Basic Electrical Systems and Controls: Chapter 1
Electric Components - Part 1
In this module, we will take a look at the electrical components of standard HVAC systems. We will also discuss how they operate. Skip to quiz!
Overview
There are four basic properties of electricity:
Voltage (V),
Current (I),
Resistance (R), and
Power (P)
We will go over each property and see how they relate to one another.
Recall that voltage is a measure of the electrical potential between two points. Voltage has the symbol “V”. We can think of voltage as we would think of the height of a waterfall. The higher the waterfall, the higher potential the water will have when it reaches the bottom.
Recall that current is the rate at which the electrons flow. Current has the symbol “I”. Think back to our waterfall example. Here, current can be related to the amount of water passing through a given point in the waterfall. Electrons are represented by water.
Resistance is a measure of opposition to current flow. Resistance has the symbol “R”. In our waterfall example, we think of opposition to the flow of water. The resistance in the waterfall is the jagged path of the river.
Power is a property we can calculate from the other properties. Power has the symbol “P”. Power is equal to current times voltage (P = I*V).
Recall that HVAC systems provide heating and cooling. HVAC systems take clean air from the outdoors and provide either hot or cold air indoors. These systems achieve this by operating off electricity.
The electrical components of standard HVAC systems can be categorized into:
Control Components,
Safety Components,
Primary Components, and
High Load Components
We will study what these components are used for and how they use electricity to operate.
Control components are used to regulate the operations of heating, ventilation, and air conditioning equipment. A thermostat is an example of a control component. Decreasing the thermostat will control the air conditioner.
Safety components are the components put in place to protect both us and other electrical equipment. An example of a safety component is a fuse. If the current in our circuit is too high, the fuse will melt, and the circuit will break.
Primary components are the electrical components that are common to all circuits. An example of a primary component is a resistor.
High load components are those that consume large amounts of power. Motors are categorized as high load components. The evaporator has a fan motor that runs off of electricity.
Evaporator Components
Recall that the purpose of cooling appliances is to provide cold air or water. The evaporator makes this possible by absorbing surrounding heat and transferring it to the refrigerant.
The evaporator has only one component that requires electricity to operate: the evaporator fan motor. Recall that a motor is a device that uses electricity to rotate. We also call it a “blower motor”.
The evaporator fan, or blower fan, is connected to the evaporator fan motor. When the evaporator fan motor is powered by electricity, it will rotate the fan. The rotating fan will circulate air through the evaporator coils.
The evaporator coils are used to cool the air. These coils absorb the heat from the air that passes over them and transfers the heat to the refrigerant.
Recall that the evaporator fan motor is the only component that requires electricity. The fan motor is a high load component. Electricity will cause the fan motor to rotate, and the fan will pass air through the system. This air will cool as it passes through the evaporator coils, and the heat is transferred to the refrigerant.
Compressor Components
A compressor is essential to the refrigeration cycle. A compressor is a piece of equipment used to increase the pressure of refrigerant vapors.
The compressor sucks in low-pressure refrigerant vapor and compresses it to a higher pressure. The increase in pressure will increase the temperature of the refrigerant vapor.
The compressor has two components that run off of electricity:
Compressor Motor, and
Solenoid Valve
We will see how electricity affects these components and allows for the compressor to perform its task.
The compressor changes the low-pressure refrigerant to a high-pressure refrigerant with the help of the motor. Recall that a motor uses electricity to rotate.
The rotation of the motor allows the compressor to squeeze the refrigerant. By squeezing the refrigerant, the refrigerant increases in both pressure and temperature. Refrigerant is sent to the compressor from the solenoid valve.
A solenoid valve is a type of valve that uses electrical signals to operate. Recall that a valve is used to control the flow of air or liquid through a pipe. The solenoid valve is used to control the flow of the refrigerant.
The solenoid valve opens and closes depending on the electrical signal it receives. These electrical signals allow the valve to control both the flow and the amount of refrigerant in the compressor.
By using electricity, the compressor controls the flow of refrigerant with a solenoid valve and squeezes it with a motor. Squeezing allows the compressor to perform the primary function of raising the temperature and the pressure of the refrigerant.
The four main properties of electricity are voltage, current, resistance, and power. Electricity is essential in HVAC systems to achieve the process of heating and cooling.
The evaporator is used to deliver cool air indoors. The compressor is used to compress the refrigerant to a higher temperature and pressure. These key components will not function without electricity.
Electric Components - Part 2
In this module, we will continue introducing you to the electrical components of standard HVAC systems. We will also discuss how they operate. Skip to quiz!
Condenser
A condenser is used to exchange heat with the outside air. This exchange of heat is used to cool the refrigerant and release the heat outdoors.
The exchange of heat between the air and the refrigerant is the opposite process as the evaporator. Recall that the evaporator cools the air by using the refrigerant to absorb its heat. The condenser cools the refrigerant and gives off its heat to the air.
