Refrigeration Basics
Environmental Protection Agency
Where is low pressure super heated vapor found on the refrigeration cycle
in the suction line going to the compressor
a Tool used to measure volts, ohms, and amperages along with more measurements
High head pressure, High amp draws, and possible compressor overheating on overload.
What does an EPA 608 Universal Certificate Cover in terms of applications?
Small appliances, Low, medium, and high temp applications.
What are all the things a condenser does?
Rejects heat, de-super heats, condenses (change of state from vapor to liquid), and Sub cools.
The relationship between Volts, Ohms, and Amperes. E= Voltage (Electromotive Force, I= Amperage (intensity), and R= Resistance (ohms)
What does a compressor do and what is it?
Moves Refrigerant throughout the system, Increases a low temperature superheated vapor to a high pressure super heated vapor, Heart of the system and it's a vapor pump.
What would be an Indication or a way of checking Valves in a compressor?
By doing a bench test and front seating the suction line service valve, then manually running compressor until t pulls in a vacuum. wait several minutes to ensure pressure does not rise if it does this is due to bad reed valves in the compressor.
what is passive recovery?
passive recovery is relying on the pressure of the system to push the refrigerant out into a non pressurized container (A BAG!)
How do you calculate the Compression Ratio of a system?
add atmospheric pressure to both low and high sides pressures of the system (+14.7 psi) the divide the high side b the low side absolute pressure.
what is the wattage of a unit pulling 40 amps at 240V?
What is the btu?
9,600 watts
32,755 btus
What device absorbs heat from the conditioned space?
Evaporator
What would high super heat and low subcooling most likely be attributed to?
Low Charge
what is the leak rate for comfort cooling, commercial refrigeration and Industrial process refrigeration?
Comfort cooling = 10%
Commercial refrigeration = 20%
Industrial Process Refrigeration = 30%
What is the formula for subcooling?
High side saturation temperature - Liquid line temperature
What are the two types of External relays used in commercial refrigeration?
Current relay and Potential relay
on a Defrost clock what connection is for defrost termination? what terminals control Freeze? and what terminals control Defrost?
Defrost termination = X
Freeze = 2-4
defrost = 1-3
What would high super heat and High subcooling be an indication of?
a Restriction
Why is and HFO called a hydrofluoroolefin?
the double bond that holds the molecule together is called an olefin bond.