PSI
The adding of heat to a refrigerant that has reached its vapor saturation point is referred to as what?
Superheat
The specific heat of air is what?
0.24Btu/lb
Define the term "Enthalpy"
The measure of the heat content of a substance.
Which of the following is permitted to be used to pressure check a refrigeration system?
Nitrogen
Using Ohm's law, what would "R" equal if E=120 and I=40
3
A circuit having a voltage of 120 volts applied and is drawing 10 amps would have a resistance of how many ohms?
12 ohms
A positive temperature coefficient (PTC) device is used for which of the following purposes?
start assist for PSC motor.
A 24-volt transformer with a rating of 60-VA has maximum current carrying output of how many amps?
2.5A
What is rectifier used for?
Change AC voltage to DC voltage
A thermistor may be used for which of the following?
To provide temperature readout, to assist in the starting of a PSC motor, and to stop a motor on an overload condition.
Which of the following is TRUE about an internal motor temperature cutout?
opens the circuit on a temperature rise and stops the motor.
Which of the following is adjustable on a thermostat?
The bimetal strip
Which of the following is a cause of hermetic compressor motor overheating and cutting out on the internal overload device?
Refrigerant undercharge
The point or pressure setting at which a pressure sensing device interrupts the electrical circuit is knows as the what?
cut-out
Which of the following is NOT a type of a fan switch used on a a gas furnace?
temperature on - time off
Which of the following is required when a thermostat sub-base designed for two 24 volt power sources is used with one power source?
A jump wire is required to be connected between RH and RC terminals?
Which of the following is FALSE about the uses of direct digital controls
It is a manual controlled system that requires more maintenance
The number of poles in a single phase motor determines the what?
RPM
An open circuited run capacitor has which of the following effects on a motor?
Running amperage will be high, motor will get hot if operation is at full load.
To provide proper oil return to the compressor the suction line must be pitched toward what?
The compressor
A Btu is what?
The amount of heat required to raise 1lb of water 1 degree Fahrenheit
The purpose of a fan control is to what?
start and stop fan motor
Which of the following is used in a permanent split-capacitor motor?
Run capacitor
Which of the following motors has the lowest starting torque?
Permanent-split capacitor
A room thermostat should be mounted how far off the floor?
5 feet