WorksheetsHeat pump
Total questions: 99
Worksheet time: 50mins
An air-to-air heat pump has many of the same components as an air conditioning system. The major difference is that a heat pump also has an
Reversing valve
Demand defrost happens only when needed and timed defrost is based on time/temperature.
Slightly above the initial balance point.
Initial balance point
The outdoor temperature at which the heat pump provides the same amount of heat as the heat loss of the conditioned space without an auxiliary heat is known as the;
Initial balance point
Cooling load.
As near to the main return air grill as possible.
Emergency heat mode.
What is the difference between "demand defrost" and "timed defrost"?
Demand defrost happens only when needed and timed defrost is based on time/temperature.
In a moderate climate zone.
Simply disconnect power to the unit momentarily.
Dividing the Btu's removed by the watts consumed during the cooling season.
The thermostat that controls the auxiliary electric heat according to the outdoor temperature is called the;
Outdoor ambient thermostat
Emergency heat mode.
Emergency heat mode.
Simply disconnect power to the unit momentarily.
At what temperature is an outdoor ambient thermostat normally set?
Slightly above the initial balance point.
Two outdoor coils with each one incorporating a dual stage compressor.
Emergency heat mode.
As near to the main return air grill as possible.
The outdoor coil is frozen solid on a "no heat" service call. The most likely reason is;
The outdoor fan is inoperative.
The building's heat load.
Cooling load.
Two outdoor coils with each one incorporating a dual stage compressor.
In order to determine a heat pumps' balance point, you must first calculate;
The building's heat load.
Cooling load.
Two outdoor coils with each one incorporating a dual stage compressor.
As near to the main return air grill as possible.
When a heat pump is used for heating and cooling, the system is sized by the;
Cooling load.
Two outdoor coils with each one incorporating a dual stage compressor.
As near to the main return air grill as possible.
Emergency heat mode.
A high efficiency heat pump system designed to function from high to low ambient conditions below 10*F, may have?
Two outdoor coils with each one incorporating a dual stage compressor.
As near to the main return air grill as possible.
Emergency heat mode.
Teach the customer how to program the thermostat.
Room thermostats for heat pumps should be installed;
As near to the main return air grill as possible.
Emergency heat mode.
Teach the customer how to program the thermostat.
Simulate the defrost cycle.
When the heat pump compressor has malfunctioned, the customer has the option to switch the system into;
Emergency heat mode.
Teach the customer how to program the thermostat.
Simulate the defrost cycle.
In a moderate climate zone.
Start up with a night set back digital thermostat requires the technician to always;
Teach the customer how to program the thermostat.
Simulate the defrost cycle.
In a moderate climate zone.
ECM fan motors.
The heat pump defrost board can be manipulated by the technician to;
Simulate the defrost cycle.
In a moderate climate zone.
Simply disconnect power to the unit momentarily.
ECM fan motors.
The air-to-air heat pump outdoor unit is most efficient if located;
In a moderate climate zone.
ECM fan motors.
Simply disconnect power to the unit momentarily.
Approximately 2*F
Which of the following are innovations that may be found on new high efficiency units?
ECM fan motors
Simply disconnect power to the unit momentarily.
Approximately 2*F
Dividing the Btu's removed by the watts consumed during the cooling season.
How may a lockout (impedance) relay be reset?
Simply disconnect power to the unit momentarily.
Approximately 2*F
Dividing the Btu's removed by the watts consumed during the cooling season.
The system will not properly remove the humidity from the conditioned space
The temperature difference between the 1st and 2nd bulbs for heating on a heat pump thermostat is;
Approximately 2*F
Dividing the Btu's removed by the watts consumed during the cooling season.
The system will not properly remove the humidity from the conditioned space.
By weight.
SEER is calculated by;
Dividing the Btu's removed by the watts consumed during the cooling season.
The system will not properly remove the humidity from the conditioned space.
The system will not properly remove the humidity from the conditioned space.
Maintain 500 microns for 15 minutes.
If the indoor fan is operated at an excessive speed in the cooling mode;
The system will not properly remove the humidity from the conditioned space.
By weight.
Maintain 500 microns for 15 minutes.
Maintain 500 microns for 15 minutes.
The most preferred method of charging any system in the field is;
By weight.
Maintain 500 microns for 15 minutes.
Use heat paste and wet rags while brazing in the new valve.
A small amount of current is passed through the start capacitor to start the heat winding.
What is the industry standard for deep vacuum
Maintain 500 microns for 15 minutes.
