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57 Cards in this Set
- Front
- Back
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What is the minimum efficiency for gas-fired appliances |
80% |
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What does having too much air intake to the burner result in? |
Oxidizing flame/flashback |
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What is the tube called that mixes the air and fuel? |
Venturi Tube |
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What should you do if an appliance is recieved with damages? |
Request immediate inspection and report damage to transporter |
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What are the minimum return air temperatures on a forced air furnace? |
55°F - 80°F |
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Why is using a central hearing appliance not recommended for temporary heat? |
Could expose heat exchanger to low return air temps, or dirty and corrosive air |
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Why must the burner door be in place when checking quality of flame? |
Excessive air could lead to the flame indicating there is further adjustment needed |
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What would an orange colour in the flame indicate? |
Dirt or dust from the combustion air |
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Why is a yellow flame a bad thing? |
Not all the fuel is being burned, could lead to dangerous chemicals going into the air through incomplete combustion |
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What is an additional concern when replacing components on a hot water boiler? |
Make sure the hit water under pressure isn't purged accidentally, dangerous to anyone in the immediate vicinity |
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What 3 things must be in place before combustion will occur? |
Air, fuel, ignition |
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What is combustion? |
Rapid oxidization of fuel by combining it with oxygen in the presence of heat |
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What are the products of normal combustion? |
CO2+H2O+N+O2 |
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What is Flame Inpingement? |
Burner flame coming too close or touching a surface which cools the flame |
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What is the minimum ratio of combustion air to fuel for full conversion from fuel to heat? |
1CF of combustion air per 100BTU of potential heat |
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How does Carbon Monoxide decrease appliance efficiency? |
CO lowers heat output through incomplete combustion, which leads to soot layering on the heat exchanger |
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What would indicate a burner is producing carbon Monoxide? |
Yellow flame or soot near the burner or on the heat exchanger |
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What is a Monoport Burner? |
An open tube, single port inshore burner with non-adjustable air inlet. Developed for induced draft appliances |
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What kind of burners are used on water boilers? |
Multi-ported tube/ribbon burners |
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What kind of burner ALWAYS uses a venturi tube? |
Atmospheric burners |
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What is one way an Induced Draft Burner may be different from an Atmospheric Burner? |
Induced draft burners often have non-adjustable primary air openings |
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Why do induced draft burners have larger ports than the similar natural draft burners? |
Larger ports permit the induced draft fan to create sufficient air flow |
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What types of flame can be achieved by adjusting primary air inlets? |
Carbonizing, neutral, oxidizing |
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Why is air and fuel pre-mixed before ignition? |
Increased flame temperature and reduction of CO produced |
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What is a Linting Burner? |
A natural draft burner |
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What does an ECO do on a storage type water heater? |
If it is overheated, the ECO will interrupt power to the gas valve |
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How is air pre-mixed in an induced draft burner with not venturi tube? |
Draft fan pulls air into burner inlet with enough speed to create turbulence for mixing |
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What is a catalytic screen used for in some burners |
Reduces NOx emissions |
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What is the first recommended check when lighting a new appliance for the first time? |
Smell for fuel around the appliance |
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An Inspirated burner has that name because? |
Most of the air for combustion is entrained with the fuel prior to ignition |
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How are the 2 categories of burners distinguished? |
By the way The fuel/air is supplied to the combustion chamber |
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Aspirated burners require what? |
A forced draft fan |
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The heat exchanger in a mid-efficient appliance has restricted flow because? |
To allow a high percentage of heat to be extracted from the combustion products |
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What does the inducer fan motor do in a mid-efficient appliance? |
Draws products of combustion through heat exchanger |
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Why do I shot burners have a deflector plate on their outlet? |
To refuse flame impingement im |
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What term is used to best describe overall efficiency of an appliance |
Annual Fuel Utilization Efficiency |
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How was the efficiency of central heating appliances increased to mid-efficient? |
The heat exchanger was redesigned |
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How is the efficiency of a furnace increased to high-efficient? |
The water vapour in the flue gases condense |
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What device proves the inducer fan is moving air? |
The pressure switch |
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What catagory would an appliance with a draft hood be? |
Catagory I |
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What kind of pressure is in the vent of a Category I appliance?
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Non-possitive |
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What category of appliance condenses water vapour in the flue gas?
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Category IV
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What type of vent would normally be used for a category I appliance?
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B-Vent
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A forced draft burner utilizes a fan in order to:
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Overcome the restriction of the appliance and the burner
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What combustion chamber design is not suitable for conversion?
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Revertable
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Why does an induces draft fan have a longer operation cycle than the burner? |
To ensure that the combustion chamber and the heat exchanger are clear
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Approx. what percentage of the air is Nitrogen?
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80%
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What type of combustion should be achieved in gas-burning appliances?
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Complete combustion
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Which portion of the air supply is required for complete combustion?
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Excess air
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What can you smell in combustion by-products?
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Aldehydes
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What happens to the efficiency of an appliance when the primary air shutters are adjusted?
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Little to no difference in efficiency
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Where should the flue gas sample be taken from?
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In the combustion chamber upstream of the draft control device
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Describe what "inspirated burner" means
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Most of the air for combustion is entrained with the fuel prior to combustion
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What does the inducer fan on a mid-efficient appliance do?
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Draw products of combustion through heat exchanger
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Why do inshot burners have a deflector plate on their outlet?
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So the flame does not impinge on the back surface of the combustion chamber
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What does a mid-efficient furnace with staged firing require?
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An induced draft fan capable of operating at different speeds
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