Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
Which of the following factors affects a customer's level of comfort? |
Temperature, humidity, air movement, air cleanliness, fresh air ventilation |
|
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% |
|
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% |
|
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% |
|
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 |
|
The three processes that transfer heat energy are conduction, convection, and ________. |
Radiation |
|
Heat transfer that occurs when substances of different temperatures are in contact with each other is called ________. |
Conduction |
|
What effect does raising the pressure in a sealed system have on refrigerant? |
The refrigerant's boiling point increases |
|
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 |
|
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% |
|
Boiling of the refrigerant occurs in which system component? |
Evaporator |
|
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 |
|
When the heat load on an evaporator increases, what is the effect on the system? |
Suction pressure and discharge pressure both increase |
|
What type of energy is transferred when work is done in the condenser? |
Both latent and sensible heat energy |
|
What is the primary function performed by a thermal expansion valve? |
It maintains the correct superheat in the suction vapor leaving the evaporator |
|
Which component pumps refrigerant through the system and raises the vapor temperature? |
Compressor |