Test your basic knowledge |

Residential Air Conditioning

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. If pressure rises - what happens to the superheat?
30 degrees F
Pi x radius squared
Shorted winding - open winding - and grounded winding
It rises

2. Why is it necessary to have multiple refrigerant circuits in some evaporator coils?
To lower the amount of pressure drop through the coil
To keep refrigerant from absorbing heat and to prevent condensation from forming on the line
6
Average feet per minute X area in square feet (H' x W'/144)

3. 8' round duct has a ballpark cfm of what?
Any amount
With a minimum of three evenly spaced self-tapping screws
200
Pi x radius squared

4. How many cfm per ton?
In parallel
A band 4 inches or more in width
It will have a decrease in superheat
400

5. Why is it necessary to have multiple refrigerant circuits in some evaporator coils?
To lower the amount of pressure drop through the coil
30-35 degrees above ambient
Suction
Stranded

6. What type of air conditioning system must be charged using the superheat method?
A piston type metering device
Over 800 degrees F
In parallel
To remove humidity and lower dry bulb temperature

7. Do you need a vent on a push-through evaporator?
Common
1/4'
Yes
200

8. What is the normal evaporator temperature?
Subtract ambient temperature from 100
45 degrees F
The takeoff fitting
Over/under and side by side

9. How many amps can 10 g wire handle?
Rise
30 A
15% silphos
SEER includes the energy used in the start-up and shut-down cycles

10. What sort of pressure will a push-through evaporator have?
It will be low
20 degrees above ambient
To keep refrigerant from absorbing heat and to prevent condensation from forming on the line
Positive

11. How do you calculate EER?
Vapor
No
Btu/hr (output) / wattage (input)
45-55%

12. Which type of wire can handle a higher ampacity?
Stranded
It will be low
ACR (air-conditioning refrigeration) tubing
TXV

13. What is a package unit?
Heat load
Belt drive and direct drive
Duct - electrical - and mechanical
An air-conditioning system that has all four components (compressor - condenser - metering device - and evaporator) in one housing.

14. What are the four materials used to make duct?
Fiberglass
Sheet metal - galvanized sheet metal - fiberglass - and flexduct
A band 4 inches or more in width
A bypass duct or a dump zone

15. How much superheat do you need to prevent liquid refrigerant from entering the compressor?
Yes
To keep refrigerant from absorbing heat and to prevent condensation from forming on the line
Any amount
To remove humidity and lower dry bulb temperature

16. If the suction pressure rises - what happens to the head pressure?
False
By increasing the surface of the condenser coil
Yes
It also rises

17. What gauge is thermostat wire?
Nitrogen with a small amount of refrigerant
18 gauge
It will be high
Before the vent

18. Superheat should never be below how many degrees
In parallel
Side-by-side and over-and-under
5 degrees
No

19. If the rpm's are 1050 - how many poles does the motor have?
8
The suction line or the low-pressure side
Yes
6

20. What do you use to connect square and rectangular ductboard together?
Blended refrigerants
To remove humidity and lower dry bulb temperature
S-clips and drives (cleats)
40 degrees F

21. How are the high pressure switch and the low pressure switch wired with the compressor contactor?
Static pressure - velocity pressure - and total pressure
In series
20 degrees above ambient
It will have a decrease in superheat

22. What are the two types of blower drives?
Belt drive and direct drive
40 degrees F
Individual return air systems and central return air systems
ACR (air-conditioning refrigeration) tubing

23. Where do you apply flux when soldering?
Outside of the male fitting
2 minutes
Vapor
L-type

24. How many BTU's per ton?
On the common terminal
Shorted winding - open winding - and grounded winding
12000
45-55%

25. What is used to measure static air pressure in ducts.
It rises
Inclined manometer
Pull a vacuum
100 psig

26. The fan switch opens at what temperature?
105 degrees F
Negative
A band 4 inches or more in width
40 degrees F

27. The furnace size is calculated by what?
20 degrees above ambient
200
30-35 degrees above ambient
Heat loss

28. What are normal conditions - as defined by the ARI.
It also rises
95 degrees F outside - 80 degrees F inside - and 50% relative humidity
Average feet per minute X area in square feet (H' x W'/144)
When it is a pull-through evaporator

29. What do you use to connect square and rectangular ductboard together?
By increasing the surface of the condenser coil
Btu/hr (output) / wattage (input)
S-clips and drives (cleats)
Over 800 degrees F

30. What is it called when liquid refrigerant gets into the compressor?
8-12 degrees F
15% silphos
Slugging
A piston type metering device

31. The refrigerant within the evaporator will typically boil at what temperature when it is 75 degrees inside with a relative humidity of 50%?
Subtract ambient temperature from 100
No
100 psig
40 degrees F

32. How does ACR copper pipe come?
No
It will be low
True
Dehydrated with caps on each end

33. The compressor is cooled by liquid refrigerant. (True of False)
False
2 minutes
Outside of the male fitting
When it is above a conditioned space

34. How many amps can 14 g wire handle?
200
15 A
It rises
Before the vent

35. Will a dirty condenser cause a rise or fall in pressure?
Compressor
Rise
Compressor
Indoor fan motor - outdoor fan motor - and the compressor

36. What can cause a decrease in suction pressure on an air-conditioning system?
By increasing the surface of the condenser coil
A dirty evaporator
4
L-type

37. How long should you leave a system off once you kill power before restarting it?
A piston type metering device
2 minutes
25-ft or 50-ft
Boil the liquid refrigerant out ot the oil within the crankcase

38. What are the two types of return air systems in residential installations?
They are larger
Outside of the male fitting
400
Individual return air systems and central return air systems

39. What is the name of the fitting where the branch line leaves the duct?
The takeoff fitting
40 degrees F
With an are rating
It will be high

40. What is the typical pressure differance across a TXV?
100 psig
Dehydrated with caps on each end
In parallel
With 4' saddles

41. What is the typical temperature difference between a standard-efficiency condenser and the ambient temperature?
30 degrees F
Compressor
Suction
25-ft or 50-ft

42. At what temperature will soft solder melt?
300
Btu/hr (output) / wattage (input)
Below 800 degrees F
Potential relay and start capacitor

43. What is considered normal operating conditions?
Slugging
75 degrees F dry bulb indoor - 95 degrees F drybulb outdoor - and 50% relative humidity
Inches of water column (in. WC)
Infiltration and ventilation

44. Why are some ACR tubing lines insulated?
400
Suction
Blended refrigerants
To keep refrigerant from absorbing heat and to prevent condensation from forming on the line

45. What percentage silver do you use to braze two dissimilar metals such as steel and copper?
By increasing the surface of the condenser coil
45-55%
Rise
They are physically larger

46. At what temperature will brazing melt?
40 degrees F
False
Boil the liquid refrigerant out ot the oil within the crankcase
Over 800 degrees F

47. What are the three pressures created by moving air in ductwork?
It will be high
Pi x radius squared
An air-conditioning system that has all four components (compressor - condenser - metering device - and evaporator) in one housing.
Static pressure - velocity pressure - and total pressure

48. What kind of refrigeratnts must be added in liquid form?
75 degrees F dry bulb indoor - 95 degrees F drybulb outdoor - and 50% relative humidity
Blended refrigerants
400
Pull a vacuum

49. What are the two basic duct connection configurations for package units supply and return air ducts?
A swaging tool
With a minimum of three evenly spaced self-tapping screws
Over/under and side by side
Dehydrated with caps on each end

50. Where do you install a trap on a drain line?
To lower the amount of pressure drop through the coil
It will have a decrease in superheat
Rise
Before the vent