Heat Pump Flashcards
(29 cards)
Which of the following factors affect a customers comfort? A)air movement B)humidity C)temperature D)all of the above
All of the above
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 pump 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 is 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?
3.2kwh
The 3 processes the 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 and accidental refrigerant release or spill?
Suffocation calls by the heavier refrigerant displacing oxygen in the air.
The maximum temperature at which refrigerant may be stored is _________Fahrenheit when the container is no more than __________%full of liquid by volume.
125°, 80%
Boiling of the refrigerant occurs in which system component.
Evaporator
Why is super heat 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
How are hermetic compressors motors cooled
With suction vapor drawn from the evaporator.
Heat pump compressors sometimes run hotter then compressors used in cooling‐ only units because heat pumps compressors _______.
Exhibit low refrigerant density at low suction pressures during the heating cycle
When is crankcase heat most needed.
When the compressor is off
Work done on the refrigerate in the condenser is transferred as______.
Both sensible and latent heat
Why are more circuits needed in the outdoor coils used in heat pumps than in the condenser coil used in the cooling only units?
To keep the pressure drop across the outdoor coil low
What is the typical water flow rate per ton of cooling for a water source heat pumps operating in closed loop systems?
3 gpm
What tool should be used to shorten a capillary tube
A triangular or knife edge file
Which pressure in A TEV is the operating pressure
Bulb pressure
