Nate Heat Pump

Front 1

R-22 vapor line diameters and lengths are typically specified for a:

Back 1

Vapor pressure drop that does not exceed 6 – 7 psi or 6°F

Front 2

The primary purpose of using flux when soldering copper or brass parts is to:

Back 2

Prevent oxidation.

Front 3

The water that results from a defrost cycle of an air to air heat pump (runoff) must:

Back 3

Drain off and away from the outdoor coil to prevent excessive ice can build up on the bottom of the coil and reduce capacity.

Front 4

The component used to reduce sound transmission and prevent water leaks of a packaged heat pump installed on a roof is:

Back 4

The curb gasket.

Front 5

On some installations, a heat pump indoor coil can be installed on an existing, operable, fossil fuel furnace.When this type of installation is done you need to add a control so that:

Back 5

~The furnace and heat pump do not operate at the same time in normal heating.

Front 6

When under a deep vacuum, a hermetic refrigeration compressor’s motor windings could be:

Back 6

Damaged if energized.

Front 7

In order for an evacuation to be considered complete:

Back 7

A heat pump refrigerant circuit should be evacuated to a vacuum pressure of 500 microns or below.

Front 8

A system is supplied from the factory with charge for a:

Back 8

15 foot line set.

Front 9

The data plate shows the required system charge to be 5 pounds 10 ounces.The line set uses a liquid line and is

Back 9

3/8 inch. And 25 feet long.

Front 10

The manufacturer’s instruction sheet specifies ________________ of refrigerant to be added for each added foot of refrigerant line length

Back 10

0.6 Ounces

Front 11

A system is supplied from the factory with charge for a:​ 15 foot line set.The data plate shows the required system charge to be 5 pounds 10 ounces.The line set uses a 3/8 inch liquid line and is 25 feet long.The manufacturer’s instruction sheet specifies 0.6 ounces of refrigerant to be added for each added foot of refrigerant line length so:

Back 11

~The total refrigerant charge for the system would be6 pounds.

Front 12

Drive slips are typically installed on the:

Back 12

Shorter sides of rectangular duct.

Front 13

To properly set a heat anticipator it is necessary to:

Back 13

Check the heating control circuit amperage draw.

Front 14

A heat pump operating in normal ice free conditions maintains a certain temperature difference between the outdoor coil temperature and the surrounding outdoor ambient:

Back 14

This temperature difference is referred to as coil TD.

Front 15

The smallest refrigerant leak that an electronic leak detector should be capable of sensing is:

Back 15

0.05 oz. per year.

Front 16

When checking the pressures in an operating system with a manifold gauge set:

Back 16

Refrigerant oil in a hose will have no effect on the gauge reading.

Front 17

At sea level, a gauge pressure of 35 psigis equal to an:

Back 17

Absolute pressure of 49.7 psia

Front 18

A technician measures the return air temperature of a 100,000 Btu output furnace to be 65°F and the supply side air temperature is 135°F:

Back 18

The CFM would be 1323.

Front 19

A residential supply diffuser that is noisy because of a loose vane is best serviced by:

Back 19

Replacing the diffuser.

Front 20

When performing preventive maintenance on a heat pump the technician should check the outdoor fan to be certain that the:

Back 20

Fan runs freely with no binding

Front 21

What is the effect of 170 volts supplied to a 208/230 volt compressor:

Back 21

Would cause a current increase and the motor may trip on overload.

Front 22

On a service call for a cooling problem with a heat pump, your inspections find a liquid line that has condensation on it:

Back 22

The most likely cause would be the liquid line is restricted.

Front 23

A reason for cool air complaints when a heat pump is operating in the heating cycle:

Back 23

Excessive supply air velocities.

