On a commercial refrigeration system with electric defrost, what does the compressor do during the defrost cycle?
A) It operates to provide the heat for defrost.
B) It runs backwards to pump hot gas into the evaporator.
C) It cycles like it normally would.
D) It shuts off.
D
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The bricks used in brick-faced concrete curtain wall panels are generally
A) thinner than those used in brick veneer construction. B) thicker than those used in brick veneer construction. C) of the same thickness as those used in brick veneer construction. D) any one of the above, depending on the building.
An electrical conductor is an element with ________ electrons in its outer orbit
A) Exactly 4 B) Less than 4 C) Less than 2 D) More than 4
Gasoline should be stored in approved containers that include what color(s)?
A) A red container B) A red container with yellow lettering C) A yellow container D) A yellow container with red lettering
What advantage is there to maintaining a negative pressure on the heat exchanger?
A) The negative pressure helps draw in return air from the house, increasing efficiency. B) Combustion air can only be drawn into the oil burner if a negative pressure is maintained. C) The vent will not work unless the heat exchanger is at a negative pressure. D) Safety; it ensures combustion products do not leak out into the air stream.