Nait 4Th Period Combustion Analysis And Hex

Front 1

What are the three types of combustion

Back 1

Perfect

Complete

Incomplete

Front 2

What are the 4 types of combustion air

Back 2

Primary

Secondary

Excess

Dilution

Front 3

Primary air controls

Back 3

The amount of fuel that can be burned efficiently

Front 4

Secondary air increases________ ______ by causing the fuel to completely burn

Back 4

Combustion efficiency

Front 5

Excess air is air in excess of the air which is theoretically required for combustion. The the burner will improve the mixing of

Back 5

The fuel and air

Front 6

If excess air is dramatically increased beyond what is needed the result will be

Back 6

Lower flue gas temperatures which lowers combustion efficiency

Front 7

Dilution air does not directly promote the combustion process but is used to control

Back 7

The stack effect

Front 8

Combustion efficiency is a calculated measurement of how well the appliance

Back 8

converts fuel to usable heat

Front 9

Thermal efficiency is the measurement of the effectiveness of the HEX in

Back 9

Removing heat from the fuel burned

Front 10

Annual fuel utilization efficiency (AFUE) is the true measure

Back 10

Of an appliance’s efficiency

Front 11

Input-output method is a calculation dividing the

Back 11

Output of an appliance by the input and multiplying by 100

Front 12

Flue gas temperature is the temperature of combustion gases

Back 12

As they exit the appliance

Front 13

How much oxygen is in the air

Back 13

20%

Front 14

What type of combustion is achieved in a gas burning appliance

Back 14

Complete combustion

Front 15

What are the first products produced by incomplete combustion

Back 15

Aldehydes

Front 16

Which portion of the air supply is theoretically not required for combustion

Back 16

Excess air

Front 17

Which portion of air is used to tune the burner

Back 17

Excess air

Front 18

Which efficiency rating accounts for standby losses

Back 18

AFUE

Front 19

Which fuel has a higher hydrogen/carbon ratio

Back 19

Propane

Front 20

What happens if combustion air temperature is lowered

Back 20

Combustion efficiency is lowered

Front 21

Net flue gas is determined by

Back 21

Subtracting ambient temperature for the temperature of the gases upstream of the draft control device

Front 22

What happens to the efficiency if the primary air is adjusted

Back 22

Little or no difference

Front 23

Why is it important to determine the temperature rise of a forced air furnace

Back 23

Ensures the flue gases are transferring the correct amount of heat

Front 24

How do you change the temperature rise of a furnace

Back 24

Change the speed of the blower motor

Front 25

What is the typical vent pressure of an atmospheric appliance

Back 25

-0.1wc to -0.03wc

Front 26

When conducting flue gas analysis the ultimate amount of carbon dioxide is

Back 26

12%

Front 27

Determining the content of oxygen in flue gas allows us to determine the amount of

Back 27

Excess air entering the appliance

Front 28

The formula for determining excess air is

Back 28

Back (Definition)

Front 29

What is the maximum CO exposure level in 8hr period is

Back 29

25ppm

Front 30

When testing vent pressure one opening of the draft gauge connects to the the vent and the other to

Back 30

Atmosphere

Front 31

Where should flue gas sample be taken

Back 31

In combustion chamber upstream of draft control device

Front 32

What does a very low vent draft indicate

Back 32

Appliance is grossly underfired

Front 33

What two readings are required to determine combustion efficiency

Back 33

Flue gas temp

CO2 content

Front 34

If excess air (O2) is higher than 8% you should

Back 34

Reduce the excess air

Front 35

If excess air (O2) reading is below 3.5% you need to

Back 35

Add excess air

Front 36

What is a common cause of cracks in heat exchangers

Back 36

Metal fatigue

Front 37

What must be done if a defective HEX is found

Back 37

Replace the HEX

Front 38

What heat exchangers test requires the use of a butane torch

Back 38

Sodium ion test

Front 39

If CO2 decreases, CO

Back 39

Increases

Front 40

If AFUE increases, flue gas temperature

Back 40

Decreases

Front 41

If too much air is added to the combustion zone, combustion efficiency

Back 41

Decreases

Front 42

CO2 level in flue gas should be as

Back 42

High as possible

Front 43

Why is it important to determine the amount of unburned oxygen in flue gas

Back 43

To see which side of CO2 scale we are on

Front 44

What % of O2 is best in flue gas

Back 44

Less than 8%

Front 45

How is net flue gas determined

Back 45

Flue gas - ambient air temp

Front 46

Combustion efficiency is found by using

Back 46

CO2 and net flue gas temp