Heating and Air Conditioning

Get to Know your Central Heating System


As the temperatures begin to fall, you’ll soon be turning on your heating system in order to heat your home. Although you are grateful for the warmth it brings on chilly days, do you know how your heating system works? If you’re like most homeowners, you probably don’t! This article is going to go over four main types of central heating systems and how they work. Find yours below, and learn how it works, and what maintenance you should be doing to keep it running longer. Before we begin, it’s important to note that these four systems are not the only ways to heat your home, nor are all of them covered under a Landmark Home Warranty. (Landmark does not cover for oil furnaces.) However, these are some of the most popular (and common) central heating systems.

What is a Central Heating System?

A central heating (or cooling) system is an air conditioner and/or furnace that is connected to each room of the home through a series of ducts and registers (the grates on the ceiling or floor of your home). The ducts take the warm air in the winter from the furnace or heat pump and blow it through the ducts and out the registers, using that air to warm your home.

A space heater, window air conditioner, or even an evaporative cooler (swamp cooler) are not central heating or cooling systems because they are generally in one part of the home and, when you turn them on, they don’t heat or cool the entire home. They only heat or cool the portion of the home where they are located.

Every central heating system has the same four things in common:

      • A thermostat
      • A way to heat the air
      • A blower fan to blow the air into your home
        • Ductwork so the air can travel to each room

        The thermostat is constantly monitoring the air in your home. When it drops below the temperature you have set, the computer inside it will turn on your central heating system to get things warm.

        When the thermostat turns on the heating system, the furnace will begin heating the air. A blower fan will blow this warm air to each room of your home through the ductwork.

        Overall Maintenance for Central Heating Systems

            • Before you turn on your furnace for the season, make sure to clean and dust it. This will help air flow more freely through the unit.
            • Change your air filter every 1-3 months throughout the season.
            • Get a furnace tune-up in the fall.

        Different types of central heating systems heat up the air in different ways. Let’s take a look:

        Forced-Air Gas Furnace

        The forced-air gas furnace relies on the burning of natural gas to warm the home. A gas furnace has a pilot light that should always be burning.

        When the air drops to a certain temperature, the gas furnace will use the pilot light to turn on the gas burners. These burners will ignite and burn natural gas. A draft motor will begin to take air into the unit and the air from the draft motor is taken into the furnace. This combination of burning gas and air moves into the heat exchangers of the furnace. It’s vented outside of the home.

        Click to download central heating system information.

        As this warm air and gas flow through them, these heat exchangers will get very warm. As they heat up, a blower motor brings cool air from around the furnace or from the return vent and blows it past the heat exchangers. The air will heat up and will be blown throughout your home.

        Click to download central heating system information.

        As it cools down, it will come back into the furnace to start the process over again.

        Maintenance Tips for Forced Air Gas Furnace

        Click to download central heating system information.
          • Make sure there is no black soot around the burner or furnace. If you see black soot, it could mean that your burners are not functioning properly and are burning more than gas. You will want to call a technician to look at this.
          • Make sure that your pilot light is a blue flame instead of a yellow flame. Yellow flames mean that something other than natural gas is burning.
          • You should also check your fan belt before turning the unit on. If it shows sign of cracks or fraying, you’ll need to replace it.
          • Make sure you get a furnace tune-up from your home warranty company before you turn on your gas furnace for the cooler weather.
            • Forced-Air Electrical Furnace

              How a forced air furnace works.

              Click to download central heating system information.

              Unlike the furnace above, an electrical furnace does not burn fuel to heat the air in your home. Instead, a forced air electrical furnace replaces the heat exchangers in the furnace for a number of heated coils.

              How a forced air electrical furnace works.

              Click to download central heating system information.

              When the temperature drops in your home, the thermostat will send a signal to the furnace, which will turn on these electric elements. The electric elements inside of the furnace will heat up and a blower fan will blow cool air over them, warming the air and bringing it throughout your home.

              How a forced air electrical furnace works on the outside.

