In our world right now, it is normal for us to experience different kinds of weather conditions. Some countries in the world are more prone to hot and humid days while there are other countries that are more familiar to the bitterly cold environment. Because of these varying weather conditions, human beings have to find a way to combat these extreme conditions so as to be able to remain comfortable in their own homes. And one of the ways in which they are able to do that is to have a heating, ventilation, and air conditioning (HVAC) system installed.

There are numerous types of HVAC systems, and understandably, one well-known type of HVAC system is the heating system. As the name suggests, a heating system is a mechanism for maintaining temperatures at an acceptable level by using thermal energy within a home, office, or other dwellings. The heating system is the HVAC system that is primarily used by people who reside in primarily cold areas. And just like any kind of electrical appliance out there, the heating system is a complex piece of machinery. In order to be able to provide the best heating systems and other related services to your customers, you, as an HVAC professional, must first know everything you can about heating systems. This means that you need to know the primary components of a heating system as well as its various different kinds.

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What Comprises a Heating System?

Despite the complex design of a heating system, it can actually be broken down into three key parts. These three key parts are as follows:

The Heat Source

The heat source of any heating system is usually a furnace or a heat pump. The furnace is a large component of a heating system, requiring substantial space — which is why it is usually located in the cellar, basement, attic, or a special closet designed for furnaces specifically. The primary function of a furnace is to heat a supply of air, which is to be distributed to various rooms of the house via the system. This heating process can be accomplished through combustion (burning natural gas, oil, coal, or propane), electrical resistance, heat pump, or solar energy collected on site.

Meanwhile, a heat pump is just a two-way air conditioner. For heating systems, in particular, heat pumps operate by pulling heat out of the air or ground and use it to warm the building.

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Air Circulation System

The air circulation system primarily refers to the duct-work, which is the extensive network of large pipes that carries heated air to and from various locations of the building. The warm air is forced through the supply ducts by blower fans that are strong enough to send the heated air to the farthest point of the duct network. There, it then exits the building through vents or registers. After that, air comes back to the heating system through return ducts that bring cool air to the furnace to be heated and circulated again. Ducts are commonly made of lightweight aluminum. But sometimes, they can also be manufactured using steel, flexible plastic, polyurethane, fiberglass, or fabric.

In addition to duct-work, the air circulation system also includes vents. Vents are the rectangular outlets that transfer the heated or cooled air from the duct system and into the individual rooms of the building. These are made of high- and low-temperature safe material, and they are located on or near the ceiling and are usually fronted with angled slats. These angled slats direct the treated air downward to where people are using the room. Sometimes, vents are manually controlled or even closed, in order to control the amount of heating or cooling that a particular area receives.

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The thermostat is the component that senses the temperature of a physical system and performs actions so that the system’s temperature is maintained near a desired set-point. In other words, it is the device that is responsible for controlling when the heat source turns off or on. When the temperature inside the building falls below the desired level, the thermostat will send a signal that activates the heat source.

Most thermostats are either older-style units with a mercury switch and metallic internal thermometers or newer programmable digital models. The programmable thermostats give people much better control over when and how long the building’s heating system operates. Additionally, smart thermostats have also slowly risen to prominence as of right now. This kind of thermostat has the same features as a programmable thermostat, but it also has added features, such as Wi-Fi connectivity.

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What Are the Types of Heating Systems?

Since the concept of a heating system has been around for some time now, it is understandable that there are currently quite a number of different kinds of heating systems. The following are some of the most popular ones that are in use today.


The furnace is a type of heating system that is sometimes referred to as a ducted warm-air or forced warm-air distribution system. It works by blowing heated air through ducts that deliver the warm air to rooms throughout the building via air registers or grills. This particular kind of heating system can be powered by electricity, natural gas, or fuel oil.

Inside a gas- or oil-fired furnace, the fuel is mixed with air and burned. The flames heat a metal heat exchanger where the heat is transferred to the air. Air is then pushed through the heat exchanger by the air handler’s furnace fan and then forced through the ductwork downstream of the heat exchanger. Then at the furnace, combustion products are vented out of the building through a flue pipe.

