NATE Air-to-Air Heat Pump Installation Specialty

An air-to-air heat pump moves heat between the indoor and outdoor air. During the heating mode, which coil functions as the evaporator?

• AThe indoor coil
• BThe outdoor coil
• CThe reversing valve
• DThe accumulator

NATE limits the air-to-air heat pump specialty to systems with a cooling capacity of what size or smaller?

• A10 tons
• B20 tons
• C30 tons
• D50 tons

When sizing a heat pump for a home, which industry procedure is used to calculate the building's heating and cooling load?

• AACCA Manual D
• BACCA Manual J
• CACCA Manual S
• DACCA Manual T

After completing a Manual J load calculation, which procedure is used to select properly sized heat pump equipment?

• AManual J
• BManual D
• CManual S
• DManual N

The outdoor temperature at which a heat pump's heating capacity exactly equals the building's heat loss is called the:

• ASetpoint temperature
• BBalance point
• CDesign temperature
• DDefrost termination point

A heat pump's heating efficiency rating that reflects seasonal performance is the:

• ASEER2
• BHSPF2
• CEER2
• DAFUE

Compared with electric resistance heat, a heat pump in heating mode is more efficient because it:

• AGenerates heat directly from electricity at the indoor coil
• BMoves existing heat from outdoor air rather than creating it
• CBurns refrigerant to produce heat
• DUses combustion air for the heating process

A dual-fuel (hybrid) heat pump system pairs an air-to-air heat pump with which supplemental heat source?

• AA gas or oil furnace
• BElectric resistance strips only
• CA second heat pump
• DA solar collector

On a typical R-410A heat pump nameplate, the refrigerant charge listed by the manufacturer is the factory charge for a line set up to what reference length?

• A5 feet
• B15 feet
• C25 feet
• D100 feet

Which document should the installer always consult for model-specific clearances, charge, and wiring before installing a heat pump?

• AThe National Electrical Code only
• BThe manufacturer's installation instructions
• CThe previous unit's nameplate
• DA generic HVAC textbook

When locating an outdoor heat pump unit, adequate clearance around the coil is required primarily to:

• AReduce the refrigerant charge needed
• BEnsure proper airflow across the outdoor coil
• CLower the compressor amperage
• DPrevent reversing valve chatter

An outdoor heat pump unit should be mounted on a pad raised above grade primarily to:

• AIncrease the airflow rate
• BKeep the coil above accumulating snow, ice, and defrost runoff
• CReduce the refrigerant temperature
• DComply with duct sealing codes

While brazing the line set connections, an inert gas should flow through the tubing to prevent oxidation. Which gas is used?

• AOxygen
• BAcetylene
• CDry nitrogen
• DCarbon dioxide

After brazing and pressure testing, a heat pump system should be evacuated to remove moisture and non-condensables. The target deep vacuum is typically below:

• A5,000 microns
• B1,500 microns
• C500 microns
• D0 microns (perfect vacuum)

A vacuum decay (rise) test after evacuation is used to determine whether the system:

• AHas the correct refrigerant charge
• BStill contains a leak or residual moisture
• CHas proper airflow
• DIs correctly wired

The filter drier installed in a heat pump's refrigerant circuit must be a bi-flow type because:

• AThe refrigerant flows in both directions as the system reverses
• BIt filters air as well as refrigerant
• CIt reduces compressor noise
• DIt eliminates the need for an accumulator

An accumulator is installed in the suction line of a heat pump primarily to:

• AAdd subcooling to the liquid line
• BProtect the compressor from liquid refrigerant floodback
• CFilter moisture from the vapor
• DMeter refrigerant into the evaporator

When routing the refrigerant line set, the suction (vapor) line should be insulated to:

• AIncrease its pressure
• BPrevent heat gain/loss and condensation on the line
• CSlow the refrigerant velocity
• DReplace the need for a P-trap

When a heat pump line set is run longer than the manufacturer's standard length, the installer must:

• AReduce the system airflow
• BAdd refrigerant by weight per the manufacturer's per-foot specification
• CInstall a second compressor
• DSwitch to a fixed orifice metering device

Why is the indoor coil (air handler or coil cabinet) for a heat pump typically larger than a comparable cooling-only AC coil?

• ATo hold more refrigerant oil
• BTo provide adequate surface area when the indoor coil acts as the condenser in heating
• CTo reduce static pressure
• DTo allow a smaller blower motor

Proper matched indoor airflow for a heat pump in heating mode is generally required to be:

• AMuch lower than cooling airflow
• BApproximately equal to or greater than the cooling airflow requirement
• CZero during defrost
• DSet only by the thermostat fan switch

The condensate drain from a heat pump's indoor coil must be installed with a trap when the coil is on the:

• APositive-pressure (blow-through) side requiring no trap
• BNegative-pressure (draw-through) side of the blower
• COutdoor unit base pan
• DReturn air filter rack

Because the outdoor coil produces condensate water during the defrost cycle, the installer must ensure:

