• SkillCat Team

Introduction to Heating in HVAC

Heating Systems: Chapter 1


In this module, we will give a brief overview of heating systems and their components. We will also explore how heat is generated and distributed in heating systems.

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1. Overview


Heating systems have a simple purpose: to ensure our comfort. Heating systems raise the temperature of cold spaces to keep us warm and cozy! Fireplaces are some of the oldest and most simple heating systems.


The main components of any modern heating system in HVAC are:

  • Thermostat,

  • Heat source,

  • Burner system,

  • Heat exchanger, and

  • Heat distribution system

We will now define each of these components!


Thermostats control the temperature of your home. Think of the thermostat as your TV remote. When you want to change channels, you press a button on your remote. When you want to change the temperature of your home, you press a button on your thermostat!


In order to increase the temperature of your home, you also need a source of heat. The heat source, or fuel, can be a substance like natural gas, oil, or firewood. We mix this heat source with oxygen in the burner system.


In the burner system, we apply a spark of heat to this fuel-oxygen mixture, starting combustion. Recall that combustion is the process of burning and requires fuel, air, and heat. Combustion in the burner system creates the heat we use to heat our homes!


Once we have created heat in the burner system, we must transfer this heat to the air or water in our homes. The heat exchanger is the component that makes this possible. Heat exchangers move heat from the burning fuel to the air or water that we want to be heated.


So far, we combusted a heat source in the burner to create heat. Then we transferred this heat to the air using the heat exchanger. And, finally, we need a way to distribute this hot air to our rooms. This is where the distribution system comes in!


In heating systems, the distribution system provides a path for heat to enter each room inside your home. When we distribute air, we use ductwork. When we distribute water, we use pipes. Ductwork and pipes provide a path for heat to enter your room and keep you warm!


Let’s talk about the difference between creating heat and distributing heat. Heat creation is the process of making heat. Heat distribution is the process of moving this heat where we want it.


Think of agriculture — we create food on farms, but then we distribute it to grocery stores so we can access it. The same is true of heat creation and distribution. Heat is created in the burner system, but we use ductwork and pipes to distribute it to our rooms!


2. Generating Heat


Gas is one of the most common fuels used by heating systems. Gas heating systems rely on combustion to produce the heat that warms our homes. Modern gas heating systems burn fossil fuels like natural gas, propane, and butane.


Oil heating systems also rely on combustion. Burning oil generates heat we can use to heat air or water in our homes.


We can also use electricity to heat our homes. Your oven is an example of an electric heater! We pass electricity through its coils, generating heat. Instead of using this heat to warm our homes, we use it to cook food.


Gas and oil heaters both rely on combustion but use different fuels. Electric heaters create heat with electricity instead of burning fuels. All heaters rely on the natural flow of heat from hot to cold spaces. They create heat, and it flows to a cooler place that we want heated.


3. Distributing Heat


Recall that heat transfer is the movement of heat from one place to another.

We can transfer heat using three methods:

  • Conduction,

  • Convection, and

  • Radiation.


We primarily rely on convection to distribute heat in our homes. Recall that convection causes hot air to rise and cool air to fall. We make use of this by placing heaters below areas we want heated, so that heat rises into them naturally.


Convection causes hot air created by the heating system to rise into our homes. This hot air transfers its heat to the air in our homes, warming us up. After it transfers its heat, the air cools down and settles. It is then heated again by the heating system and the cycle repeats!


4. Furnaces and Boilers


Recall that a furnace is a heating unit that uses combustion to heat entire homes or buildings. Furnaces provide warmth by sending hot air, steam, or water to different spaces that we want to be heated. Furnaces are the most popular way to heat homes in the United States!


Furnaces mix fuel with air in the burner system to start combustion. This heats up the heat exchanger, which then transfers heat to the air. Because of convection, this hot air naturally rises through ductwork and into our rooms.


Furnaces that heat water instead of air are called boilers. Instead of exchanging heat with air, the heat exchangers in boilers heat water. You can use this hot water in your home for showers, cooking, and other day-to-day tasks!


Boilers use the same method of heat creation as furnaces. However, instead of ductwork, they rely on pipes for heat distribution. Pipes are sturdier than ductwork, so they are better suited for transferring water, which is heavier than air.


Boilers also rely on pumps. This is because, unlike air, water does not rise naturally through convection. Pumps use electricity to force water up through the boiler and into radiators in our rooms.


This hot water heats the radiator. Cool air in our rooms flows over the warm radiator, absorbing its heat. This heated air keeps us warm and cozy! We place radiators on the floor so that convection naturally distributes their heat throughout our rooms.


We use furnaces to heat air, and boilers to heat water. Both create heat in the same way. They use burners to mix fuel with oxygen, starting combustion and creating heat. They then transfer this heat to air or water using heat exchangers.


Furnaces and boilers have different heat distribution systems. In furnaces, convection causes hot air to rise directly into our homes through ductwork. Boilers use pipes and pumps to force heated water up into radiators, which heat our rooms using convection.



5. Conclusion


Gas and oil heaters combust fuels to create heat, while electric heaters rely on electricity. Furnaces and boilers both use burners to create heat. However, they distribute this heat differently — furnaces use ductwork, while boilers use pipes and pumps.


Question #1: We mix the __________ with oxygen in the burner system.

  1. Heat source

  2. Thermostat

  3. Heat exchanger

  4. None of the above

Scroll down for the answer...















Answer: Heat source

We mix the heat source with oxygen in the burner system.


Question #2: In the burner system, combustion occurs and ________ the heat we use to warm our homes.

  1. Distributes

  2. Extinguishes

  3. Creates

  4. Removes

Scroll down for the answer...

















Answer: Creates

An HVAC installer should be physically strong, able to read blueprints, and have great time management.


Question #3: The ____________ transfers heat created by the burner to the air, then the distribution system carries this hot air to our rooms.

  1. Fuel

  2. Thermostat

  3. Heat exchanger

  4. Ductwork

Scroll down for the answer...















Answer: Heat exchanger

Fuel mixes with air in the burner, creating heat. The heat exchanger transfers this heat to the air. The distribution system carries this hot air to our rooms.


Question #4: Heat distribution is the process of making heat, and heat creation moves this hot air where want it.

  1. True

  2. False

Scroll down for the answer...















Answer: False

Heat creation is the process of making heat. Heat distribution is the process of moving this heat where we want it. The question statement is false.


Question #5: While gas and oil heaters combust fuels to create heat, electric heaters rely on electricity.

  1. True

  2. False

Scroll down for the answer...









Answer: True

Oil and gas heating systems burn fuels to create heat, while electric heaters use electricity. This statement is true.


Question #6: We make use of convection by placing heating systems above the areas we want heated.

  1. True

  2. False

Scroll down for the answer...















Answer: False

Convection causes hot air to rise and cool air to fall. We make use of this by placing heaters below areas we want heated, so that heat rises into them naturally.


Question #7: Furnaces transfer heat through the air using ductwork, while burners transfer heat through water using pipes and pumps.

  1. True

  2. False

Scroll down for the answer...











Answer: True

We use furnaces to heat our air and boilers to heat our water. Furnaces and boilers also have different heat distribution systems — furnaces use ductwork, while boilers use pipes and pumps.

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