Burning gas comes with some inherent safety concerns. If it is not done in a controlled environment, there is always the possibility of a fire, an explosion, or the release of carbon monoxide into the air. That’s why gas furnaces come with several safety devices that protect your home and your family if something goes wrong with your system. Today we’re going to help familiarize you with these devices by talking about five safety features that are included inside a furnace!

5 furnace safety features that protect your home from a malfunctioning system

  • Limit switch. A limit switch is located just above a furnace’s heat exchanger and just below the supply plenum. Its job is to measure the temperature outside of your furnace’s combustion chamber. If the limit switch detects flames or temperatures that are too high, that means that flames are reaching outside of the combustion chamber, which is a fire hazard. When the limit switch is activated, it immediately shuts off the gas supply to your furnace to prevent flames from spreading or carbon monoxide from getting into your home’s air. Your furnace will have to be reset by a professional before it is turned back on.
  • Thermocouple. In older furnaces with traditional pilot lights, the thermocouple is a safety device that checks whether or not the pilot light is burning properly. The thermocouple is connected to the gas valve that leads to the pilot light and has a sensor that detects heat from the burning flame. If the flame goes out or is burning weakly, the thermocouple shuts off the gas supply to the pilot light to prevent gas from leaking into other parts of your furnace.
  • Mercury flame sensor. Newer furnaces have intermittent pilot lights or electronic ignitions instead of traditional pilot lights. In these systems, a mercury flame sensor is used to perform the same job as the thermocouple.
  • Air pressure switch. Modern-day furnaces have a small fan called a draft inducer that runs after each heating cycle. This fan blows leftover gas out of the combustion chamber to clear it out before the next heating cycle. The draft inducer has a safety device called an air pressure switch that measures how much air is being blown by the inducer. If it detects that the pressure is too low, it shuts off the gas supply to the system to prevent gas from building up inside the combustion chamber.
  • Carbon monoxide detectors. Although carbon monoxide detectors are not part of your furnace, they are closely linked to your furnace’s safety because they will warn you if your system has a carbon monoxide leak. Jerry Kelly Heating & Air Conditioning offers low-level carbon monoxide detectors that can detect much lower levels of carbon monoxide than store-bought detectors, and they will warn you as CO is building up in your air instead of waiting until it’s already at a dangerous level.

If you have any questions about a furnace’s safety features, or if you’d like a heating system serviced or installed in your home, contact Jerry Kelly Heating & Air Conditioning, your St. Louis furnace installation and repair contractor. We provide service all over the St. Louis area, including towns like St. Charles, St. Peters, and Town and Country, MO.

photo credit: dab silver via photopin (license)

company icon