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20 Cards in this Set
- Front
- Back
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What is one property of heat energy |
It seeks to move from hot to cold |
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What is thermal resistance also known as or called |
The R value of the material |
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The R value of various construction materials are added up to determine what |
The total thermal resistance per square foot |
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What would happen if equipment was sized for the lowest recorded temperature |
The equipment would be oversized and inefficient because these weather extremes only occur a few times a year |
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What will designing to a heat load insure |
A comfort level will be maintained |
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How must an air delivery system be designed |
To properly deliver the air into the Room without creating uncomfortable drafts |
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When do heating systems perform well |
In a perimeter distribution system |
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In a perimeter system Where do the return air grilles perform best |
low on inside walls |
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At least how many return air grills must be installed on each floor level of The home |
At least one per level |
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What are supply air duct runs sized to deal with |
The CFM carried, the distance from the furnace, number of fittings from the furnace to supply air register |
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What is aspect ratio |
Ratio of one side of a duct to the other, longer dimension divided by the shorter dimension Should not be more than 4 to 1 |
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What must your furnace Blower overcome |
Resistance created by friction as the air is pushed through the ducts |
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What happens when conditioned air leaks from a duct system |
Both energy for heating or cooling and energy for moving the air are lost |
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What is equal friction |
CFM = area times the velocity |
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What is the duct sized to maintain |
The same friction loss per 100' through the entire system |
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What must be done to maintain static pressure in a supply trunk |
A Reduce or is needed after approximately every 6 to 8 runs off the trunk |
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What is a good design also require |
Dampers in each branch line to allow system to be balanced |
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How can friction loss in dynamic loss be Reduced |
Avoid turns or size changes whenever possible Using gradual turns or slopes if changes are necessary, And supply and return square throw elbows must have turning vanes |
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What are more effective single thickness turning vanes or double thickness |
Single thickness |
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What centerline radius should be used for radius throat elbows |
1 1/2 Times the width of the cheek , this is the same as a throat radius = the width of the cheek |