• AThe condensate is piped to the indoor drain
• BDefrost water can drain freely away from the base of the unit
• CThe water is recovered into the refrigerant
• DA second TXV is added

When making flare connections on a mini-split or line set, the installer should tighten the flare nut to the manufacturer's specified:

• ATorque value with a torque wrench
• BHand-tight only
• CMaximum force possible
• DQuarter turn past finger tight in all cases

A disconnect switch installed at the outdoor heat pump unit is required so that:

• AThe thermostat can be calibrated
• BPower can be safely isolated near the equipment for service
• CThe refrigerant can be recovered
• DThe defrost timer is reset

On a standard heat pump thermostat, the terminal that controls the reversing valve and is energized in cooling mode on most brands is:

• AThe W terminal
• BThe O terminal
• CThe B terminal
• DThe G terminal

A heat pump thermostat with an O terminal energized in cooling, but the system blows cold air on a call for heat. The most likely wiring cause is:

• AThe G terminal is loose
• BThe reversing valve is wired to energize in heating instead of cooling (O/B reversed)
• CThe C wire is missing
• DThe W2 terminal is jumpered

On a heat pump thermostat, the auxiliary/emergency electric heat is typically controlled by which terminal(s)?

• AO and B
• BW (W1/W2) for auxiliary and emergency heat
• CG and Y
• DR and C

The Y terminal on a heat pump thermostat controls the:

• AIndoor blower
• BCompressor contactor
• CReversing valve
• DAuxiliary heat relay

A modern communicating or Wi-Fi heat pump thermostat usually requires which wire to provide continuous 24 V power?

• AThe G wire
• BThe C (common) wire
• CThe O wire
• DThe Y2 wire

An outdoor temperature sensor wired to a heat pump's controls is commonly used to:

• AMeasure refrigerant pressure
• BLock out compressor or auxiliary heat operation outside set temperature thresholds
• CControl the indoor humidity
• DSet the thermostat backlight

The low-voltage control circuit on a residential heat pump typically operates at:

• A120 VAC
• B240 VAC
• C24 VAC
• D12 VDC

When sizing the branch circuit and overcurrent protection for a heat pump, the installer should use the nameplate's:

• ARLA only
• BMinimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP)
• CFLA of the indoor blower only
• DLRA value

A heat pump contactor's coil that pulls in the line-voltage contacts to start the compressor is energized by:

• A240 VAC directly from the breaker
• BThe 24 VAC control circuit on a Y call
• CThe defrost board's O output
• DThe condensate float switch

When connecting electric heat strips as part of a heat pump installation, sequencers or staging relays are used primarily to:

• AIncrease the strip resistance
• BBring the heating elements on in stages to limit inrush current
• CReverse the refrigerant flow
• DCool the elements

Electric heat strips installed in a heat pump air handler must include a safety device that opens on overheating, known as a:

• AReversing valve
• BHigh-limit (thermal cutout) switch
• CTXV
• DCapacitor

A heat pump using a thermostatic expansion valve (TXV) as its metering device is typically charged by the:

• ASuperheat method
• BSubcooling method
• CWeighing the line set only
• DFrost-line method

A heat pump using a fixed orifice (piston) metering device is typically charged using the:

• ASubcooling method
• BSuperheat method
• CTotal-weight method only
• DHead-pressure method

Subcooling is defined as the number of degrees the liquid refrigerant is cooled:

• AAbove its saturation temperature
• BBelow its saturation (condensing) temperature at the measured pressure
• CBelow ambient air temperature
• DAbove the suction-line temperature

Superheat is the number of degrees the refrigerant vapor is heated:

• ABelow its saturation temperature
• BAbove its saturation (boiling) temperature at the measured pressure
• CAbove the condenser temperature
• DBelow ambient temperature

The standard residential heat pump refrigerant that replaced R-22 and is widely installed today is:

• AR-12
• BR-410A
• CR-134a
• DR-502

Because R-410A is a near-azeotropic blend, it must always be charged into the system as a:

• AVapor from the top of the cylinder
• BLiquid from the cylinder (often through a metering device)
• CEither liquid or vapor, no difference
• DGas only, never liquid

The most accurate way to charge a new heat pump installation when the line set length is known is to:

• ACharge until the suction line frosts
• BWeigh in the factory charge plus the calculated line-set adjustment, then verify by subco…
• CAdd refrigerant until head pressure reads 250 psi
• DMatch the old system's gauge readings

When verifying the charge on a TXV heat pump during installation, charging is most reliably done in which mode?

• AHeating mode at design conditions
• BCooling mode using the subcooling target
• CDefrost mode
• DEmergency heat mode

A typical target subcooling value for a properly charged residential TXV heat pump in cooling is approximately:

• A0 to 2 degrees F
• B10 to 12 degrees F
• C25 to 30 degrees F
• D40 to 45 degrees F

Before opening the service valves to release the factory charge into the line set and indoor coil, the installer must have:

• ARun the compressor for 10 minutes
• BEvacuated and leak-checked the field-connected lines and coil
• CEnergized the heat strips
• DSet the thermostat to emergency heat