Use heat paste and wet rags while brazing in the new valve.
A small amount of current is passed through the start capacitor to start the heat winding.
Airflow in CFM is below normal range.
Good service practice for installation of a reversing valve includes;
Use heat paste and wet rags while brazing in the new valve.
A small amount of current is passed through the start capacitor to start the heat winding.
Airflow in CFM is below normal range.
The second heating stage of the indoor thermostat.
Off-cycle crankcase heat is provide by;
A small amount of current is passed through the start capacitor to start the heat winding.
Airflow in CFM is below normal range.
The second heating stage of the indoor thermostat.
A maximum of 10 minutes.
You are checking for proper airflow in CFM on a three ton heat pump system. The system has one return grill measuring 24"X24", which has a net free area of 3.4 square feet. You measure air velocity and calculate an average of 400 FPM. From this information you can conclude that;
Airflow in CFM is below normal range.
The second heating stage of the indoor thermostat.
A maximum of 10 minutes.
400 to 450 CFM
What control operates the 1st stage of secondary heat?
The second heating stage of the indoor thermostat.
A maximum of 10 minutes.
400 to 450 CFM
Use temperature rise on emergency heat mode.
What is the industry standard for maximum duration for defrost?
A maximum of 10 minutes.
400 to 450 CFM
Use temperature rise on emergency heat mode.
Time or temperature initiation, time and temperature termination.
What is the recommended CFM across the evaporator cool of a heat pump?
400 to 450 CFM
Use temperature rise on emergency heat mode.
Time or temperature initiation, time and temperature termination.
The defrost relay.
If manufacturer specifications are not available, a good way to calculate cubic feet per minute through a coil is to;
Use temperature rise on emergency heat mode.
Time or temperature initiation, time and temperature termination
The defrost relay.
The RVR coil is energized through TH-1. The CR coil is energized through the RVR contacts.
What type of defrost is employed on this heat pump?
Time or temperature initiation, time and temperature termination.
The defrost relay.
The RVR coil is energized through TH-1. The CR coil is energized through the RVR contacts.
The DFR N.O. contacts close, which forms a holding circuit.
Which component is responsible for energizing auxiliary heat during the defrost cycle?
The defrost relay.
The RVR coil is energized through TH-1. The CR coil is energized through the RVR contacts.
The DFR N.O. contacts close, which forms a holding circuit.
Either the time or temperature termination requirements has been satisfied.
When this unit switches to the heat mode, select the sequence of events which will take place.
The RVR coil is energized through TH-1. The CR coil is energized through the RVR contacts.
The DFR N.O. contacts close, which forms a holding circuit.
Either the time or temperature termination requirements has been satisfied.
On the bi-flow liquid line located between the two coils.
The DTC and cam will close the DTC N.O. contacts momentarily (approx. 5 seconds). How is the DFR kept organized when the DTC N.O. contacts open?
The DFR N.O. contacts close, which forms a holding circuit.
Either the time or temperature termination requirements has been satisfied.
On the bi-flow liquid line located between the two coils.
Increase the indoor fan speed.
How is defrost terminated in this system?
Either the time or temperature termination requirements has been satisfied.
On the bi-flow liquid line located between the two coils.
Increase the indoor fan speed.
HSPF.
Where is the LLP physically located in this system on this heat pump?
On the bi-flow liquid line located between the two coils.
Increase the indoor fan speed.
HSPF.
Direct acting.
You are starting-up a split system heat pump for the first time.the outdoor ambient temperature is 60F. You check the temperature split across the indoor coil in the heat mode and find it is 38F. You switch to cooling mode and determine a temperature split of 29*F. The most likely corrective action (relative to airflow) is;
Increase the indoor fan speed.
HSPF.
Direct acting.
4.6:1
Heat pump mode efficiency is rated in;
HSPF.
Direct acting.
4.6:1
Water source.
On a water source heat pump, the heat mode water regulating valve must be;
Direct acting.
4.6:1
Water source.
12 Degrees
An R410A heat pump operating in the heating mode has a suction pressure 50 PSIG and head pressure of 285 PSIG has a compression ratio of;
4.6:1
Water source.
12 Degrees
Every 30 or 90 minutes, depending on the cam installed in the timer.
Which type of heat pump does not require a defrost cycle?
Water source.
12 Degrees
Every 30 or 90 minutes, depending on the cam installed in the timer.
The discharge pressure and temperature will rise decreasing the life span of the unit.
