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Hvac > Hvac Round 1 > Flashcards

Hvac Round 1 Flashcards

Learn about hvac

1
Q

How do you find the TOTAL superheat?

A

Suction line - saturated temp = Total superheat

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2
Q

Where is the liquid line located?

A

It is located on the high side and runs from the condenser coil to the metering device

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3
Q

What are three ways to transfer heat?

A
  1. Conduction
  2. Convection
  3. Radiant heat
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4
Q

What is the suction line?

A

Tubing that carries refrigerant vapor from evaporator coil to compressor.

Ex. The cold tube with the covering and it’s bigger

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5
Q

Where is the discharge line?

A

It is between the compressor and condenser

Ex. The skinny line

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6
Q

What is a metering device purpose?

A

Converts high pressure liquid into a low pressure liquid by drastically reducing the temperature

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7
Q

What does the evaporating coil do?

A

This coil absorbs heat

As the air from the blower fan moves over the coil. The cold refrigerant inside the coil removes heat from the homes air

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8
Q

What is the saturated temperature?

A

Saturated temperature means boiling point.

Located on your Guage

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9
Q

How long should you let the system run before charging up the system?

A

15min

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10
Q

How do you find the TARGET superheat?

A
  1. You need a good wetbulb reading near the biggest return
  2. You need a dry bulb reading near the bottom of outdoor unit in th shade
    Then you enter both reading into the app
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11
Q

If you have a TXV in front of the evaporator coil what method do you use to charge the system?

A

SUB COOLING METHOD

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12
Q

Before you start charging a system the saturated temp on both ends should be what degree?

A

32 degrees

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13
Q

How do you get the wetbulb reading?

A

You get the wetbulb by taking a psychrometer and taking the reading at the biggest return vent

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14
Q

Purpose of a filter drier?

A

Collects moisture, dirt, metal, and other debris to prevent any from entering the metering device.

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15
Q

What is superheat?

And where does it occur?

A

Superheat is when the vapor is heated above it’s boiling point

And it occurs in the evaporator to protect the compressor

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16
Q

What is subcooloing?

And where does it occur?

A

Subcooloing happens when a liquid is cooled below it’s normal boiling point

And it occurs in the condenser to protect the expansion device

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17
Q

What is a pressure switch?

A

A protective device that usually always sits open.

The only time a pressure switch closes is when the induced fan is running. It creates a vacuum and closes

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18
Q

What is a Accumulator?

A

A tank in the suction line that prevents liquid refrigerant from flowing through the suction line and into the compressor.

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19
Q

What are the three main components of a furnace in order and how much voltage does each take?

A
  1. Induced fan motor connected to the pressure switch 120v (line voltage)
  2. Hot Surface igniter 120v (line voltage)
  3. Gas valve 24V (low voltage)
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20
Q

What is the purpose of a transformer?

A

Main purpose is to convert line voltage

Ex 120v to 24v

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21
Q

What is the normal atmosphere pressure?

A

14.7

22
Q

If your system has a piston, fixed office or capillary tube before the evaporator coil, what method should you use for charging up the system?

A

Superheat method

23
Q

Where is the evaporating and condenser coil located?

A
  1. Evaporating coil is in the house

2. Condenser coil located outside the house.

24
Q

What is a line set?

A

Line sets is simply a pair of copper tubes that connects a condenser to an evaporator

The main difference between a split system and package unit

25
Q

What is the purpose of a thermostat?

What do the wires mean?

A

The thermostat is the main control of the action unit and runs off 24V

Red wire - power
Green wire- fan
White wire- heat

26
Q

What is the purpose of a HEAT PUMP indoor coil and where is it located?

A

It warms or cools the air for the conditioned space.

Heat pumps evaporator coil is located at the bottom or middle of furnace

27
Q

What does refrigerant do?

A

Acts like a sponge that is used to soak up and move heat

28
Q

What is a compound Guage?

A

It’s the blue side Guage and can read below and above atmospheric pressure

29
Q

What is flash gas?

A

Instantaneous evaporation of some liquid refrigerant

30
Q

What does LOTO mean?

A

It means lockout or tag out. And it is a safety procedure to make sure dangerous machines are properly shut off and not be able to start up again

31
Q

When using the superheat method to charge up a system, what Guage do you use when charging it checking?

A

Low side or blue guage

32
Q

What does EPA stand for?

A

ENVIRONMENTAL PROTECTION AGENCY

33
Q

When would you use DC and AC voltage?

A
  1. Battery power works off DC voltage

2. inside buildings you come across AC voltage

34
Q

How does heat travel?

A

From hot to cold

35
Q

4 Major parts of refrigeration

A
  1. Compressor
  2. Condensor coil
  3. metering device
  4. evaporator coil
36
Q

What is refrigeration?

A

To remove heat from a space where it is not wanted

37
Q

What is dry bulb?

A

It’s just ambient temperature

38
Q

What is the compressor?

A

The main part of the unit and is the only electric component.
Only gas can travel through a compressor.
It raises the pressure and heat of the vapor as it pumps into the high side

39
Q

What does OSHA stand for?

A

Occupational Safety and health administration

40
Q

When does water begin to boil and freeze?

A

212 boil

32 freeze

41
Q

If the superheat is lower than targeted superheat do you add or recover refrigerant?

A

The system is overcharged and you need to recover refrigerant

42
Q

If the supergeat is HIGHER than targeted superheat do you add or recover refrigerant?

A

Add refrigerant

43
Q

What is a heat pump system?

A

A compression refrigeration system that can reverse the circulating flow of refrigerant in order to add heat or remove heat from a conditioned space.

This is a possible because it has a reversing valve

44
Q

How do you find TOTAL subcooling?

A

Saturated temp - discharge line = Subcooling

45
Q

What is a high limit switch?

A

Is a protective part of a furnace. If the temperature gets to high it will open the circuit cutting off the gas valve.

Check for continuity to see if functioning right.

46
Q

What does a HEAT PUMP outdoor coil do?

A

The refrigerant cool that absorbs or expels heat for the indoor coil

47
Q

Remember that your target superheat is a MOVING number so often should you check?

A

Check every 5-8 mins

48
Q

In a heat pump system, Cooling mode usually means it runs how?

A

Cooling mode: runs like traditional SPLIT SYSTEM on a hot day

49
Q

In a heat pump, when it’s in heating mode, how does it run?

A

Heating mode: the outdoor unit acts like evaporator coil and inside coil acts as condenser

This is possible because of the reversing valve.

50
Q

On a heat pump system the absorption and rejection areas switch depending on what?

A

The directional flow of refrigerant

51
Q

What is a solenoid valve?

A

An electro magnetic valve that is employed to control the flow of liquid or gas

Hvac (5 decks)

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