Front 24

The following measurements are recorded on an operating heat pump system. The heat pump is operating with the compressor only with no auxiliary heat

Back 24

~Heat pump only supply air temperature 92°F~Heat pump only return air temperature 70°F~Outdoor temperature 54°F~Supply air temp. /auxiliary heat ON 115°F~Return air temp. /auxiliary heat ON 70°F~CFM 1228~The heating capacity of the unit in Btu/h would be 29,177 Btu/h

Front 25

A dirty or clogged air filter in an operating heat pump system can cause by:

Back 25

Inadequate heating

Front 26

To minimize noise problems in residential duct systems, what is the range (recommended to maximum) of design air velocity in the rectangular main supply trunk is:

Back 26

700 to 900 fpm.

Front 27

Proper ductwork connections and sealing is critical to good system performance.Conditions are:

Back 27

Return side air leak of 15% in a ventilated attic~2½ ton system rated at 1,000 CFM.~Attic Air 95°F

Front 28

A technician has the following conditions while checking a packaged heat pump in cooling.

Back 28

~The unit has a piston type metering device on both the indoor and outdoor coils.~Outdoor temperature 75°F~Superheat 55°F

Front 29

The effect of adding a charge to sub cooling is it:

Back 29

Increases it (sub cooling).

Front 30

When a capillary tube is overcharged you would get a:

Back 30

Low superheat and high sub cooling

Front 31

The effect of a low charge on the switchover operations of a reversing valve is the:

Back 31

Reversing valves are less likely to transfer if charge is low.

Front 32

A technician is working on a heat pump with a capacitor start-capacitor run compressor. On initial startup, the compressor hums momentarily and the shuts down on internal overload:

Back 32

The problem is too great a pressure difference on the compressor.

Front 33

A step down transformer has a rating of 40 VA. Its primary voltage is 120V with a secondary voltage of 24V. This transformer must not be connected to a load above a maximum current draw of:

Back 33

1.7 amps

Front 34

A bright red or orange glow from the resistance element in a duct heater:

Back 34

Indicates that the flow of air is insufficient.

Front 35

The outdoor fan on a heat pump stops during

Back 35

Defrost to minimize defrost time

Front 36

A capacitor start-capacitor run (CSCR) motor has an open run capacitor so it may start:

Back 36

But it draws a higher than normal running current.

Front 37

Bent vanes on a direct drive blower wheel in an air handler can cause:

Back 37

~Loss in airflow~Excessive motor wear~Increased noise

Front 38

A split system heat pump is using thermostatic expansion valves. The system performs properly in heating but in cooling the compressor pumps down:

Back 38

Which could mean the power element of the indoor expansion valve has lost its charge.

Front 39

Conditions that can cause a reduction from design capacity in a heat pump are an:

Back 39

Undersized vapor line

Front 40

Flash gas in the liquid line of any heat pump must be avoided.Liquid line flash gas can be caused by:

Back 40

Excessive liquid line length or lift.

Front 41

A symptom that a technician would expect on a heat pump system in the cooling mode if the check valve is leaking internally is a:

Back 41

Flooding of the indoor coil.

Front 42

A voltage reading across a closed contact in a 24V control circuit indicates:

Back 42

Pitted or dirty contacts.

Front 43

The first two checks typically made on an electronic control are:

Back 43

Presence of proper input signals.~Proper output voltages.

Front 44

In a low voltage circuit, a corroded wire-to-terminal connection acts in the circuit like:

Back 44

An additional resistor.

Front 45

The continuity of a fuse should be tested by

Back 45

Checking resistance with power off

Front 46

The first check made for most electrical troubleshooting is a:

Back 46

Voltage check of the supply line.

Front 47

To properly check an energized compressor circuit:

Back 47

The technician should use a VOM set for volts.

Front 48

The following conditions exist in a circuit that supplies power to three parallel loads:

Back 48

One load is resistive.

~One load is capacitive.

~One load is inductive.

Front 49

The technician is using an analog multimeter to check a run capacitor. With the meter set to ohms the needle swings toward zero and then slowly rises toward infinity:

Back 49

This tells the technician that the capacitor charges and discharges.

Front 50

If the technician believes that a hermetic compressor has a permanently open internal overload protector:

Back 50

The technician should test the compressor while it is cool.