An R-410A heat pump operating in the cooling mode has a suction pressure of 131 PSIG. Adding 2 PSIG for pressure drop in the coil, the true outlet pressure is 131 PSIG. The temperature of the suction line at the outlet of the evaporator is 57° F. What is the superheat?
12 Degrees
Every 30 or 90 minutes, depending on the cam installed in the timer.
The discharge pressure and temperature will rise decreasing the life span of the unit.
Cold air at high velocities coming out of the registers.
On a time initiation/temperature termination defrost, the defrost time clock has one N.O. And N.C. switch. When do the positions of these switches change?
Every 30 or 90 minutes, depending on the cam installed in the timer.
The discharge pressure and temperature will rise decreasing the life span of the unit.
Cold air at high velocities coming out of the registers.
Cold and sweaty
What would be the result of closing registers in rooms that are uninhabited while operating in the heating mode?
The discharge pressure and temperature will rise decreasing the life span of the unit.
Cold air at high velocities coming out of the registers.
Cold and sweaty
Suction line accumulator.
What is the most common complaint from a customer changing from gas heat to a heat pump?
Cold air at high velocities coming out of the registers.
Cold and sweaty
Suction line accumulator.
A stuck check valve or clogged TXV screen.
When a heat pump is operating in the heat mode, the suction line at the compressor;
Cold and sweaty
Suction line accumulator.
A stuck check valve or clogged TXV screen.
The charge is critical, sometimes to 1/2 oz. refrigerant.
The use of a scroll type compressor on a heat pump can eliminate the need for a;
Suction line accumulator.
A stuck check valve or clogged TXV screen.
The charge is critical, sometimes to 1/2 oz. refrigerant.
Reversing valve.
A heat pump operates satisfactorily in the cooling mode, but not in the heat mode. This could be caused by;
A stuck check valve or clogged TXV screen.
A stuck check valve or clogged TXV screen.
Reversing valve.
Fixed orifice.
It is not always a good idea to immediately connect a standard gauge manifold set and hoses to a heat pump when a problem is suspected because;
The charge is critical, sometimes to 1/2 oz. refrigerant.
Reversing valve.
Fixed orifice.
Solenoid and pilot valve.
Which component is responsible for changing the direction of the flow of refrigerant?
Reversing valve.
Some heat pump systems use a ______________ as a metering device.
Fixed orifice.
The slide valve and piston in the reversing valve is actuated by pressure directed through the;
Some heat pump systems use a ______________ as a metering device.
Fixed orifice.
Solenoid and pilot valve.
The evaporator.
The evaporator
The slide valve and piston in the reversing valve is actuated by pressure directed through the;
The slide valve and piston in the reversing valve is actuated by pressure directed through the;
The evaporator.
The evaporator.
Turned off.
During the heating cycle, the outdoor coil is use as;
The evaporator.
Turned off.
A by-pass lines with check valves.
is always the same regardless of operating mode.
During the cooling cycle, the indoor coil becomes;
The evaporator.
Turned off.
A by-pass lines with check valves.
is always the same regardless of operating mode.
During the defrost cycle, the outdoor fan is usually;
Turned off.
A by-pass lines with check valves.
is always the same regardless of operating mode.
Suction Accumulator.
Heat pump systems which use a thermostatic expansion valve at each coil will also have;
A by-pass lines with check valves.
is always the same regardless of operating mode.
Suction Accumulator.
is less susceptible to damage from liquid flood-back.
Refrigerant flow through the compressor;
is always the same regardless of operating mode.
Suction Accumulator.
is less susceptible to damage from liquid flood-back.
The transformer is functioning.
Because of the possibility of liquid flood-back, a heat pump that uses a reciprocating compressor should be equipped with a;
Suction Accumulator.
is less susceptible to damage from liquid flood-back.
The transformer is functioning.
The indoor and outdoor coils are the same size and physical capacity.
A scroll type compressor;
is less susceptible to damage from liquid flood-back.
The transformer is functioning.
The indoor and outdoor coils are the same size and physical capacity.
3 to 4 times more.
On a split system heat pump. A "no heat/no cooling" service call, you turn the thermostat to the fan on/ cont position and the indoor fan operates. This action verifies that;
The transformer is functioning.
The indoor and outdoor coils are the same size and physical capacity.
3 to 4 times more.
1:1
On most air-to-air heat pumps;
The indoor and outdoor coils are the same size and physical capacity.
3 to 4 times more.
1:1
Decreases.
