Heat Pumps Final

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Electric heat has performance ratio of?

1:1

Electric heat element is what type of load device?

Resistive

How many BTU’s will a 3 kW heat element produce at 240 volts?

10,242

An electric furnace has no need for?

All the above

The switching action of a properly operating heating thermostat will?

Both A & B open on rise close on drop

The purpose of a sequencer is to?

Avoid a certain power load

What is the backup safety device for the high limit switch on electric strip heat?

Thermal fuse element (fusible link)

What terminal on a thermostat is energized on a call for auxiliary heat?

W2

What terminal on thermostat is used if reversing valve is energized on a call for heat?

B

The indoor coil is usually mounted in the airstream ______ the auxiliary heat strips?

Before

The heat pump utilizes what type of filter drier?

One biflow

During the defrost cycle the heat pump switches to what operating mode?

D. Both B & C

The defrost cycle can be initiated by?

C. Either A or B

What device shuts off outdoor fan during defrost?

Any of the above

What 3 things happen to most air to air heat pumps during defrost?

What 3 things happen to most air to air heat pumps during defrost?

What functions to the Ranco E15 defrost control serve?

All the above

Most defrost controls used today are?

Solid state

If the heat pump is operating at its balance point?

A or B

When backup heat is needed because the heat pump is nearing the balance point we energize the second stage heat, this heat is added to the heat supplied by the heat pump; this added heat is known as?

Auxiliary

How do we size heat pumps?

Cooling load

What is the most common method of defrosting the outdoor coil of an air to air heat pump during defrost?

Hot gas from the compressor

When operating in the heating mode, hot gas leaves the compressor and first flows to?

Reversing valve

What type of metering devices are found on heat pumps?

Any of the above

What happens to the compression ratio when the heat pump is in the heating mode?

Ratio goes up

Where is the best location to place the outdoor unit of an air to air heat pump?

Where it receives winter sun

Which type of metering device can improve the operating efficiency of a heat pump?

E. EEV

Which of the following conditions can prevent a reversing valve from changing positions?

Undercharged system

Why is volumetric efficiency of the compressor important?

E. For large scale compressors that can be rebuilt

Refrigerant flow through the compressor is:

Always the same

During the heating mode, the refrigerant in the indoor coil is under:

High pressure

The true suction line is always:

Low pressure

Heat pump systems are difficult to charge properly because?

Heat pumps operate in two modes

Heat pump systems use:

The same amount

In the cooling mode the low pressure refrigerant vapor leaves the reversing valve and travels to?

The accumulator and then to the compressor

The most preferred method of charging any system in the field is?

Both C & D by weight AND superheat & subcooling

The use of a scroll compressor on a heat pump can eliminate the need for?

E. None of the above, don’t remove a safety

To determine a heat pump’s balance point, you must calculate:

Building’s heat loss

The heat pump is more efficient in what mode?

Cooling

The slide valve and piston in the reversing valve is activated by pressure directed through?

Pilot valve

Does the contactor energize on a call for heat or cool when called for by the thermostat?

Energizes for both

During a service call the fan switch position on is selected, the blower motor energizes verifying:

All the above

The customer complains there is not enough heat, service gauges are installed and pressure is higher than normal?

Check valve stuck open at outdoor coil

Pressures used in R410A heat pumps are _____ higher than R22 heat pumps?

40 to 70%

What is different about a heat pump thermostat when compared to a traditional thermostat?

Both B & C (O & B, W2 & E)

Compression ratio of a heat pump can reach ______ when in heating mode?

All the above

Pressure switches are wired in _____ with the contactor

Series

The heat pump defrost board can be manipulated by the tech to?

Simulate the defrost cycle

What temperature is an outdoor thermostat normally set to?

15 degrees above initial balance point

Describe the trickle circuit method of crank case heating

B. A small amount of current is passed through a resister, soldered to the terminals of a run capacitor to heat the start winding

When a heat pump is in the heating mode, frost can accumulate on the outdoor coil when the ambient temperature is 45 degrees Fahrenheit because?

45 degree air contains a high percentage of moisture that will freeze