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PPT Flashcards

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1
Q

Reverse-Cycle Refrigeration

  1. Air-conditioning equipment can only pump heat in ____ direction
  2. Heat pumps can heat two ways;
    - into as well as out of a ______
    - Also having a four-way ________ valve
    - These valves are used to switch the unit between _______ and _______ modes
A
  1. one

2. structure, reversing, heating and cooling

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2
Q

Heat Sources For Winter:

  1. Air conditioners pump heat from low temperature inside
    the structure to a higher temperature outside the house
  2. At 0F outside air temp, there is still __% usable heat in the air
  3. The heat pump removes ____ from the outside air in the winter and deposits it in the conditioned space to heat it; an air-to-air heat pump
A
  1. 85%

3. heat

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3
Q

The Four-Way Reversing Valve

  1. Allows heat pump to pump heat in ___ directions
  2. Diverts heat-laden discharge gas to either ____ or cool in conditioned space
  3. Refrigerant is directed from the _______ to the indoor coil in the heating mode
  4. Refrigerant is directed from the compressor to the ______ coil in cooling mode
A
  1. two
  2. heat
  3. compressor
  4. outdoor
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4
Q

The Four-Way Reversing Valve: Control and Operation

  1. Controlled by the space temperature _________
  2. Four port valve that has a slide mechanism in it:
    - Position of the slide determines the mode of operation: heating or cooling
    - Smaller, direct-acting, four way reversing valves
    - pressure difference pushes the slide mechanism
A

thermostat

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5
Q

What terminal is a conventional heat pump wired to?

A

B

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6
Q

What terminal is a non-conventional heat pump wired to?

A

O

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7
Q

Default/fail to O means ?

A

heating

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8
Q

Gas line in heat pump:

  1. HIGH temp superheated gas means the unit is in what mode?
  2. LOW temp superheated gas means the unit is in what mode?
A
  1. heating mode

2. cooling mode

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9
Q

Air Coils:

  1. circulates _______
  2. absorb heat from or release heat to ___
  3. Fins increase the heat _________ surface area
A
  1. refrigerant
  2. air
  3. exchanging
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10
Q

Ground Coils: Uncommon*

  1. Underground tubing through which refrigerant is circulated in ground-source heat pump
  2. outdoor coil for direct-exchange heat pump
  3. difficult to troubleshoot or ______
A
  1. repair
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11
Q

Water Coils:

  1. Heat transfers between refrigerant from indoor coil and water from water loop
  2. Installed near indoor ____
  3. Refrigerant and water pumped in separate but _______ tubes
A
  1. coil

3. adjacent

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12
Q

Water Loop:

  1. Tubing running to and from water _____
  2. Tubing is submerged in ______
  3. Used in closed-loop water-based systems
  4. Tubing water does not mix with body of _____ or refrigerant
A
  1. coil
  2. water
  3. water
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13
Q

Common Water-Based Solutions:

  1. Salts; name two
  2. Glycols; name two
  3. Alcohols; name two
A
  1. calcium chloride, sodium chloride
  2. Propylene glycol, ethylene glycol
  3. methyl alcohol, ethyl alcohol
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14
Q

Ground Loops:

  1. Tubing running to and from water coil _________
  2. Transfers heat between water coil and ______
  3. Can be horizontal or vertical
  4. can run in series or with ________ branches
A
  1. underground
  2. ground
  3. parallel
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15
Q

Auxiliary Heat: Balance point:

  1. When heat pump output _____ heat loss of the conditioned space
  2. If heat loss is greater than heat production, ________heat is required
A
  1. equals

2. auxiliary

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16
Q

Auxiliary Heat:

  1. Supplementary heat source in order to temper air
  2. Usually electric resistance heating coils, but it could be a gas-fired or oil-fired heating system
  3. Also used during reverse cycle ______ and for emergency heat operation
A
  1. defrost
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17
Q

During defrost of outdoor coil the unit will go into cooling mode in order to bring hot gas back to outdoor unit in order to melt the ___

A

ice

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18
Q

The Air-to-Air Heat Pump:

  1. The air-to-air heat pump resembles the central air-conditioning system
  2. Changes in terminology in a heat pump system:
    - the coil that serves the inside of the house is called the ______ coil
    - the coil that is located outside the house is called the _____ coil
  3. Mode determined by the direction in which the _________ flows
A
  1. indoor, outdoor