              Click to download central heating system information.

              The electric furnace is a greener option for a homeowner and may reduce utility costs in your home.

              Maintenance tips for Electric Forced Air Furnace

              How to maintain your electrical forced air furnace.></a>
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              Click to download central heating system information.

              Besides the tips listed above you should:

        • Check the wiring before you turn on your furnace to ensure they have not frayed.
        • Check the belt on your fan for cracks or fraying. If there are any problems, you may need to replace it.
        • Remember to get a furnace tune-up before you turn on your electric forced-air furnace for the winter season!


        Air-Source Heat Pumps

        Diagram of an air source heat pump.></a>
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        Click to download central heating system information.

        The air-source heat pump is quite different than most of these furnaces. Instead of burning fuel, a heat pump simply transfers heat from the air around your home instead of creating it. In fact, it can reduce the amount of electricity you use for heating purposes by 40%. At its core functionality, it works more like a refrigerator than the furnaces above. That’s because it uses refrigerant as the way to heat the home.

        If that’s confusing, it’s okay. To truly understand how a heat pump works, you have to understand some basic principles of refrigerant.

        Refrigerant is a gas when heated and a liquid when cooled, much like water. Unlike water, though, it has a much lower boiling point, which means it doesn’t require much heat to heat it up and turn it into a gas. Another important thing to remember is that the more pressure the refrigerant has on it, the lower the amount of heat it will need to boil.

        When the temperature in your home dips, your thermostat will send a signal to your heat pump to begin heating the home.


        The heat pump begins moving the cooled liquid refrigerant outside of the home into a condenser, which puts the liquid into a pressurized line. This pressurized line makes it so the liquid can begin boiling at a much lower temperature than water. The liquid refrigerant will begin to boil from the ambient air around your home and turn into a warm gas. Yes, even the cool air outside of your home on those chilly nights has some heat in it, and that heat makes the refrigerant turn into a gas.



        As the hot gas moves through the condenser, it goes inside of the home. A blower fan blows cool air from your home over the top of the coils that contain hot gaseous refrigerant. The refrigerant transfers the heat into the air, warming the air. The warm air is blown throughout your home.


        The refrigerant returns to the outside portion of the heat pump and moves through a valve into a less pressurized line. It cools down and becomes liquid again. It moves back into the compressor to start the process over again.

        Maintenance Tips for Heat Pumps


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        Click to download central heating system information.

        Besides the overall maintenance tips at the beginning of this article, you should do these things to maintain your heat pump and keep it running for a long time.

        • Make sure that you change your filters once a month. With a heat pump, this is especially important.
        • You should also check your drain pans for moisture every month. If you see excessive moisture, call a qualified technician. They can help you determine if you need to clean the condensate drain.
        • Don’t let snow or ice build up on the heat pump during the winter.

        Forced-Air Oil Furnace

        A forced-air oil furnace works in a similar way as a forced-air gas furnace. However, instead of natural gas or propane, a forced-air oil furnace burns oil. Just a reminder: Landmark Home Warranty doesn't cover oil furnaces in any home warranty plan.

        Click to download central heating system information.

        Your furnace will have an oil tank and when it’s time to start the furnace, oil from the oil tank will move to the combustion chamber, mix with air, become a mist, and ignite. This heats up the heat exchangers and the system works in the same manner as the forced air gas furnace above.

        Click to download central heating system information.

        Maintenance Tips for a Forced-Air Oil Furnace:

        Click to download central heating system information.

        As well as the maintenance tips mentioned above, you should continually check on your furnace throughout the season.

        Remember: Landmark Home Warranty does NOT cover oil furnaces! 

        There you have it! Four popular central heating systems explained. If you have a Landmark Home Warranty, you’re in luck! Your gas, electrical or heat pump furnace is covered! If you don’t have a home warranty to repair or replace your failed furnace yet, don’t worry. You can get one today! Get a free quote for your home, and determine which plan is best for you. Then, revel in being protected by the best.


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