Why are standard low-efficiency furnaces no longer manufactured?
A) The standing pilot flame safety devices were deemed too hazardous after several technicians were electrocuted while changing a thermocouple.
B) Thermocouples proved to be an unreliable technology.
C) They cannot provide the minimum 80 percent AFUE required by DOT.
D) The thermocouple flame safety devices they use have not been thoroughly field tested.
C
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When drawing a PH diagram of an operating system, how is placement of the metering device line determined?
A) The metering device line starts where the condenser line crosses the temperature of the liquid line and then drops straight down until it crosses the evaporator line. B) The metering device line starts where the compressor line crosses the temperature of the liquid line and then drops straight down until it crosses the condenser line. C) The metering device line starts where the condenser line crosses the temperature of the liquid line and then goes straight across until it crosses the compressor line. D) The metering device line starts where the condenser line crosses the temperature of the liquid line and then drops straight down until it crosses the compressor line.
One of the primary features of the smart grid concept is _____
A) the guarantee that power will never be interrupted B) the elimination of fossil fuel-based power C) two-way communication between loads and power sources D) power that costs the same for all customers, at all times of the day
_________ equipment means listing measurments as well as the number and kinds of equipment needed for the job.
Fill in the blank(s) with the appropriate word(s).
The electrical switching in an electronic thermostat is often done by:
A) Resistors. B) A mercury bulb. C) Batteries. D) Small relays.