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HBA Service Excellence Bootcamp > Refrigeration > Flashcards

Refrigeration Flashcards

Understanding Refrigeration

1
Q

Which section of piping is “A” in the image below reffered to as?

A

Discharge line

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2
Q

Which section of piping is “B” in the image below reffered to as?

A

Liquid line

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3
Q

Which section of piping is “C” in the image below referred to as?

A

Suction line

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4
Q

What state is the refrigerant in the condensor coil?

A

Saturated

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5
Q

What state is the refrigerant in the evaporator coil?

A

Saturated

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6
Q

What state ideally is the refrigerant at “A” in the image below?

A

Vapour

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7
Q

What state ideally is the refrigerant at “B” in the image below?

A

Liquid

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8
Q

What state ideally is the refrigerant at “C” in the image below?

A

Vapour

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9
Q

What is the maximum temperature drop you can have across a filter drier?

A

3°f

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10
Q

What is the purpose of an accumulator?

A

To prevent liquid refrigerant from entering the compressor.

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11
Q

What is the ideal amount of superheat in a system?

A

10°f of superheat

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12
Q

What is the ideal amount of subcooling in a system?

A

10°f of subcooling

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13
Q

What is the ideal SST (Saturated suction temperature)

A

35°f - 45°f

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14
Q

How do you calculate subcooling?

A

SCT - Liquid line temperature

For example
SCT - 95°f
Liquid line temperature - 85°f
Subcooling: 95 - 85 = 10

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15
Q

How do you calculate superheat?

A

Suction line temp - SST
For example
SST - 40°f
Suction line temperature - 55°f
Superheat: 55 - 40 = 15

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16
Q

Saturated means …

A

**the boiling point, of a vapour/liquid mixture **

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17
Q

The slower the fan speed the —– the temp drop but the —– you will boil the refrigerant.
higher/lower
more/less

A

higher the temp drop but the less you will boil the refrigerant

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18
Q

How do we know we have %100 liquid going to the TXV

A

By having 10°f of subcooling

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19
Q

What is wrong with the system pictured?

A

Fan speed to high.

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20
Q

What is wrong with the system pictured?

A

Fan speed to low.

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21
Q

What is wrong with the system pictured?

A

Nothing.

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22
Q

What is wrong with the system pictured?

A

It is low on charge

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23
Q

What is wrong with the system pictured?

A

There is no load.

24
Q

What is wrong with the system pictured?

A

The system is overcharged.

25
Q

What is wrong with the system pictured?

A

Fan speed to high.

26
Q

What is wrong with the system pictured?

A

Airflow is low.

27
Q

What is wrong with the system pictured?

A

High load on the system.

28
Q

What is wrong with the system pictured?

A

Low charge.

29
Q

What is wrong with the system pictured?

A

Bad Metering Device.

30
Q

What is wrong with the system pictured?

A

Overcharged.

31
Q

What is wrong with the system pictured?

A

Restriction.

32
Q

What is wrong with the system pictured?

A

Metering device is stuck because refrigerant was added and SST didnt change.

33
Q

What is wrong with the system pictured?

A

Fan speed set to high.

34
Q

What is wrong with the system pictured?

A

Fan speed set to low.

35
Q

What is wrong with the system pictured?

A

High load.

36
Q

What is wrong with the system pictured?

A

Overcharged.

37
Q

What is wrong with the system pictured?

A

Restriction

38
Q

What is wrong with the system pictured?

A

Empty.

39
Q

You add refrigerant to this system but your SST does not move. What is your next step?

A

Pump down test to see if the TX valve isn’t working.

40
Q

What is wrong with the system? What do you need to do?

You arrive to find the coil is frozen over. You check history and you find that the evap and blower/hx were cleaned 12 months ago. Filter is clean, all registers are open, including return. The ECM is speeding up to attempt to move correct CFM through the frozen coil, you ensure it is set to 400 CFM per ton.

A

Either the customer changed the filter before you got there or the ECM motor has 1 speed getting stuck.

41
Q

In a residential A/C, the optimal range for saturated suction temperature is 30°F-40°F when considering due point.
True/False

A

False
Optimal SST is 35°F - 45°F

42
Q

What is the name of the gas created when refrigerant is burned?

A

phosgene gas

43
Q

What are the 4 types of metering devices in residential AC?

A

1. Piston
2. Thermostatic expansion valve
3. Electronic expansion valve
4. Capillary

44
Q

How do you charge a system with a piston metering device?

A

Superheat

45
Q

How do you charge a system with a TXV metering device?

A

Subcooling

46
Q

How do you charge a system with an EEV metering device?

A

Weighing it in or by subcooling on the max speed

47
Q

How do you charge a system with a capillary as a metering device?

A

Superheat

48
Q

What is the function of a TXV?

A

Maintains a fully saturated evaporator coil without damaging the compressor?

49
Q

During the winter what is the purpose of the condenser fan motor in a heat pump?

A

To maintain pressures and temperatures across the heat exchanger

50
Q

If a compressor is recieving high super heat the system can become compromised and run the risk of creating what?

A

Toxic acidic refrigerant & oil

51
Q

Which one of the following might you see in a system if there is no TXV?
Check - Flow piston
Back - Check piston
Slam - Check piston

A

Check - flow piston

52
Q

How much quieter is a side discharge heat pump vs a traditional heat pump?

A

36% quieter

53
Q

An air restriction will cause the following readings: Normal subcooling normal head pressure - low superheat low pressure
True/False

A

True

54
Q

3 tonnes of refrigeration is equal to?
A. 200 BTU/min
B. 400 BTU/min
C. 600 BTU/min
D. 800 BTU/min

A

C. 600 BTU/Min

55
Q

With regards to a TX valve, if the sensing bulb loses its charge, the valve will be?
A. There is no sensing bulb on a TX
B. Open
C. Closed
D. Mid position

A

C. Closed

56
Q

An externally equalized TX valve senses evaporator ___?
A. Outlet Pressure
B. Inlet Pressure
C. Head Pressure
D. Saturation Temperature

A

A Outlet Pressure

HBA Service Excellence Bootcamp (7 decks)

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