3. refrigerant

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19
Q

Refrigerant Line Identification:

  1. The larger line is called the gas line because it always carries ___
  2. The suction line in the cooling mode and the discharge line in the heating mode
  3. The smaller line is called the liquid line because only liquid ________ travels through it
  4. The liquid flow toward the inside unit in ______ and towards the outside unit in _______
A
  1. gas
  2. refrigerant
  3. summer, winter
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20
Q

Metering Devices:

  1. Metering devices needed at _____ heat exchanger
  2. Types used in heat pumps;

_____-orifice devies
_________ tubes
____
Flow ____ pistons

A
  1. each

2. fixed orifice, capillary, TXVs, flow check

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21
Q

Metering Devices:

  1. Specially designed for ____ ____ applications
  2. There must be a metering device at the ______ unit in the heating mode
  3. There must be a metering device at the indoor coil in _______ mode
A
  1. heat pumps
  2. outdoor
  3. cooling
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22
Q

Thermostatic Expansion Valves:

  1. Check valves are piped parallel to the TXV to allow refrigerant to bypass the control when needed
    - in cooling mode, the valve needs to meter the flow of liquid refrigerant into the indoor coil
    - in heating mode, the liquid needs to move freely toward the outdoor unit
  2. A vapour-charged TXV with a limited charge in the bulb usually used
  3. Bidirectional thermostatic expansion valves have a _____ valve built in
A
  1. check
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23
Q

In any type of hot pull down you need an ___ TXV

A

MOP - maximum operating pressure

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24
Q

Thermostatic expansion valves:

  1. Generally allow flow in only ___ direction
  2. Solutions for more flow directions;
    Check valves running ______ to each TXV
  3. Must have ___ compatible with coil and compressor
A
  1. one
  2. parallel
  3. MOP
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25
Q

The Capillary Tube:

  1. Often encountered on older pieces of equipment
  2. Will allow refrigerant flow to ____ ways
  3. Typically two capillary tubes are used
  4. Check valves are used to reverse flow but cannot meter flow based on ________ outlet temp (SH)
  5. Must be sized for specific flow amount
  6. Different sizes used for ______ and outdoor coils
A
  1. both
  2. evaporator
  3. indoor
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26
Q

Combination of Metering Devices:

  1. Uses the capillary tube at the indoor coil
    - used in the ______ mode
    - Load is relatively _______ in the warmer months
  2. Uses thermostatic expansion valve at the outdoor coil
    used in the _______ mode
    - allows system to reach maximum ________ quickly
A
  1. cooling, constant

2. heating, efficiency

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27
Q

Electronic Expansion Devices:

  1. Can meter refrigerant in ____ directions
  2. If indoor and outdoor coils are close together, ____ device can be used
  3. The correct superheat will be maintained in both heating and cooing modes
A
  1. both

2. one

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28
Q

Orifice metering devices:

  1. used in conjunction with _____ valves
  2. One device is located at each ____
  3. The bore at the indoor coil is ______ than the bore at the outdoor oil
  4. Normally used with a ______ filter drier
A
  1. check
  2. coil
  3. larger
  4. bi-flow
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29
Q

Flow Check Pistons:

  1. Meters refrigerant flow in ___ direction
  2. Allows refrigerant to flow ______ and unrestricted in the other direction
  3. systems use two flow check pistons oriented in opposite directions
A
  1. one

2. freely

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30
Q

Liquid Line Accessories:

  1. Two standard filter driers can be used on systems with check valves:
    - only one drier In the circuit at a time
    - they are installed with arrows pointing in the same direction as the _____ valves
  2. Bi-Flow filter driers: use this for heat pumps
    - two driers in one
    - designed for ____ pump applications
A
  1. check

2. heat pump

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31
Q

Compressors:

  1. Operate at ______ ambient temperatures than air-conditioning compressors
  2. Designed to handle liquid _______
    - slow start-up routines
    - stronger valves
    - accumulators and two-way filter-driers
    - crankcase heaters
A
  1. lower

2. liquid slugging

32
Q

For low temp compressors the bore size is

A

larger

33
Q

For medium temp compressors the bore size will be smaller and high temp bore size even

A

smaller

34
Q

Heat pump compressors are designed to handle overloads in pressure during defrost mode so they do not need crankcase ______ regulators

A

pressure

35
Q

Application of the Air-to-Air Heat Pump:

  1. usually installed in ______ climates
    - In winter, the outdoor coil ______ heat
  2. The system loses capacity as the outside temperature ____
A
  1. milder, absorbs

2. drops

36
Q

Auxiliary Heat:

  1. Required when the heat pump cannot provide all the heat a structure needs
    - The heat pump is the primary heat source
    - auxiliary heat could be ______, oil or gas
    - electric heat is the most common auxiliary heat used
    - as the outside temp drops, the structure requires more heat
A

electric

37
Q

Balance Point:

  1. Balance point occurs when the heat pump can pump in exactly as much heat as the structure is ______ out
  2. Above the balance point, the heat pump will _____ on and off
  3. Below the balance point, the heat pump will run _________ and second stage (auxiliary) heat will be energized
A
  1. leaking
  2. cycle
  3. continuously
38
Q

Heat Pump Efficiency:

  1. Methods for gauging heat pump efficiency
    - _____ efficiency ratio (EER)
    - ________ energy efficiency ratio (SEER)
    - ________ seasonal performance factor (HSPF)
    - Coefficient of performance (COP)
A

energy, seasonal, heating

39
Q

Coefficient of performance:

  1. One watt of usable heat is supplied for each watt of energy purchased
    - 100% efficient, COP is 1:1
  2. Air-to-air heat pumps: a COP of 3:5:1
    - one watt of electrical energy used by the compressor can furnish ____ watts of usable heat
A
  1. 3.5 watts
40
Q

Coefficient of Performance: Effect of Temperature;

  1. High COP only occurs during ______ outdoor winter temperatures
  2. A heat pumps COP falls as the outdoor temperature ____
  3. A typical air-to-air heat pump has a COP of 1:5:1 at _F
A
  1. higher
  2. falls
  3. 0F
41
Q

The Defrost Cycle: SEER and HSPF

  1. Seasonal energy efficiency ratio (SEER)
    - the total cooling output for the system divided by the actual power _____
  2. Heating Seasonal Performance Factor HSPF)
    - applies to particular piece of equipment
  3. SEER and HSPF ratings are results of federal _____ _______
A
  1. input

3. energy policies

42
Q

The Indoor Unit:

  1. The part of the system that circulates the ___ within the structure
  2. Contains the fan and coil and often the ______ strip heaters
  3. The refrigerant coil must be located in the _______ before the auxiliary heating coil
  4. The indoor unit may be a ___ or oil fired furnace
A
  1. air
  2. electric
  3. airstream
  4. gas
43
Q

Coefficient of Performance: Water-to-air heat pumps;

  1. Some manufacturers have controls to shut off the ________ at temperatures of 0-10F
  2. Water-to-air heat pumps might not need auxiliary heat since the heat source (water). temperature is
  3. Water-to-air heat pumps have a ____ rating as high as 4:1
A
  1. compressor
  2. constant
  3. COP
44
Q

The Split-Type, Air -to-Air Heat Pump:

  1. Air-to-Air systems can be split or _______ type
  2. Both heat pumps and cooling air-conditioning systems look identical
  3. Split systems require the installation of the gas and liquid refrigerant lines to connect the ______ and outdoor units
A
  1. package

3. indoor

45
Q

The Indoor Unit: Furnace Types;

  1. If gas or oil furnace is the indoor unit, the coil must be relocated in the outlet airstream of the furnace
  2. If a gas or oil furnace is used, the heat pump will ___ operate while they run
  3. Heat pumps added to electric furnaces should have the coil located ____ the heat strips
A
  1. not

3. after

46
Q

Temperature of the Conditioned Air:

  1. Temperature of the air supplied by a HP are not as hot as with gas and oil-fired equipment
  2. Leaving air temps are in the ___F range
  3. Supply air temperature will ____ when outside air temperature drops
  4. Proper air distribution can help reduce “____” complaints
A
  1. 100F
  2. fall
  3. draft
47
Q

The Outdoor Unit:

  1. Must have good air conditions around it.
    - prevailing winds affect ________
    - In the winter, outdoor coil will collect moisture that ______
    - Outdoor coil should be installed so it raises above the ground ___ to allow defrost water to run to the ground
    - A defrost system defrosts the ___ from the outdoor coil
A
  • performance
  • freezes
  • pad
  • ice
48
Q

Package Air-to-Air Heat Pumps:

  1. Has all the sealed system and electrical components in one ______
  2. Works much the same way as a packaged air-conditioning unit
  3. Can accept different electric heat sizes
  4. Require that ductwork be run right up to the ____
  5. Supply and return ductwork must be ________
A
  1. housing
  2. unit
  3. insulated
49
Q

What does Y control in a heat pump?

A

the compressor to allow for cooling

50
Q

Controls for Air-to-Air Heat Pumps:

  1. Controls are ______ than other heating/cooling equipment
  2. In a heat pump, there are two heating systems and one cooling system
  3. Auxiliary heating system must be operated as a system by itself in case the heat pump _____
  4. Auxiliary heat is referred to as ________ heat when used because of heat pump failure
A
  1. different
  2. fails
  3. emergency
51
Q

Controls for Air-to-Air Heat Pumps:
thermostat

  1. The space thermostat is the key to controlling the system
  2. Normally, a ____-stage heating and two-stage cooling thermostat is used
A

two

52
Q

Controls for Air-to-Air Heat Pump: Cooling Cycle Control;

  1. Automatic changeover thermostat
    - Changes between ______/_______ modes
A

heating/cooling

53
Q

Controls for Air-to-Air Heat Pumps: Space Heating control;

  1. Space heating control
    - thermostat controls compressor, outdoor fan motor, and ______ fan motor operation
    - Excessively cold temperatures energizes _______-stage heat
    - Second-stage heat _____ on and off to assist the heat pump
A
  • indoor
  • second
  • cycles
54
Q

Controls for Air-to-Air Heat Pumps:
Space Heating controls cont’d

  1. Balance point: point at which the heat pump can satisfy the load without ______ down; may be multiple
  2. Electric Heaters are energized at different temperatures:
    - The goal is to only energize enough electric strip heaters as necessary to help the heat pump reach and maintain the desired space temp
A
  1. shutting
55
Q

Controls for Air-to-Air Heat Pumps: Electronic Thermostats;

  1. Heat anticipator:
    - found on heat pump thermostats an conventional thermostats
    - most heat pump thermostats come with ____
  2. Electronic thermostats:
    - most have thermistors for heat-sensing, which responds _____ to temperature change
A
  1. two

2. faster

56
Q

The Defrost Cycle:

  1. Defrosts ice from outside coil during heating mode
    - when the outside temp drops the evaporator saturation temp can drop below __F
    - The outdoor coil can begin to freeze; system performance ______
  2. The need for defrost varies depending on outside air temperatures and conditions:
    - the more moisture in the air, the more _____ that forms on coil
A
  1. reduced

2. frost

57
Q

The Defrost Cycle: How is defrost accomplished?

  1. By de-energizing the outdoor fan and dour-way reversing valve switches into _______ mode
  2. One stage of strip heat is turned on and system will ____/_____ at the same time
A
  1. cooling

2. heat/cool

58
Q

Initiating the defrost cycle:

  1. manufacturers design systems to start defrost when frost affects _______
  2. Some use ____ and ________ initiated system,s
  3. Cylic is typically ___ minutes
A
  1. performance
  2. time and temperature
  3. 90 mintes
59
Q

Initiating the defrost cycle: air pressure switch initiated

  1. Measures the air pressure drop across the outdoor coil
    - When the unit begins to accumulate ice, a pressure drop occurs and the air with contacts _____
  2. The combo of time and temp only ensures that time has passed and the coil is cold enough to accumulate _____
A
  1. close

2. ice

60
Q

The Defrost Cycle: Terminating defrost;

  1. ____, _____, and pressure can all be used to terminate defrost
  2. Temperature sensors used for the defrosting function will open at __F
  3. __ minutes is the normal maximum time allowed for defrost cycle
A
  1. time, temp
  2. 50F
  3. 10 mintes
61
Q

The Defrost Cycle: Electronic Control of Defrost;

  1. Electronic control of defrost
    - electronic timers and thermistors used to control _____
    - More accurate control than non-electric methods
    - can incorporate _____ and temperature features into a single unit
  2. Demand initiation when coil has reached __ to __% frosted over condition
    - sensing the diff between the coil temp and ambient temp
    - measuring the pressure drop across the coil
    - sensing the coil temp
A
  1. defrost, time

2. 50-60%,

62
Q

Indoor Fan Motor Control:

  1. With a heat pump, the blower must start at the beginning of the cycle
    - controlled by the _______
    - the indoor blower is started with the blower terminal, often labeled __
    - The compressor operates whenever the unit is calling for cooling or heating
A
  1. thermostat, G,
63
Q

Second-Stage Electric Heat:

  1. Accomplished with an _______ furnace with a heat pump coil for cooling and heating
  2. Required to _____ the heat pump when it cannot provide all the heat the structure needs
  3. Also used as ________ heat when the heat pump needs service
  4. Heaters also energized during defrost
A
  1. electric
  2. help
  3. emergency
64
Q

Servicing the Air-to-Air Heat Pump:

  1. Much like servicing a ______ system
  2. During the cooling mode, operates as a high-temperature refrigeration system
  3. During the heating mode, operates as low-temperature refrigeration system
  4. Servicing of the system is divided into ________ and mechanical
A
  1. refrigeration

4. electrical, and mechanical

65
Q

Troubleshooting the Electrical System:

  1. Typical electrical problems:
    - indoor blower motor and outdoor fan motor
    - compressor contractor, fan relays
    - defrost relay
    - compressor
    - reversing valve solenoid
    - electric strip heaters
    - general wiring problems
A

remember*

66
Q

Troubleshooting Mechanical Problems:

  1. Can be hard to identify in a heat pump, particularly in ______ operation
  2. _______ operation of a heat pump is similar to an air-conditioning unit
  3. Mechanical problems are solved with gauge manifolds, wet-bulb and dry-bulb thermometers, and air-measuring instruments
A
  1. winter

2. summer

67
Q

Troubleshooting the Four-Way Reversing Valve:

  1. Common problems: ____valve, defective coil, and internal leaks
  2. Check to see if coil is _______, a warm coil indicates power is being supplied, place a screwdriver on coil surface to sense magnetic field
  3. Check for voltage supplied to the coil
A
  1. stuck

2. energized

68
Q

Troubleshooting the Compressor:

  1. A reliable test will tell whether the compressor is pumping at near capacity: operate the unit in _______ mode while blocking the _____ until head pressure is 440psig and the suction pressure is 118psig
  2. amperage should be at close to ___ load
  3. large inefficiencies indicate that the compressor is leaking ______
A
  1. cooling, airflow
  2. full
  3. internally
69
Q

Checking the Charge:

  1. Most heat pumps have a _______ refrigerant charge
  2. Do not install a standard ______ manifold each time you suspect a problem.
  3. When a heat pump has a partial charge;
    - leak check system before charging
    - some manufacturers recommend evacuation and recharge
A
  1. critical

2. gauge manifold

70
Q

Special Applications for Heat Pumps; Use of oil or gas furnaces for auxiliary heat

  1. more efficiency than auxiliary _____ heat
  2. heat pump coil must be installed _______ of oil or gas heat exchanger
  3. the air must flow through the furnace heat exchanger before the heat pump coil
  4. the oil or gas furnace must ___ operate at the same time that the heat pump is operating
A
  1. electric
  2. downstream
  3. NOT
71
Q

Heat Pumps Using Scroll Compressors:

  1. ideally suited for heat pump application because of its pumping characteristics
  2. Scrolls do not lose as much ______ as reciprocating compressors
  3. scroll compressor pressures are about the same as ________ compressors
  4. scroll compressors are discharge gas ______
A
  1. capacity
  2. reciprocating
  3. cooled
72
Q

Heat Pumps Using Scroll Compressors: Other features;

  1. Have a check valve in the discharge leaving the compressor to prevent pressures from equalizing through the compressor during the off cycle
  2. normally do not require suction-line _______ because they are not as sensitive to liquid flood back
A
  1. accumulator
73
Q

Heat Pump Systems with Variable-Speed Motors:

  1. Used for the compressor and both fan motors as a method to improve system _______ in heat pump systems
  2. sized closer to the heating _______ of the structure at full load; will run at part load and reduced power in warmer months
A
  1. efficiency

2. requirements

74
Q

In BC, how are our heat pumps manufactured and configured?

A

Default to heating, non-conventional

75
Q

How to improve humidity in a heat pump?

A

lower fan speed in cooling and high speed in heating

76
Q

Why is oversizing a heat pump bad?

A

higher cost of equipment, installation, and less then ideal summer humidity control

Level 2: Heat Pumps (3 decks)

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