper/draft regulator is typically used on which type of appliances?

A

Ones that have a negative over-fire draft, such as a fan assisted burner or oil fired burner (can be modulating or on-off)

42
Q

An appliance with a barometric damper shall have a vent pressure that is?

A

below atmospheric

43
Q

Barometric dampers maintain ___________ draft in the appropriate range of the combustion chamber (below atmosphere)

A

continuous

44
Q

Neutral over-fire appliances only require a _____ _______ but negative fired appliances require a ________ _________

A

draft hood

barometric damper

45
Q

Single acting barometric dampers ___ allow spillage

A

do not

46
Q

Double acting barometric dampers ________ spillage

A

allow

47
Q

What is the purpose of a double acting draft regulator/barometric damper?

A

to allow spillage into the mechanical room until the stack warms enough to sustain the draft

48
Q

Single acting is required on oil fired burners and incinerators. True or False?

A

True

49
Q

A draft regulator shall not be used as a substitute for a draft hood. True or False?

A

True

50
Q

Most installations are equipped with ______-acting barometric dampers, EXCEPT for?

A

double acting

incinerators and oil fired burners

51
Q

Where is a barometric damper installed?

A

In the flue between the appliance and the chimney

52
Q

Barometric dampers should, but not always, be installed in the appliance ______ not the _______ ______

A

vent

common vent

53
Q

The barometric damper is set for the desired draft conditions using ______ and adjustment screws

A

weights

54
Q

If the draft inside the chimney is
_________ than the set-point of the
damper, the damper will ______ and
allow air from the boiler room inside
the chimney, rather than stealing heat from the appliance.

A

greater

open

55
Q

Barometric damper weight added affecting draft

  1. No weight = ______ draft
  2. Some weight = _______ draft
  3. Most weight = _______ draft
A
  1. fully open, least draft (slow)
  2. mid open, increase draft (faster)
  3. closed, high draft (fastest)
56
Q

What tools can be used to measure draft? (3)

A
  1. draft gauge
  2. magnahelic
  3. digital manometer if scale is small enough
57
Q

Normally we measure draft in two locations. What are they?

A
  1. over the fire or in combustion chamber
  2. close to the flue before the damper
58
Q

Depending on the appliance
manufacturer, it may be critical to
measure the draft in the __________ ________

A

combustion chamber

59
Q

If a test port is not available the
draft measurement can often be taken through a ____ port at the burner or on the combustion chamber

A

site port

60
Q

The draft setting is set per?

A

manufacturers documentation

61
Q

If the draft is too low, _____ some weight to the damper chain (this will choke dilution air and increase the draft

A

add

62
Q

If draft is too high, ______ some weight, this will increase dilution air and decrease the draft

A

remove

63
Q

Check the draft at the ________ to measure over-fire draft in the __________ chamber. Then you can adjust the damper accordingly

A

burner

combustion chamber

Lvl. 4 Gas - Exam #2 (9 decks)

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