Older “atmospheric” furnaces vented directly to the atmosphere, thus wasting about 30% of the fuel energy just to keep the exhaust hot enough to safely rise through the chimney. Current minimum-efficiency furnaces reduce this waste substantially by using an “inducer” fan to pull the exhaust gases through the heat exchanger and induce a draft in the chimney. Meanwhile, condensing furnaces are designed to reclaim much of this escaping heat by cooling exhaust gases well below 140°F, where water vapor in the exhaust condenses into water. This kind of furnace typically vents through a sidewall with a plastic pipe.


Boilers are special-purpose water heaters. While furnaces carry heat in warm air, boiler systems distribute the heat in hot water, which gives up heat as it passes through radiators or other devices in rooms throughout the building. The cooler water then returns to the boiler to be reheated. Hot water systems are usually called hydronic systems, and residential boilers typically use natural gas or heating oil for fuel.

Instead of a fan and duct system, a boiler uses a pump to circulate hot water through pipes to radiators. Important boiler controls include thermostats, aquastats, and valves that regulate circulation and water temperature. Some controls are standard features in new boilers while others can be added on to save energy.

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Heat Pumps

As was mentioned earlier, heat pumps are two-way air conditioners. During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outdoors. During the winter, the heat pump reverses this process, scavenging heat from the cold outdoors with the help of an electrical system and discharging that heat inside the house.

There are two relatively common types of heat pumps. The first type is the air-source heat pump, which uses the outside air as the heat source in winter and heat sink in summer. The second type is the ground-source heat pump, which gets its heat from underground — where temperatures are more constant year-round. Between the two, air-source heat pumps are far more common because they are cheaper and easier to install. However, ground-source heat pumps are much more efficient and are frequently chosen by consumers who plan to remain in the same house for a long time or have a strong desire to live more sustainable.

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Gas-Fired Space Heaters 

A gas-fired direct heating system includes wall-mounted, free-standing, and floor furnaces, all characterized by the lack of duct-work and relatively small heat output. Because the system lacks ducts, it is most useful for warming a single room. If heating several rooms is required, either the doors between the rooms must be left open or another heating method is necessary. Additionally, because of the fact that gas-fired space heaters don’t have exhaust vents, using them is discouraged, primarily for health and safety reasons.

Electric Space Heaters

Portable (plug-in) electric heaters are inexpensive to buy but are costly to use. This kind of heating system includes “oil-filled” and “quartz-infrared” heaters, and the way it operates is by converting electric current from the wall socket directly into heat, like a toaster or clothes iron. Electric space heaters take a lot of electricity to deliver the same amount of useful heat that natural gas or oil can provide onsite. But despite that, they are actually the least bad solution when it comes to intermittent use since alternatives would require major investments to improve duct-work for a specific area.

Wood-Burning and Pellet Stoves

Wood heating can make a great deal of sense in rural areas for those people who enjoy stacking wood and stoking the stove or furnace. Wood prices are generally lower than gas, oil, or electricity. And the savings are even larger if the person cuts their own wood. That said, wood-burning produces pollutants, which are harmful to the environment, and so new models are clean-burning. In particular, pellet stoves are more advantageous in that they are less polluting than wood stoves and offer users greater convenience, temperature control, and indoor air quality.


Gas and most wood fireplaces are basically part of a room’s decor, providing a warm glow but not really an effective heat source. With customary installations that rely on air drawn from the room into the fireplace for combustion and dilution, the fireplace will generally lose more heat than it provides because so much warm air is drawn through the unit and must be replaced by cold outside air. On the other hand, if the fireplace is provided with a tight-sealing glass door, a source of outside air, and a good chimney damper, it can provide useful heat.


Heating systems are incredibly important for a lot of people. This is because there are some places in the world that gets unbearably cold during certain times of the day or seasons of the year, and so, people would naturally want to combat these extremely cold conditions. And that is your primary job as an HVAC professional: to provide heating systems and heating solutions to your customers.

However, before you could serve your customers, you must first have to know all about the necessary components of a heating system as well as the different kinds of heating systems. This is the information that you have found in this post. By knowing about the important components of a heating system and its various different types, you will understand better how the system actually works. And that, in turn, will help you be able to provide the best products and services to your customers.



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