Sheet Metal and HVAC Flashcards
6 cards from real Other Skilled Trades practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Sheet Metal and HVAC flashcards as text
What certification is required by federal law for HVAC technicians who handle refrigerants?
Answer: EPA Section 608 Certification
EPA Section 608 Certification is required by federal law for any technician who purchases or handles refrigerants to prevent illegal venting that harms the ozone layer.
What does the MERV rating system measure for HVAC filters?
Answer: Minimum Efficiency Reporting Value — how effectively the filter captures particles
MERV (Minimum Efficiency Reporting Value) rates how effectively an air filter captures particles from 0.3 to 10 microns — higher MERV numbers indicate better filtration.
In an air distribution system, what is the difference between a supply air register and a return air grille?
Answer: Supply registers deliver conditioned air into the space; return grilles draw room air back to the air handler
Supply registers blow conditioned air from the air handler into the room, while return grilles pull room air back to the air handler to be reconditioned.
What is the purpose of a heat exchanger in a gas furnace?
Answer: To transfer heat from combustion gases to supply air without mixing the two airstreams
The heat exchanger separates the combustion gases (which contain CO and other pollutants) from the supply air while transferring heat through the metal wall between them.
What does 'subcooling' mean in the context of HVAC refrigeration systems?
Answer: Liquid refrigerant is cooled below its condensing temperature in the liquid line
Subcooling is the number of degrees the liquid refrigerant in the liquid line is cooled below its saturated condensing temperature, ensuring no flash gas enters the expansion device.
What type of duct fitting reduces turbulence and pressure loss when making a 90° turn in a rectangular duct system?
Answer: Square throat elbow with turning vanes
Square throat elbows fitted with turning vanes redirect airflow smoothly through the 90° turn, significantly reducing turbulence and static pressure loss compared to unvaned elbows.