Front 51

A control string is defined as two or more switch contacts connected in a circuit, or set of circuits, to control a load.In order to troubleshoot a load controlled by a control string:

Back 51

The technician must first check for proper voltage applied across the load.

Front 52

The technician suspects that an outdoor thermostat used to bring on auxiliary heat may be out of calibration. The thermostat is a close-on-fall type that is adjustable.One method for checking the thermostat calibration is to:

Back 52

Manually rotate the shaft until the thermostat closes and compare the dial setting to an accurate outdoor temperature reading plus 10°F.

Front 53

When changing out an evaporator coil the installer must be certain to:

Back 53

Plumb the cabinet so its sides are vertical.

Front 54

The recommended maximum external static pressure used for heating and cooling equipment with blowers for 5 ton of cooling or less is:

Back 54

~ 0.1 in W.C.~

Front 55

When a balancing check of a newly installed duct system the:

Back 55

Dampers should be open completely in all rooms.

Front 56

Operating sound is a consideration in the location of a condensing unit because:

Back 56

Excessive noise could be disruptive to the customer.

Front 57

A technician has determined a supply in a flexible duct system is leaking:

Back 57

All connections including inner and outer layers should be checked.

Front 58

Sensible heat ratio is:

Back 58

Sensible removed ÷ total heat removed.

Front 59

Service site conditions are:

Back 59

House feels “drafty” in cooling.~3½ ton split system.~High supply face velocities.~Ductwork is properly sized.~Total CFM 1400.

Front 60

A wet bulb reading that is very close to the dry bulb reading from the same instrument indicates:

Back 60

The relative humidity is very high.

Front 61

The following measurements would be needed to properly evaluate a complaint of “drafty” operation with a heating system are:

Back 61

System TD drop.~Static pressure.

Front 62

The kind of energy that the condenser removes from the refrigerant is:

Back 62

Sensible and latent heat.

Front 63

In a simple refrigerant system:

Back 63

The refrigerant boils in the evaporator.

Front 64

The common suction line on a heat pump is:

Back 64

Connected between the indoor coil and the compressor.

Front 65

There are two generally used methods for changing capacity on demand in a heat pump:

Back 65

One is to use a two speed compressor.~The other method is using a two stage thermostat.

Front 66

The three things that happen when a heat pump is cycled into the defrost mode are:

Back 66

The reversing valve switches to the cooling mode.~The outdoor fan is shut off and the auxiliary heat is energized.

Front 67

An extended plenum duct system is a:

Back 67

Single trunk extending in one or two directions with many branch ducts.

Front 68

The effect on supply airflow when static pressure on the return is reduced is:

Back 68

Airflow will be increased.

Front 69

The voltage most often used to power the outdoor unit in a residential system is:

Back 69

240V single phase.~

Front 70

Residential control or low voltage wiring normally is:

Back 70

~Shielded wired.

Front 71

If you increased suction pressure on a reciprocating compressor:

Back 71

The capacity would decrease.

Front 72

The refrigerants typically used in residential and light commercial pumps:

Back 72

Have a storage life of an indefinite length of time.

Front 73

A restricted drier can cause:

Back 73

A lower than normal suction pressure

Front 74

The blower motor type generally used on air handling equipment with capacities of 4,000 cfm or greater is:

Back 74

A belt driven with three phase.

Front 75

Electronic air cleaners can operate with internal voltages:

Back 75

As high as 5000 volts.

Front 76

A “cross break” made on all flat sides of any rectangular section of metal duct will:

Back 76

Increase rigidity and reduce vibration.

Front 77

The terms grille and register are often used interchangeably.There is a difference between these two components.The primary difference between a grille and a register is that:

Back 77

A register is equipped with an air volume control device.~A grille is not.

Front 78

Thermostatic expansion valves meter refrigerant flow to a coil to:

Back 78

Maintain superheated refrigerant leaving the coil.

