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HVAC MIDTERM EXAM with complete solution 2024_2025.
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HVAC MIDTERM EXAM with complete solution 2024_2025.
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HVAC MIDTERM EXAM with completesolution 2024/2025
One watt (1 W) of electrical energy is equivalent to ________ Btu's of heat energy.
- ANSWER-3.413 Btus
Latent heat is also known as.
A. Heat quantity
B. Heat Intensity
C. Hidden Heat
D. Specific Heat - ANSWER-C. Hidden Heat
What is superheat?
A. A vapor with a temperature above its saturation temperature.
B. The temperature of refrigerant leaving the evaporator
C. The temperature of refrigerant entering the compressor.
D. None of the above - ANSWER-A. A vapor with a temperature above its
saturation temperature.
The indoor coil of a heat pump system serves as the _____ during the cooling
season, and as the _____ during the heating season. - ANSWER-evaporator,
condenser
In which component of a refrigeration system is heat removed? - ANSWER-The
Condenser
, What is the most common type of heat pump used in residential applications? -
ANSWER-Air-to-air split system
What indoor air volume (expressed in cfm) would be required for a heating unit
that has a 50°F temperature rise and an output of 80,000 Btuh?
* See formula page - ANSWER-1481 cfm
How much auxiliary heat will be required on a design day when a home's heat
loss is 35,600 Btuh and the heat pump output is 17,200 Btuh?
* See formula page - ANSWER-5.39 kW or 5,390 watts
Why does the indoor coil of a heat pump need more area than the indoor coil of a
cooling-only unit? - ANSWER-To prevent the condensing temperatures and
corresponding head pressures from becoming too high during the heating cycle.
Why does a heat pump require three-function control? - ANSWER-Because a heat
pump performs three functions-it provides cooling, it provides heating, and it
must defrost the outdoor coil when ice forms on it.
What is the coefficient of performance (COP) of a heat pump? - ANSWER-A
comparison of how much heat the heat pump is producing compared to how
much heat an electric furnace would produce using the same amount of
electricity.
What three types of compressors are used in residential heat pump applications?
- ANSWER-Reciprocating, scroll, and rotary.
Name two problems that occur when flash gas enters a TEV while a system is
operating? - ANSWER-The valve operates inefficiently, the system
loses capacity, and superheat increases.
Typical superheat values measured at the evaporator outlet of a properly
operating heat pump system is about how many degrees? - ANSWER-10 to 12
degrees
((Ref: 124/2))
TEVs that limit the pressure created by an expanding bulb charge are called
what? - ANSWER-Maximum operating pressure (MOP)
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