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HVAC-R Midterm EXAM with complete solution 2024_2025
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HVAC-R Midterm EXAM with complete solution 2024_2025
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HVAC-R Midterm EXAM with completesolution 2024/2025
1.) Temperature can be defined as? - ANSWER-Level of heat
2.) Sensible heat causes? - ANSWER-Rise in temp.
3.) What direction does heat flow? - ANSWER-Warm to cold
4.) Four types of temperature scales? - ANSWER-Fahrenheit,Rankine,Celsius, &
Kelvin
5.) 1 BTU will raise 1lb. of water? - ANSWER-1 Degree
6.) Latent heat causes? - ANSWER-Change of state
7.) Pressure in a bourdon tube, what happens to gauges? - ANSWER-Causes
them to straighten
8.) How is heat transferred by convection? - ANSWER-Moving a medium such as
air, or water
9.) If evaporator is 76 psi & compressor inlet is 65 degree Fahrenheit, what's the
superheat? - ANSWER-Convert 76 psi to temp. & subtract it fromthe inlet temp. of
65 degree fahrenheit (R-22 @ 76 psi=45 degree) 65 - 45 = 20degree superheat
10.) 1 ton capacity of refrigeration will remove? - ANSWER-12,000 btu's in 1 hr
11.) What's the function of the evaporator? - ANSWER-Absorbs heat
12.) What's the compressor doing refrigeration? - ANSWER-Moves refrigerant
from low to high side
, 13.) Ice melts in an ice box, why? - ANSWER-When it absorbs heat from the door
opening & food placed inside
14.) What color can is R-12? - ANSWER-White
15.) What color can is R-22? - ANSWER-Green
16.) What's sub cooled liquid? - ANSWER-Temp. Drop after 100% condensing
17.) Where does the heat in a condensor go on an air cooled unit? - ANSWER-Air
18.) Where does the heat in a condenser go on a water cooled unit - ANSWER-
Water
19.) How to get sub cooling temp? - ANSWER-condensing pressure is 260 psi,
liquid line temp is 100 degree Fahrenheit (R-22), convert 260 psi to temp = 120
degree Fahrenheit - 100 degree Fahrenheit from liquid line = 20 degree Fahrenheit
(R-22)
20.) What's a metering device do? - ANSWER-Meters refrigerant
21.) Why are ACR lines insulated? - ANSWER-Condensation
22.) What's the grade of ACR tubing? - ANSWER-L ( Capped & Dry)
23.) 3 types of thermometers? - ANSWER-Glass, Digital, and Pocket dial Indicator
24.) What side of the system should be insulated? - ANSWER-Low pressure
side/Suction side
25.) What lengths does soft copper tubing come in? - ANSWER-25' & 50' ft. rolls
26.) What is a air acetylene torch used for? - ANSWER-Brazing
27.) Size 1/2 inch would refer to what in plumbing? - ANSWER-ID (Inside
Diameter)
28.) Pluming copper tubing is measured by? - ANSWER-ID (Inside Diameter)
29.) Refrigeration copper tubing is measured by? - ANSWER-OD (Outside
Diameter)
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