HVAC Random 25-01

Heat of fusion of water, is the heat released from a substance to change irt from a liquid state to a solid state. The heat of fusion of ice is ___ Btu per pound.

• 144
• 109
• 42
• 31

Select one of the most common result produced by a small difference in a system.

• short cycling
• temperatures that are too low
• long off periods
• an iced coil

Avoid contact with contaminated lubricant from a hermetic system that is dirty and smells bad because it may be

• acidic
• explosive
• phosgenic
• radioactive

In many condensing unit applications, it is necessary to heat the compressor to evaporate liquid refrigerant trapped in the oil. Most large compressors for commercial applications are manufactured and equipped to handle this situation using a ___.

• crankcase heater
• low temperature heating circuit
• high temperature cooling circuit
• off cycle oil pressure reducer

What does a sling psychrometer measure directly?

• temperature and dew point
• heat and cold
• gain and drops
• wet bulb and dry bulb

Materials within plenums shall be noncombustible or shall have a smoke-developed index of NOT MORE THAN ____ when tested in accordance with ASTME E 84.

• 450
• 250
• 50
• 25

Which component may be added to a refrigeration system to prvent moisture from entering the compressor?

• receiver
• accumulator
• liquid line filter drier
• crankcase pressure regulator

If a vessel of AT LEAST ____ deep with an open top is labeled a confined space.

• 8 feet
• 6 feet
• 4 feet
• 2 feet

What is the applied voltage across an electric heater with a total current draw of 22 amperes and a resistance of 11 ohms?

• 230
• 240
• 242
• 248

Mechanical joints, in a refrigeration system, shall not be used on annealed temper copper tube in sizes larger than ___ OD size.

• 7/8 inch OD
• 1 1/8 inches OD
• 5/8 inch OD
• 3/4 inch OD