Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Lvl. 4 Gas - Exam #2 > J6 PPT 1-4 > Flashcards

J6 PPT 1-4 Flashcards

1
Q

In a passive air supply system, there are no mechanical devices used to bring the air from outside to inside. True or False?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Passive air supply systems use dampers, grills and louvred vents to bring outside air in for combustion. True or False?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Ducting a fresh air supply near the the furnace or boiler burner provides all combustion air and _________ air if necessary.

A

Dilution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

A hole in the wall may be used as fresh air instead of ducting providing the appliance is close enough and it complies with 8.3.1 (d). True or False?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Mechanical air supply is based on ____cuft per 1000btuh which is perfect stoichiometric combustion

A

30cuft per 1000btuh

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Air can be split into 3 categories. What are they?

A
  1. Combustion
  2. Dilution
  3. Ventilation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The three parts to combustion air are?

A
  1. Primary
  2. Secondary
  3. Excess
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the portion of air supplied to the initial stages of combustion and controls the rate of combustion?

A

Primary air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Primary air is ___ of stoichiometric combustion air and ____cutft per 1000btu’s

A

1/3

3.33

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the portion of air supplied for the intermediate and final stages of combustion and controls combustion efficiency?

A

Secondary air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Secondary air is ____ of stoichiometric combustion air and ____cuft per 1000btu’s

A

2/3

6.67

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the extra portion of air supplied to the combustion zone that is not required for complete combustion?

A

Excess air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Atmospheric appliances require ___% excess air. (50% of theoretical combustion). Therefor they require __cuft per 1000btuhs.

A

50%

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Power burners require ___%-___% excess air or 2.5 cubic feet per 1000btuh

A

20-25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Is dilution air apart of the combustion process?

A

NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is dilution air required?

A

To slow and cool flue gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Do all appliances require dilution air?

A

Only if they have draft control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The ambient air that is admitted to a
venting system at the draft hood, draft diverter, or draft regulator is known as?

A

Dilution air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Do fan assist appliances require dilution air?

A

NO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Dilution air is ___cuft per 1000btu

A

15cuft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe ventilation air

A

Air supplied by an opening or exfiltration to a space with an appliance to replace exhausted air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Excess air _______ complete
combustion.

A

ensures

23
Q

High efficiency appliances require about ___% excess air

A

25%

24
Q

Excess air is the air required ______ the amount needed for stoichiometric combustion

A

ABOVE

25
Q

__________ appliances require 50% excess air added to stoichiometric air requirements (5ft per 1000btuh)

A

Atmospheric

26
Q

Name two draft control devices?

A
  1. Draft hood
  2. Barometric damper (draft regulator)
27
Q

Name three appliance configurations with no draft control

A
  1. Fan assist
  2. Forced draft
  3. Induced draft
28
Q

Dilution air is added downstream of the heat exchanger at the draft control device. True or False?

A

True

29
Q

Dilution air is not part of the combustion process. True or False?

A

True

30
Q

Name three types of air duct covering/screens?

A
  1. Grill
  2. Louvre
  3. Screen
31
Q

Grills/Louvres are usually made of galvanized iron, copper, aluminum or other rust-inhibited materials. True or False?

A

True

32
Q

Air grills have efficiency ratings so they must be increased to allow for proper airflow. True or False?

A

True

33
Q

Rectangular and round duct can come in sizes from __in to ___in

A

3in to 41in

34
Q

Type of ducting material also determines _______

A

sizing

35
Q

Name the two types of make-up air heaters. They operate generally in the same way.

A

direct fired

indirect fired

36
Q

What are make-up air heaters designed to do?

A

Replace exhausted air at the desired temperature

37
Q

Make-up air units have ___________ gas valves

A

modulating

38
Q

The discharge air nozzle on a make air unit is adjustable. True or False?

A

True

39
Q

Make up air units have two gas manifolds. Name them.

A

Main gas manifold

Pilot gas manifold

40
Q

Velocity of a makeup air air steam?

A

2,500 - 3,500 fpm

41
Q

Make-up air combustion system utilizes a ______- mixing type of line burner, in which a circulating air stream supplies all all air needed

A

nozzle

42
Q

At which pressure is raw gas typically fed directly into the burner ports on a direct fired make up air?

A

5” w.c

43
Q

For a DFMA, the fast air stream provides means of mixing the air and gas, as determined by the shape and size of holes in the baffles. True or False?

A

True

44
Q

Proper combustion is achieved over a wide firing range, up to __:_ turndown ratio

A

30:1 turndown ratio

45
Q

The air flow through the heater must be straight and have sufficient velocity to maintain adequate ________ and burner capacity within the space allowed

A

turndown

46
Q

Where is the blower located on a make-up air?

A

downstream of the burner (negative side)

47
Q

What is the purpose of having the blower on the negative side of a makeup air?

A

The pull through method helps to avoid airstream stratification, where the blower mixes excess air and combustion products

48
Q

Any of these malfunctions will cause a burner safety shutdown (manual reset)
- pilot fails to ignite
- loss of flame after ignition
- high discharge temperature
- low cabinet temperature — outdoor
units only
- high air velocity through the profile
plate
- low air velocity through the profile
plate

A

True

49
Q

Fan assisted BURNER overcomes the resistance of the burner only. True or False

A

True

50
Q

Is a fan assisted BURNER equipped with a draft control?

A

Yes, fan only overcomes burner. Remaining flue rises out. Requires draft control and dilution air.

51
Q

Fan assisted APPLIANCE has a draft through the entire appliance and is not equipped with draft control. True or False

A

True

52
Q

Does a fan assisted appliance require dilution air?

A

No, because there is no draft control

53
Q

Draft hood requires?

A

30cutft of air

15 dilution
10 combustion
5 excess

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

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions