How Do Gas Furnaces Work?

How Do Gas Furnaces Work?

Gas furnaces heat your home through a process of several steps.

As the outside grows colder in the deep of winter, it can be helpful to know how your main source of heating for your abode runs. Should something go wrong, you may either be able to troubleshoot the problem yourself, or know that a professional repair is at hand. While furnaces run on different power sources, like propane, electricity, or solar power, gas furnaces are more common nationwide and in Maryland. Therefore, below is a brief look at how gas furnaces work.

Thermostat Control

The workings of the furnace begin with the thermostat. A thermostat will rest at a certain temperature, and every time the air in the house falls below this number of degrees, it will send a command to the furnace to turn on for a set time. When the furnace receives this signal, the gas valve will open and send the natural gas to the appliance’s burners. The pilot light’s monitor is the thermocouple, which makes sure that the pilot light is working before gas enters the furnace.

Heating Up

When the burners generate heat from the gas, they send that heat through the heat exchanger. The heat exchanger is a bundle of looping tubes that transform heat into air. Without a working heat exchanger, your home will receive no heat. The most efficient types of furnaces use nearly all the warm air they produce for the home, while a small percentage is lost. The measurement of how efficiently your furnace uses fuel is its AFUE or Annual Fuel Utilization Efficiency. A top-of-the-line furnace will utilize 98%, while one of lower quality will take up 50 to 70%.


Next, the furnace has a fan which blows the warm air from its chamber through the ducts of the home. While the fan takes air into the home, a flue takes the noxious fumes produced by the burners out of it. These fumes contain carbon monoxide, which are deadly. If there is any crack in that pipe, you will need to call for an emergency service. Make sure to quickly catch and prevent this problem by installing carbon monoxide sensors with new batteries, plus having regular furnace inspections. 


If you are concerned about high electricity bills in the winter, consider investing in geothermal heat pumps to help alleviate some of those costs. With many experienced technicians available, Ground Loop Heating & Air Conditioning, Inc. can solve all your air conditioning system problems. If you are interested in creating the most comfortable environment for your family to enjoy, contact Ground Loop Heating & Air Conditioning,

You can reach us at 410-836-1706, or visit our website for more information! If you are interested in more information about geothermal heating and cooling systems, check us out on Twitter, YouTube, Facebook, and LinkedIn.

This entry was posted on Thursday, January 9th, 2020 at 12:13 pm. Both comments and pings are currently closed.

Comments are closed.

Contact Us