Front 79

Some electromechanical type thermostats require connections to:

Of the low voltage transformer:

Back 79

Both the hot sideandCommon side

Because the display lights must be powered using both sides of the line.

Front 80

Disc type temperature limit controls, used to protect auxiliary heat elements from overheating are:

Back 80

Always auto reset by temperature.

Front 81

A disc-type, close-on –rise pressure control is being used as a loss-of-charge limit control on the liquid line of a heat pump. The control must sense a specified pressure within 15 seconds of a compressor start for the compressor to continue operation.If the cut-in setting of the control drifts lower:

Back 81

~The system is less likely to shut down as a result of a small leak.

Front 82

The sensor of an outdoor ambient thermostat for a heat pump system typically installed in the:

Back 82

Entering airstream to the outdoor coil.

Front 83

A high pressure limit control, used to shut down a compressor if condensing pressure becomes excessive is:

Back 83

Typically installed to sense compressor discharge line pressure

Front 84

Low pressure limit controls are often placed in the suction line of a heat pump for two purposes.They are to:

Back 84

Protect the compressor if suction pressure drops too low.&~To detect a loss of a charge.

Front 85

The function of a reversing valve is to:

Back 85

Provide heating and/or cooling.

Front 86

The relationship between inrush current and holding current of a relay coil is:

Back 86

Inrush current is always greater than Holding current.

Front 87

The timing specification of sequencers is often marked on the device using a code similar to H1-24 C45-75. The specification for this particular sequencer marked with this code is:

Back 87

Contacts close 1 to 24 seconds after coil is energized.~Contacts open 45 to 75 seconds after coil is de-energized.

Front 88

A seven day programmable thermostat can program a different daily schedule which is:

Back 88

Used for the next seven days only.

Front 89

The capability of electronic programmable room thermostat to reset the set point early so that the space temperature reaches a set temperature at a specific time is called:

Back 89

Computed recovery.

Front 90

An important reason for using electronic controls is:

Back 90

They can make decisions based on many inputs.

Front 91

One method used with electronic defrost controls to determine the need for defrost is

Back 91

To use two temperature sensors.

Front 92

One of the sensors measures coil temperature.​The other measures outdoor air temperature.The two temperatures used by the control to determine if a defrost is needed because:

Back 92

The lower temperature, the faster the outdoor coil builds up frost.

Front 93

When using a double (dual) element time-delay fuse with a 20 amp motor:

Back 93

The maximum fuse size should be 25 amps.

Front 94

According to fire protection codes, fire dampers should be used in:

Back 94

Any air duct that passes through all walls.or~Partitions of a light commercial installation.

Front 95

When the capacity of a heat pump in heating, measured in Btu’s, is the same at the heat loss of a structure:

Back 95

The system is said to have reached its balance point.

Front 96

Electronic air cleaners:

Back 96

Do not remove odors.

Front 97

A packaged heat pump must be:

Back 97

Mounted on a slab if its location is at grade level.

Front 98

Whenever possible, the slab should be:

Back 98

Located away from the structure to minimize noise

Front 99

A suction line accumulator should be used in a residential heat pump only when recommended by the manufacturer:

Back 99

If long refrigerant lines increase system charge over recommended maximum charge

Front 100

The measurement of a heat pumps efficiency is often stated using its:

Back 100

Coefficient of Performance” or COP.

Front 101

The COP of a heat pump is the:

Back 101

Heat pumps heat output in wattsdivided by~Total electrical input in watts

Front 102

A benefit in using electronic air cleaner is:

Back 102

Indoor air quality (IAQ) is improved.

Front 103

The purpose of calculating the heat loss at an outside design temperature is to:

Back 103

Select the appropriate equipment based on Btu output.

Front 104

The thermal balance point of a dual fuel heat pump is:

Back 104

The outdoor conditions at which the capacity of auxiliary heat alone matches the heating load

Front 105

The minimum circuit amp listed on a units’ data plate is used to:

Back 105

~Determine the max fuse or circuit breaker size.

Front 106

Heat pumps are particularly sized based on:

Back 106

The cooling load.

Front 107

The effective method of reducing sound when AHU is located in a closet is to:

Back 107

Use vibration isolators.

Front 108

When wiring a 20 amp FLA motor, the minimum amp fuse or circuit breaker:

Back 108

Should be 25.

Front 109

The typical staging of a two stage HP system uses the:

Back 109

Deviation of the t-stat setting to determine when to engage each stage.

Front 110

The purpose of a sequencer in a HP with an AUX 20 kW electric heater is to:

Back 110

Energize one or two elements and the blower then energize the other elements in timed intervals.

Front 111

In a HP circuit, an open check valve is used to:

Back 111

By-pass refrigerant flow around the metering device.

Front 112

The forward curve centrifugal fan is the:

Back 112

Most commonly used type in residential systems.

Front 113

In A reversing valve:

Back 113

The single pipe is connected to the compressor discharge.

Front 114

The airflow path of with an outdoor unit pull through coil is:

Back 114

Air moves from the outside to the inside.

Front 115

Economizer systems close the outdoor air vent to a:

Back 115

Preset minimum when outdoor air enthalpy exceeds the set point.

Front 116

Condensation on vapor lines is a:

Back 116

Concern when the lines are routed inside a wall.

Front 117

Refrigerant sub-cooling is measured:

Back 117

Between~Refrigerant Condensing Temp&~Liquid line temp

Front 118

In a single zone system; if a customer complains of feeling damp or sticky the cause could be:

Back 118

Unconditioned air being pulled into the duct work through holes in the duct.

Front 119

When performing indoor air balancing tests the t-stat should be set to:

Back 119

Bring on the indoor fan on mid-high speed.

Front 120

Most manufacturers recommend the:

Back 120

Smallest allowable t-stat wire at~ 18 AWG.~

Front 121

Checking voltage input to a compressor should take place at the:

Back 121

Load side of the contactor.

Front 122

HP unit; 1st and 2nd stage appear to be calling, compressor runs but not electric heater:

Back 122

This is due to second stage being open.

Front 123

After compressor burn out:

Back 123

Test the oil for acidity levels.

Front 124

Manufacturers recommend that the most acceptable method of attaching line sets to the AHU is:

Back 124

Utilizing brazing alloy.

Front 125

There are more circuits in a HP outdoor coil than in an A/C outdoor coil to:

Back 125

Minimize refrigerant pressure drop.

Front 126

Inefficient voltage or current to a solenoid will result in:

Back 126

Vibration or chatter of the solenoid.

Front 127

A compressor that is suspected to be grounded to its’ housing should be checked for:

Back 127

Continuity from the terminal windings to ground.

Front 128

The coil of a potential relay is connected to:

Back 128

The common and start terminals of a compressor.

Front 129

When the load on a HP in cooling mode decreases:

Back 129

Suction pressure increases.&~Discharge pressure decreases.

Front 130

The measurements needed to find suction superheat are:

Back 130

~Suction pressure&~Suction line temperature.

Front 131

The purpose of an auto change over switch on a t-stat is to:

Back 131

Allow automatic change over between heating and cooling.

Front 132

Undersized duct work will often cause:

Back 132

High noise levels~High air quantity~High static pressures.

Front 133

Determining voltage drop at the outdoor unit requires:

Back 133

Checking voltage feed with the outdoor unit not running&~Then with the outdoor unit running.

Front 134

A manometer is used to:

Back 134

Measure static duct pressure.

Front 135

A system that has been evacuated to 500 microns:

Back 135

Rises immediately and at a constant rate after the vacuum pump has been shut off~Due to a leak in the system.

Front 136

To obtain an accurate refrigerant temperature on a horizontal suction line that is 1 1/8” or larger:

Back 136

The TXV sensing bulb should be located at4 or 8 o’clock on the pipe.

Front 137

The primary consideration when bending soft copper to any radius is the:

Back 137

Cross sectional area must not be significantly reduced.