HVAC SYSTEMS Flashcards
(16 cards)
How do you calculate BTUs from tons of cooling?
BTU = Tons x 12,000
What is the typical SEER requirement for Florida HVAC systems?
SEER 14 or higher (check updated code)
How is refrigerant line length managed?
Charge must be adjusted for line sets over 25 feet
What refrigerant is commonly used in newer systems?
R-410A
What does superheat measure?
The temperature of vapor refrigerant above its boiling point
What does subcooling measure?
The temperature of liquid refrigerant below its condensation point
What is the function of an expansion valve?
Controls refrigerant flow into the evaporator
What does the accumulator do?
Prevents liquid refrigerant from entering the compressor
What is a TXV?
Thermostatic Expansion Valve - regulates refrigerant flow
What is a typical temperature split across an evaporator coil?
18-22°F difference between return and supply air
What is the function of an evaporator coil?
Absorbs heat from indoor air and transfers it to the refrigerant.
What is the purpose of the condenser coil?
Releases absorbed heat into the outdoor air.
What is the function of a compressor?
Increases refrigerant pressure and moves it through the system.
What is the typical range for superheat in a properly charged system?
8-12°F for fixed orifice; manufacturer-specific for TXV systems.
How is airflow measured in ducts?
In cubic feet per minute (CFM).
What is the formula for calculating CFM (airflow)?
CFM = BTU / (1.08 x delta T)
