CSLB C20 FINAL EXAM 2026 ACTUAL QUESTIONS AND
ANSWERS GRADED A+
✔✔What is the minimum clearance from the ground for a metal duct?
4"
6"
8"
12" - ✔✔4"
✔✔What is the maximum length for a 240 V power cord on a window-mounted room air
conditioner?
3 ft
6 ft
8 ft
12 ft - ✔✔6 ft
✔✔Duct vibration isolators should not exceed _____ in length. - ✔✔10 in
✔✔A controlling device for regulating the flow of volatile refrigerant into a cooling unit,
actuated by changes in evaporative pressure and superheat of the refrigerant leaving
the cooling unit, is known as a:
thermostatic expansion valve
constant pressure valve
direct-acting diaphragm valve
discharge valve - ✔✔thermostatic expansion valve
✔✔Type-B vents are recommended for:
incinerators
combination gas-oil appliances
appliances convertible to solid fuel
standard gas-fired furnaces - ✔✔standard gas-fired furnaces
✔✔What part of a gas furnace is not essential?
pilot light
pressure control
limit control
all of the above - ✔✔pressure control
✔✔The most common duct-sizing procedure is:
, velocity reduction
equal friction
static regain
COP - ✔✔equal friction
✔✔In a typical split central air-conditioning system, the warm-air unit is located:
in the attic
outside the house
in the house
inside the condensing unit - ✔✔in the house
✔✔Where do you locate the furnace in a gravity warm-air heating system?
north
next to the basement wall that faces south
west and in the highest part of the house
in the lower part of the house and as near to the center as possible - ✔✔in the lower
part of the house and as near to the center as possible
✔✔What is dangerous about LP gas?
it attacks the nervous system
it has no taste or color
it accumulates near the ceiling and can ignite
it accumulates at floor level and can explode - ✔✔it accumulates at floor level and can
explode
✔✔Why is a warm-air register placed under a window?
so it is out of the way
it will heat the air faster
drafts are eliminated
decoration - ✔✔drafts are eliminated
✔✔Cranes with a boom longer than 60 ft or with a rating greater than _____ require a
boom-angle indicator. - ✔✔15 tons
✔✔Type A vents are suitable for:
venting gas appliances and oil-burning equipment
venting gas appliances in attic installations
venting gas-fired boilers that produce temperatures at the draft diverter not in excess of
550°F
ANSWERS GRADED A+
✔✔What is the minimum clearance from the ground for a metal duct?
4"
6"
8"
12" - ✔✔4"
✔✔What is the maximum length for a 240 V power cord on a window-mounted room air
conditioner?
3 ft
6 ft
8 ft
12 ft - ✔✔6 ft
✔✔Duct vibration isolators should not exceed _____ in length. - ✔✔10 in
✔✔A controlling device for regulating the flow of volatile refrigerant into a cooling unit,
actuated by changes in evaporative pressure and superheat of the refrigerant leaving
the cooling unit, is known as a:
thermostatic expansion valve
constant pressure valve
direct-acting diaphragm valve
discharge valve - ✔✔thermostatic expansion valve
✔✔Type-B vents are recommended for:
incinerators
combination gas-oil appliances
appliances convertible to solid fuel
standard gas-fired furnaces - ✔✔standard gas-fired furnaces
✔✔What part of a gas furnace is not essential?
pilot light
pressure control
limit control
all of the above - ✔✔pressure control
✔✔The most common duct-sizing procedure is:
, velocity reduction
equal friction
static regain
COP - ✔✔equal friction
✔✔In a typical split central air-conditioning system, the warm-air unit is located:
in the attic
outside the house
in the house
inside the condensing unit - ✔✔in the house
✔✔Where do you locate the furnace in a gravity warm-air heating system?
north
next to the basement wall that faces south
west and in the highest part of the house
in the lower part of the house and as near to the center as possible - ✔✔in the lower
part of the house and as near to the center as possible
✔✔What is dangerous about LP gas?
it attacks the nervous system
it has no taste or color
it accumulates near the ceiling and can ignite
it accumulates at floor level and can explode - ✔✔it accumulates at floor level and can
explode
✔✔Why is a warm-air register placed under a window?
so it is out of the way
it will heat the air faster
drafts are eliminated
decoration - ✔✔drafts are eliminated
✔✔Cranes with a boom longer than 60 ft or with a rating greater than _____ require a
boom-angle indicator. - ✔✔15 tons
✔✔Type A vents are suitable for:
venting gas appliances and oil-burning equipment
venting gas appliances in attic installations
venting gas-fired boilers that produce temperatures at the draft diverter not in excess of
550°F
