Electric Motors
A motor's speed is determined by ____.
Number of poles.
Refrigeration can be described as
the process of removing heat from a place where it is not wanted to a place where it makes little or no difference
What is the name of a compressor with a piston?
Reciprocating
What is super heat?
The difference between the saturation temperature of the evaporator and the suction line temperature.
What is the vent called for a furnace?
Flue Pipe
Start windings are placed ____ with the run windings.
slightly out of phase
What happens when room temperature soda is poured into a glass of ice?
The ice melts because it is absorbing heat from the soda.
Compressor that compresses the gas between two scrolls is a ?
Scroll compressor
What is subcooling?
The temperature difference between the condensing coil and the liquid line temperature.
What is Flame rectification?
Voltage traveling across the flame and back to board through the ground.
A permanent split capacitor (PSC) motor that is running and up to speed will have the start winding
energized
What is the role of the metering device?
The lower the pressure/temp of the liquid refrigerant.
What happens when liquid refrigerant gets into the compressor?
The liquid will mix with the oil and either foam up when the compressor starts or it could carry the oil out of the compressor.
What tool do you use to measure airflow?
anemometer
Name two types of Gas valves.
Good Job
A current magnetic relay opens and closes its contacts based on the ____.
the current of the run winding
Name all four parts of the refrigeration cycle
Compressor
Meter
Evaporator
Condenser
When a refrigerant enters the compressor, it is a ____ and when it leaves the compressor, it is a ____.
low pressure low temperature superheated vapor, high pressure high temperature superheated vapor
Explain what Delta T is?
the difference between the temperature of the air entering an HVAC unit (supply air temperature) and the temperature of the air leaving the unit (return air temperature)
Name two types of ignitors
Good Job
T or F
A Capacitor Start Capacitor Run (CSCR) motor that is wired with a potential relay will have the start winding energized when the relay's contacts open.
True
How does the refrigerant leave the compressor?
High pressure high temp vapor
Describe how to find the compressor ratio.
The compression ratio is the ratio of the absolute discharge pressure (psia) to absolute suction pressure (psia), found using the formula Discharge Pressure Absolute รท Suction Pressure Absolute.
How many cfms are in a ton?
400
What if the steps to a furnace lighting?
W signal, Draft inducer, Pressure switch, ignitor, Gas valve, flame sensor.