A heat pump system, operating at 45°F ambient, may be _______ efficient than electric resistance heat
3 to 4 times more.
1:1
Decreases.
Cooling.
Since electric resistance heat produces 1 watt of usable heat for each watt of energy purchased, electric resistance heat has a COP of;
1:1
Decreases.
Cooling
High pressure.
As outdoor ambient air temperature decreases, a heat pump's COP;
Decreases.
Cooling.
High pressure.
The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized.
During the defrost cycle, the system switches to the ___________ Mode.
Cooling.
High pressure.
The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized.
Compressor inefficiency.
During the heating mode, the refrigerant in the indoor coil is under;
High pressure.
The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized.
Compressor inefficiency.
Cooling.
What three things happen in most air-to-air heat pump during defrost?
The reversing valve must switch to cooling mode, the outdoor fan shuts off and auxiliary heat is energized.
Compressor inefficiency.
Cooling.
A faulty reversing valve.
High suction pressure and low discharge pressure on a heat pump system operating in either the heating or cooling mode can be an indication of;
Compressor inefficiency.
Cooling.
A faulty reversing valve.
A stuck open check valve at the outdoor coil.
The preferred method to preform adjustments to the refirgerant charge in a heat pump system is in the ________ more.
Cooling.
A faulty reversing valve.
A stuck open check valve at the outdoor coil.
A faulty defrost relay (does not energized the aux. heat during the defrost mode.)
You answer a service call for insufficient heat. You find the suction pressure is higher and discharge pressure is lower than normal. Using a digital thermometer, you measure the line entering the reversing valve from the compressor discharge and find 215°F. You then measure the line leaving the reversing valve that connects to the indoor coil and find 185°F. These readings are an indication of;
A faulty reversing valve.
A stuck open check valve at the outdoor coil.
A faulty defrost relay (does not energized the aux. heat during the defrost mode.)
The outdoor coil is colder than the ambient air.
The customer complaint is not enough heat. You install service gauges and find the low side pressure is higher than normal and the high side pressure is lower than normal. You switch to the cooling mode and find the pressures are normal. The most likely cause of the problem is;
A stuck open check valve at the outdoor coil.
A faulty defrost relay (does not energized the aux. heat during the defrost mode.)
The outdoor coil is colder than the ambient air.
At the same speed for heating or cooling;
A customer complains that their heat pump systems blows cool air periodically during the heat mode. This could be caused by;
A faulty defrost relay (does not energized the aux. heat during the defrost mode.)
The outdoor coil is colder than the ambient air.
At the same speed for heating or cooling;
Time and temperature.
When a heat pump is in the heating mode, which can cause frost accumulation on the outdoor coil when the ambient temperature is 45*F?
The outdoor coil is colder than the ambient air.
At the same speed for heating or cooling;
Time and temperature.
Time/temperature
The indoor fan on a heat pump system operates;
At the same speed for heating or cooling;
Time and temperature.
Bleeding pressure from one side of the piston to the suction side of the compressor.
Electronic expansion valves can meter refrigerant in either direction.
The defrost cycle can be initiated by;
Time and temperature.
Bleeding pressure from one side of the piston to the suction side of the compressor.
Electronic expansion valves can meter refrigerant in either direction.
Must be a bi-flow design if used without check valves.
The defrost cycle can be terminated by;
Time/temperature
Bleeding pressure from one side of the piston to the suction side of the compressor.
Electronic expansion valves can meter refrigerant in either direction.
Must be a bi-flow design if used without check valves.
Movement of the piston in the reversing valve is accomplished by;
Bleeding pressure from one side of the piston to the suction side of the compressor.
Electronic expansion valves can meter refrigerant in either direction.
Must be a bi-flow design if used without check valves.
Defrost.
Some close coupled (package unit) heat pumps use an electronic expansion valve is;
Electronic expansion valves can meter refrigerant in either direction.
Must be a bi-flow design if used without check valves.
Defrost.
Before.
Liquid line filter-driers that are used on heat pump system;
Must be a bi-flow design if used without check valves.
Defrost.
Before.
After the heat exchanger.
When installing the heat pump outdoor unit, care should be taken to provide for drainage during the ________ cycle.
Defrost.
Before.
After the heat exchanger.
+10
The indoor coil is usually mounted in the air stream _______ the auxiliary electric heat strips.
Before.
After the heat exchanger.
+10
100
On Dual Fuel Systems, the indoor coil must be located;After the heat exchanger.
After the heat exchanger.
