Your fuel-burning furnace has a number of mechanisms allowing it to run safely and effectively. These features prevent fires and protect your indoor air quality (IAQ). They also work to prevent internal errors from damaging large portions of your furnace.
1. Air Filters
This component protects your furnace’s internal parts and your indoor air quality. Air filters catch dust and debris, which would otherwise be circulated by your air ducts. Not only does dust make you sneezy, it can actually hurt some of the mechanical parts in your system over time. Remember to change your filter before it gets clogged, or else you’ll end up with a variety of problems due to poor airflow. Check your manufacturer’s recommendations to see how frequently you need to change it, though we typically recommend every month or at least every couple.
These are sensors protecting you from gas leaks. If your pilot light won’t turn on, the valve is leaking gas into your home. Thermocouples use thermal imagery to detect a flame source. When the thermocouple doesn’t sense your pilot light, it will automatically shut down your furnace to prevent the harmful fumes from circulating.
3. Pressure Switches
These switches detect changes in pressure that could indicate an error in your heating system. One such error is called backdrafting. Backdrafting is when exhaust is reintegrated into your furnace instead of exiting through the flue. This can be potentially deadly to breathe and is indicatory of other problems within the system.
4. Rollout Switches
Rollout is when the burner flames become too hot, or too high, leading to fire hazards. This is often a symptom of a cracked heat exchanger. Rollout switches sit near the burners and shut the furnace off if things get too hot. This prevents a fire, as well as carbon monoxide (CO) production due to combustion.
5. Limit Switches
Limit switches “limit” the overall temperature of your furnace to keep it from overheating. Your heating system will a factory-designed switch to meet specifications for your particular make and model. Once the switch detects the temperature to be past a set peak (for example 200 degrees Fahrenheit), it will cut off the power to your system.
Your furnace flue is a pipe sending exhaust out of your home using a blower. Exhaust is deadly to breathe and may contain flammable gas. It’s important to be sure no obstructions exist within or near the pipe. Obstructions to the pipe restrict airflow and can cause backdrafting.