The condenser has only one component that requires electricity to operate: the condenser fan motor. Recall that a motor is a device that uses electricity to rotate.
The condenser fan is connected to the condenser fan motor. When the condenser fan motor is powered by electricity, the condenser fan will send air through the condenser coils.
The condenser coils are used to heat the air and cool the refrigerant. Air from the condenser fan will pass through these coils and eventually send the heated air outdoors.
Recall that the condenser fan motor is the only component that requires electricity. Electricity will cause the fan motor to rotate and circulate air. The air will travel over the coils where the refrigerant will be cooled, and the exchanged heat will pass outdoors.
Metering Device
A metering device is a component used to control the flow of refrigerant going into the evaporator coils. The refrigerant is supplied by the condenser coils.
Recall that the refrigerant from the condenser coils is high-temperature and high-pressure. The metering device ensures that the refrigerant is at low temperature and low pressure once it reaches the evaporator coils. The solenoid valve controls the flow of the refrigerant in the metering device.
The metering device has only one component that requires electricity to operate: the solenoid valve. Recall that a valve is used to control the flow of air or liquid through a pipe.
A solenoid valve opens and closes depending on the electrical signal it receives.These signals allow the valve to control the flow of refrigerant from the condenser coils to the evaporator coils.
Heating Systems
We have studied the electrical components in the cooling process. We will now look at electrical components in the heating process. The primary heater in typical HVAC heating systems is a gas heater. If there is a problem with the gas heater, such as running out of gas, we will rely on a backup system.
The following components will require electricity to function:
Thermostats,
Control Board,
Fan Control Unit,
Indoor Blower Fan Relay,
Indoor Blower Motor, and
Compressor Fan Motor.
We have already seen how fan motors use electricity.
We will address the other components in a different module. Let’s focus on the backup heating system: the electrical heater. We will see how electricity is used to generate heat.
The electric heater consists of a heating element with a high electrical resistance. Recall that electrical resistance is a measure of opposition to current flow. The higher the resistance, the higher the element can heat without melting.
As electricity is passed through the heating element, it will oppose the flow of current. The opposition of current flow will generate heat. The heat will pass into the room and accomplish the task of the heating system.
Ventilation Systems
Recall that ventilation systems are designed to move contaminated air outdoors and bring in clean air indoors. The ventilation system consists of a series of pipes that air moves through and vents for air to escape.
The ventilation system has only one component that requires electricity to operate: the fan motor. Recall that a motor uses electricity to generate rotation.
To move air throughout the ventilation system, we need the help of fans. Ventilation fans are connected to the fan motors.
When electricity is supplied, the fan motor will rotate the fan and send air throughout the ventilation system. These fans must have enough speed to capture contaminants and pass them through the vent system. The contaminants are passed through the air filters, and into the outdoors.
The condenser is used to deliver hot air outdoors. By using electricity, the condenser fan motor rotates, and hot air circulates over the condenser coils and moves outside.
Metering devices, heating systems, and ventilation systems rely on electricity to function. Electricity is used in these components to operate valves, generate heat, and power motors.
Question #1: Which of the following is not one of the four basic properties of electricity?
Voltage
Resistance
Current
Magnetism
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Answer: Magnetism
The four basic properties of electricity are voltage, current, resistance, and power.
Question #2: Which of the following is not a category of electrical components?
Secondary Components
High Load Components
Safety Components
Control Components
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Answer: Secondary Components
Electrical components can be categorized into control components, safety components, primary components, and high load components.
Question #3: Safety components are components put in place to protect both us and other electrical equipment.
True
False
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Answer: True
Safety components are components put in place to protect both us and other electrical equipment.
Question #4: The evaporator fan is the only component of the evaporator that requires electricity.
True
False
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Answer: False
False, the evaporator fan motor is the only component of the evaporator that requires electricity.
Question #5: How many components in the compressor run off of electricity?
1
2
3
4
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Answer: 2
The compressor has two components that run off of electricity: The compressor motor and the solenoid valve.
Question #6: The solenoid valve uses electricity to control the flow of the refrigerant.
True
False
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Answer: True
True, the solenoid valve uses electricity to control the flow of the refrigerant.
Question #7: The condenser is used to cool the refrigerant and pass the exchanged heat outdoors.
True
False
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Answer: True
True, the condenser is used to cool the refrigerant and pass the exchanged heat outdoors.
Question #8: The refrigerant that comes from the condenser is low temperature and low pressure.
True
False
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Answer: False
The refrigerant that comes from the condenser is high temperature and high pressure.
Question #9: The primary heater in typical HVAC heating systems is a gas heater.
True
False
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Answer: True
The primary heater in typical HVAC heating systems is a gas heater.
Question #10: Which of the following is not a part of the ventilation system?
Coils
Ventilation fans
Air pipes
Air vents
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Answer: Coils
Coils are not a part of the ventilation system.