+10
100
Reverse cycle defrost.
Air-to-air heat pumps are most practical to operate in areas where the lowest winter temperature does not go below ______ *F
+10
100
Reverse cycle defrost.
Coefficient of performance.
Air-to-air heat pumps, operating without auxiliary heat, provide air to the registers that is approximately _______ *F or less.
100
Reverse cycle defrost.
Coefficient of performance.
Condenser to release 3 to 4 times more heat than it takes in electrical energy to drive the compressor.
The most common method of defrosting the outdoor coil on an air source heat pump is;
Reverse cycle defrost.
Coefficient of performance.
Condenser to release 3 to 4 times more heat than it takes in electrical energy to drive the compressor.
Compression.
COP is the abbreviation for;
Coefficient of performance.
Condenser to release 3 to 4 times more heat than it takes in electrical energy to drive the compressor.
Compression.
he reversing valve.
At temperatures above 45 degrees *F, the heat pump refrigeration cycle permits the;
Condenser to release 3 to 4 times more heat than it takes in electrical energy to drive the compressor.
Compression.
The reversing valve.
75 to 100 PSIG
In addition to heat from the outdoor coil, a heat pump in the heating mode will get heat from;
Compression.
The reversing valve.
75 to 100 PSIG
Verify the operating mode of the system
When operating in the cooling mode, hot gas leaves the compressor and first flows to;
The reversing valve.
75 to 100 PSIG
Verify the operating mode of the system
Low pressure/low temperature vapor.
To make the reversing valve slide move, the system must have a pressure difference of;
75 to 100 PSIG
Verify the operating mode of the system
Low pressure/low temperature vapor.
Four-way valve.
Before connecting a manifold gauge set to a heat pump system, you should first;
Verify the operating mode of the system
Low pressure/low temperature vapor.
Four-way valve.
Refrigerant will bypass the TEV on the coil serving as the condenser.
In the heat mode, the suction line entering the compressor contains;
Low pressure/low temperature vapor.
Four-way valve.
Refrigerant will bypass the TEV on the coil serving as the condenser.
By checking the temperature differential between the connection serving the low side.
The reversing valve is often referred to as a;
Four-way valve.
Refrigerant will bypass the TEV on the coil serving as the condenser.
Refrigerant will bypass the TEV on the coil serving as the condenser.
It is designed to operate at high compression ratios.
A heat pump has a thermostatic expansion valve (TEV) and a check valve at each coil. When the modes are reversed;
Refrigerant will bypass the TEV on the coil serving as the condenser.
By checking the temperature differential between the connection serving the low side.
It is designed to operate at high compression ratios.
Crankcase heater.
Mechanically troubleshooting a reversing valve can be done by;
By checking the temperature differential between the connection serving the low side.
It is designed to operate at high compression ratios.
Crankcase heater.
Heat pumps can only be charged in the cooling mode.
Compressors designed for heat pumps differ from compressors designed for A/C in that;
It is designed to operate at high compression ratios.
Crankcase heater.
Heat pumps can only be charged in the cooling mode.
Fixed orifice metering device for the heating cycle and a TXV for the cooling cycle.
One of the most important devices to insure the longevity of a heat pump's reciprocating compressor is the;
Crankcase heater.
Heat pumps can only be charged in the cooling mode
Fixed orifice metering device for the heating cycle and a TXV for the cooling cycle.
Indoor metering device is metering refrigerant and the outdoor check valve is open.
A heat pump can be difficult to charge properly because;
Heat pumps can only be charged in the cooling mode.
Fixed orifice metering device for the heating cycle and a TXV for the cooling cycle.
Indoor metering device is metering refrigerant and the outdoor check valve is open.
Accumulator and then to the compressor.
High efficient heat pump systems charged with R-410A refrigerant normally use a;
Fixed orifice metering device for the heating cycle and a TXV for the cooling cycle.
Indoor metering device is metering refrigerant and the outdoor check valve is open.
Accumulator and then to the compressor.
Heat pumps can only be charged in the cooling mode.
When a heat pump is operating in the cooling mode, the;
Indoor metering device is metering refrigerant and the outdoor check valve is open.
Accumulator and then to the compressor.
Crankcase heater.
Heat pumps can only be charged in the cooling mode.
When in the cooling mode, the low pressure refrigerant vapor leaves the reversing valve and tracked to the;
Accumulator and then to the compressor.
Heat pumps can only be charged in the cooling mode.
Four-way valve.
Low pressure/low temperature vapor.
