Troubleshooting
target temperature difference between supply and return
16-20 degrees
Fins on a coil increase
Surface area and heat transfer
Primary purpose of a metering device
Creates pressure drop
Pressure that is less than the surrounding pressure
Vacuum
The air temperature readings you need to know before assessing refrigerant pressures
Ambient temperature and return air wet bulb
Whats the main cause of a system to freeze up
Low airflow
If air velocity is too high across an evaporator it can decrease
dehumidification
What increases the pressure in a system
Compressor
Target goal when evacuating a system
500 microns
Readings needed to measure Suciton line superheat
suction line pressure and temperature
The coldest the liquid line can get
Is the temperature of the air or water it is rejecting heat to
The bent pieces of copper at the end of a coil
u-bends
Stores Excess liquid refrigerant and helps ensure only liquid is leaving condenser
How do you get all of the moisture out of poe oil
Desiccants in a filter drier
the three pressure of air in a duct
Static, Velocity, and total pressure
Moisture in a refrigeration system causes
Acidity and compressor failure
the two main types of air coils are
microchannel and tube and fin
Installed on discharge line and absorbs noise and vibration
muffler
Methods to get more moisure and refrigerant out of oil during evauation.
Heat oil up, shake it, blast nitrogen through it (triple evac).
The two readings you need to determine compression ratio
Discharge and suction pressure
High superheat and low subcooling is a common sign of this
Undercharge
The temperature at the midpoint of the coil should be
Saturation temperature of the refrigerant
This can be installed in the suction after a burnout to absord acidity
Suction line drier
What should you open when first starting your vacuum (especially if a lot of moisture is present) until about 1500-3000 microns.
Gas ballast
Readings needed to determine unit airflow using fan performance chart
Return and supply static pressure (ESP)