How Different Types of Home Heating Systems Work

Some heating systems are central systems, meaning they send heat throughout the house, usually through a series of ducts or pipes — depending on the type of distribution system. When you use a central heating system, you heat the entire house to the same temperature. 

Other options include space heating and supplemental systems. Space heating typically involves a portable electric heater, vented or vent free gas heater, or fireplace. When you use a space heater, only a small area gets heated. Some people like to use space heaters to supplement a central heating system, while others use space heaters because they only need to provide heat in a single area of their home, such as a sun room. 

A mini split system has flexibility to heat and cool and entire home or it can provide heat to a single zone or room, but it is not the same thing as a space heater. Mini split systems have a compressor located on the outside of a house that can connect to a variety of ducted, wall hung, or ceiling mounted air handling units on the inside of the house. While noisy window units have the compressor and air handler installed in each room that is heated, a mini split system locates the compressor outside of the home for quiet operation.  When you have a mini split system installed, you have the option of setting the heat to one temperature in one room and a different temperature in another area. 

How a Central Gas Heating System Works

Many people do not know how their central gas heating system works. They just expect it to keep them warm when the outdoor temperatures drop!  However, if you find yourself adding layers just to stay warm inside, it may be helpful to understand your central heating system.

Bring on the BTUs!

The Goldilocks Theory

How a Central Gas Furnace Works

1. Burning propane or natural gas generates heat in the furnace's burner.
2. The heat produced passes through a heat exchanger, making it hot.
3. Air from the home's ductwork is blown over the heat exchanger, warming the air.
4. The furnace's blower then forces the heated air into the supply ductwork, distributing it throughout the home.

Temperature Control

Draft Induced Fan

Gas Burners

Ignition switch

Heat exchanger

Draft-Induced Fan

Blower Fan

Flue

• Non-condensing furnaces - vent exhaust gases out of the home, typically through the roof.


• Condensing furnaces - uses a second heat exchanger to heat the air from condensed exhaust gases to reach higher efficiencies.


• A modulating gas furnace - continuously regulates the amount of fuel burned to maintain the set temperature of your thermostat. This modulating component can minimize indoor temperature fluctuations.

The heat capacity of a gas furnace is measured in British Thermal Units (BTUs). A BTU equals the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Ironically, the BTU is rarely used in Great Britain because it is a non-metric measurement.The higher the BTU output, the more powerful the heating system. In real world terms, the energy released by one burning match is approximately equal to one BTU.So now you understand why it requires thousands of BTUs to heat a typical home.But what is the right number of BTU's for your home?Too hot or too cold is uncomfortable! A central gas heating system should be able to provide a consistent amount of warmth to keep you comfortable inside your home. However, that means it must be sized correctly too! A “just right” size furnace can give the best balance of comfort and cost-efficiency. So it’s important that your licensed professional HVAC technician makes sure that your furnace is the right size for your space!If your furnace is sized too small, it might not be able to keep up on colder days. And typically, you want your furnace working on cold days! Depending on the indoor vs. outdoor temperature difference, an undersized furnace may fall short! Your system may have to run continuously to try to maintain the thermostat setting. This strain can cause it to become inefficient, causing increased utility bills, and result in unnecessary wear and tear on its components.If your furnace is too large for your house, it will heat your home very quickly and then shut off, or "short cycle." Repeatedly turning on and off can be hard on your furnace, potentially reducing its lifespan. For you, an oversized furnace can cause greater temperature fluctuations inside your home. An oversized central gas heating system can create bursts of warm air. This rush of heated air can trick thermostats into shutting off the system before the whole house is at temperature. This can leave you reaching for a sweater in between cycles!To make sure your central gas heating system is sized properly, contact your professional licensed HVAC technician.Simply put, a central gas heating system creates a cycle of warming cooler air. Here is the simple version:Of course, many central heating system components must work together to keep you comfortable.: The temperature control, which is regulated by the furnace control board, turns on the ignition switch and starts the heating process when the thermostat or control system calls for heat.: The draft induced fan draws air into the burner assembly. The air also allows the burners to warm the heat exchanger then is exhausted outside of the home.: When the thermostat or control system calls for heat, the gas burners valves are open to deliver gas and burn fuel.: Gas flows over the igniter to establish a flame. This flame is drawn through the burners and used to heat the heat exchanger.: The part of a gas furnace that adds heat to the indoor air. The gas combusts inside the heat exchanger, creating heat that is used to heat the passing air. The design of the heat exchanger can add energy efficient operation of a gas furnace.: Draws air into the burner assembly. The air allows the burners to warm the heat exchanger.: Uses the return venting to blow air over the hot heat exchanger. The conditioned air is then sent throughout your home via ductwork. Some furnace models offer a blower fan that can run at multiple speeds to improve efficiency.: A flue or chimney acts as an exhaust for gaseous by-products of combustion used to create heat.Gas furnaces come in a variety of shapes to fit your space. However, they can also be categorized by one of the following: