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42 Cards in this Set
- Front
- Back
What is the ultimate CO2 in a flue gas sample? |
12% by volume |
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When the production of CO2 diminishes, what happens to the co production |
Increases |
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What will happen to the flue gas temperature if the appliance afue efficiency increases? |
Decreases |
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What will happen to combustion efficiency if too much air is added to the combustion Zone? |
Decreases |
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When testing for CO2 in a flue gas sample, what kind of results do we want? |
The percentage of CO2 in the sample should be as high as possible |
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Why is it important to determine the amount of unburned oxygen in a flue gas sample? |
To determine which side of the ultimate CO2 scale we are on |
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What result would be best when determining the O2 percentage in the flue gas? |
The percentage of o2 in the sample should be low. Less than eight percent |
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How is net flue gas temperature determined |
Subtract ambient temperature from the flue gas temperature |
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What would be the normal draft in the vent for a category 1 draft Hood Appliance? |
About 0.03 in water column negative pressure |
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What results are required to determine the combustion efficiency of a gas-fired Appliance? |
The CO2 and the net flue-gas temperature |
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If oxygen from the air burns in the combustion process, why would oxygen be present in the flue gas? |
This is from the unused excess air |
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Common scent based test used to find a crack in a heat exchanger |
Sulfur test or Wintergreen test |
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When the blower motor comes on normally stable Flames now become unstable and blow all over the place what is the most likely cause? |
Cracked heat exchanger |
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What must be done with the furnace in the house that is found to have a cracked heat exchanger? |
The heat exchanger must be replaced |
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What is the biggest concern if a furnace and a house has a cracked heat exchanger? |
Possibility of flame rollout and eventual carbon monoxide production |
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Primary air |
Provides percentage of the combustion air but more importantly, it controls the amount of fuel that can be burned efficiently |
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Secondary air |
Increases combustion efficiency by causing the fuel to completely burn |
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Do power burners require secondary air |
No |
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Excess air |
Is supplied to the combustion Zone is air an excess of the air which is theoretically required for combustion |
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Dilution air |
Does not directly promote the combustion process but is used to control the stack effect and reduce the probability that moisture formed by the combustion of fuel will condense in the venting system |
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What flame characteristics should a category 1 Appliance have |
Slightly carbonizing |
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Water heater burner flame should have what characteristics |
Neutral |
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Range top burner flame characteristics |
Slightly oxidizing |
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What type of combustion is achieved in a gas burning Appliance |
Complete combustion |
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What are the first products produced by incomplete combustion |
Aldehydes |
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Which portion of the air supplies theoretically not required for combustion |
Excess air |
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Which portion of the Air Supply is used to tune the burner |
Excess air |
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Which efficiency rating accounts for standby losses |
Annual fuel utilization efficiency or afue |
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Which of the following fuels has the highest hydrogen to carbon ratio, coal, wood, heating oil, propane gas? |
Propane gas |
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What happens to the efficiency of an appliance if the temperature of the combustion air is drastically lowered? |
Decreased |
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What happens to the efficiency of the appliance if the primary air shutter is adjusted? |
Little to no difference |
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What is the importance of determining the temperature rise of a forced air furnace? |
Ensures that the flue gases are transferring the correct amount of heat |
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How is the temperature rise on a forced air furnace changed? |
Circulating air blower speed is changed |
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What is the importance of determining the oxygen content of the flue gas |
Allows the amount of excess air entering the appliance to be determined |
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What number do you multiply an oxygen reading by to get the percentage of excess air |
5 |
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Maximum carbon monoxide exposure level for an 8 hour time frame |
25 PPM |
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When testing the pressure in the vent, one opening of the draft gauge connects to the vet. Where does the other opening connect? |
Atmosphere |
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Where should the flue gas sample be taken from |
In the combustion chamber Upstream of the draft control device |
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What does a very low vent draft indicate |
The appliance is grossly under fired |
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What adjustment is required for an appliance with a CO2 reading of 7% and an O2 reading of 12%? |
Excess air should be reduced |
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What is a common cause for cracks in heat exchangers |
Metal fatigue due to heat / cool Cycles |
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What heat exchanger test requires the use of a butane torch |
The sodium ion test |