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16 Cards in this Set
- Front
- Back
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Which of the following factors affects a customer's level of comfort? |
Temperature, humidity, air movement, air cleanliness, fresh air ventilation |
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A cooling load calculation estimates the sensible heat gain of a structure. The maximum sensible capacity of a cooling-only system should be within ________% of this calculated value. |
+15% |
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The maximum sensible cooling capacity of a heat pum should be within ________% of the calculated sensible heat gain of a structure with a large heating load. |
+25% |
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The combined output of a heat pump and its auxiliary heat should not exceed the calculated heat loss of a home by more than ________% |
15% |
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What amount of auxiliary electric heat needed when the output of a heat pump on a design day equals 18,800 Btuh and the heat loss of a home is 29,700 Btuh? |
(Heat loss - Heat pump output)/3,413 (29,700 - 18,800)/3,413 = 3.2kWh |
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The three processes that transfer heat energy are conduction, convection, and ________. |
Radiation |
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Heat transfer that occurs when substances of different temperatures are in contact with each other is called ________. |
Conduction |
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What effect does raising the pressure in a sealed system have on refrigerant? |
The refrigerant's boiling point increases |
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What is the primary danger to people near an accidental refrigerant release or spill? |
Suffocation caused by the heavier refrigerant displacing oxygen in the air |
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The maximum temperature at which refrigerant may be stored is ________ degrees F when the container is no more than ________% full of liquid by volume. |
125 F, 80% |
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Boiling of the refrigerant occurs in which system component? |
Evaporator |
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Why is superheat necessary in a system that utilizes hermetic compressors? |
It ensures that dry vapor reaches the compressor so that mechanical damage does not occur |
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When the heat load on an evaporator increases, what is the effect on the system? |
Suction pressure and discharge pressure both increase |
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What type of energy is transferred when work is done in the condenser? |
Both latent and sensible heat energy |
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What is the primary function performed by a thermal expansion valve? |
It maintains the correct superheat in the suction vapor leaving the evaporator |
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Which component pumps refrigerant through the system and raises the vapor temperature? |
Compressor |
