CSLB C20 UPDATED 2026 EXAM SCRIPT QUESTIONS
AND ANSWERS GRADED A+
✔✔If the asbestos content of a material encountered at a work site exceeds 1%, what
should you do? - ✔✔put up a caution sign and close off the affected area
✔✔On a residential system that uses more than 50 pounds of freon, what is the
maximum annual leakage rate allowed before repairing the leak is mandatory. What is it
for commercial? - ✔✔15%, 35%
✔✔what is the minimum safe landing clearance diameter for a helicopter? - ✔✔200 feet
✔✔what is the max flexible connector you can use for a heating furnace - ✔✔3 feet
✔✔what is the boiling point of R22 at atmospheric pressure? - ✔✔negative 41 degrees
✔✔what is the minimum clearance between an air duct an a rafter - ✔✔1 inch
✔✔why should there be clearance between an air duct and a rafter? - ✔✔fire safety
purposes
✔✔for most refrigerants, is the the boiling point above or below zero degrees
Fahrenheit? - ✔✔below
✔✔ Duct systems should be installed according to ____ Standards - ✔✔SMACNA
✔✔The type of flue pipe used on gas 80% standard furnace venting systems serving
gas fired systems - ✔✔Type B-Vent
✔✔Which type of gauge would you use for very high vacuums? - ✔✔McLeod type
gauge
✔✔How many BTUs are equal to one kilowatt hour - ✔✔3,414 BTU
✔✔When adjusting gas fired furnaces above 2000 feet, the BTU per hour input should
be reduced 4% for each _____ feet above sea level. - ✔✔4% for every 1,000 feet
✔✔How are residential furnace blower motors classified - ✔✔by starting method
✔✔What is the equation for determining heat loss through a material - ✔✔Q = U times
A times TD
✔✔What is the overfire rating on a small draft hood - ✔✔0.02 inches
AND ANSWERS GRADED A+
✔✔If the asbestos content of a material encountered at a work site exceeds 1%, what
should you do? - ✔✔put up a caution sign and close off the affected area
✔✔On a residential system that uses more than 50 pounds of freon, what is the
maximum annual leakage rate allowed before repairing the leak is mandatory. What is it
for commercial? - ✔✔15%, 35%
✔✔what is the minimum safe landing clearance diameter for a helicopter? - ✔✔200 feet
✔✔what is the max flexible connector you can use for a heating furnace - ✔✔3 feet
✔✔what is the boiling point of R22 at atmospheric pressure? - ✔✔negative 41 degrees
✔✔what is the minimum clearance between an air duct an a rafter - ✔✔1 inch
✔✔why should there be clearance between an air duct and a rafter? - ✔✔fire safety
purposes
✔✔for most refrigerants, is the the boiling point above or below zero degrees
Fahrenheit? - ✔✔below
✔✔ Duct systems should be installed according to ____ Standards - ✔✔SMACNA
✔✔The type of flue pipe used on gas 80% standard furnace venting systems serving
gas fired systems - ✔✔Type B-Vent
✔✔Which type of gauge would you use for very high vacuums? - ✔✔McLeod type
gauge
✔✔How many BTUs are equal to one kilowatt hour - ✔✔3,414 BTU
✔✔When adjusting gas fired furnaces above 2000 feet, the BTU per hour input should
be reduced 4% for each _____ feet above sea level. - ✔✔4% for every 1,000 feet
✔✔How are residential furnace blower motors classified - ✔✔by starting method
✔✔What is the equation for determining heat loss through a material - ✔✔Q = U times
A times TD
✔✔What is the overfire rating on a small draft hood - ✔✔0.02 inches
