What is Furnace Flame Rollout Switch

Posted by: Mas Broto
On:

A furnace is a complex machine with several components, and one of the most crucial ones is the flame rollout switch. It is a safety device that ensures your furnace doesn’t overheat or pose a fire hazard. This blog post will discuss what a furnace flame rollout switch is, what to do when it trips, and how to reset it.

What is a Flame Rollout Switch?

A flame rollout switch is a safety device in a gas furnace that monitors the temperature in the heat exchanger. It is located near the burner assembly and is designed to shut off the furnace if the temperature inside the furnace gets too high.

Furnace Flame Rollout Switch

The switch will trip if the temperature exceeds the predetermined limit, preventing the furnace from igniting until the temperature goes back to normal.

How does the furnace flame rollout switch works?

A furnace flame rollout switch works by detecting the temperature inside the heat exchanger. The heat exchanger is a metal chamber containing the burner’s flames.

The switch is designed to open and cut off the gas supply to the burner if it detects a temperature that exceeds the limit. This prevents the furnace from overheating and posing a fire hazard. Once the temperature returns to normal, the switch will reset itself, and the furnace can start again.

What causes a flame rollout switch to trip?

Several factors can cause a flame rollout switch to trip. One of the most common causes is a dirty air filter. If the air filter is clogged, the furnace will not receive enough air, and the heat exchanger will overheat, causing the switch to trip.

Another common cause is a malfunctioning blower motor. If the blower motor isn’t working correctly, the heat will not be distributed evenly, causing the heat exchanger to overheat.

Other causes include:

What to do when your flame rollout switch keeps tripping?

If your flame rollout switch keeps tripping, addressing the issue as soon as possible is essential. The first thing to do is to turn off the furnace and check the air filter. If the air filter is dirty, replace it with a new one.

If the filter is clean, check the blower motor to see if it’s working correctly. If the blower motor is malfunctioning, it’s best to call a professional to fix it. A professional technician can inspect the vent pipe, gas valve, and heat exchanger for any issues.

How to reset a furnace flame rollout switch – Step by Step

If your flame rollout switch has tripped, you can reset it yourself by following these steps:

  1. Turn off the power to the furnace.
  2. Locate the flame rollout switch. It is usually located near the burner assembly.
  3. Press the reset button on the switch. You should hear a clicking sound.
  4. Turn the power back on to the furnace.
  5. Wait a few minutes for the furnace to reset, then turn up the thermostat to see if the furnace ignites.

If the furnace doesn’t ignite, it’s best to call a professional technician to inspect it for any issues.

How to test a flame rollout switch?

If you suspect that your flame rollout switch is faulty, you can test it yourself by following these steps:

  • Turn off the power to the furnace.
  • Locate the flame rollout switch. It is usually located near the burner assembly.
  • Disconnect the wires from the switch.
  • Use a multimeter to test the switch for continuity. You should see a reading of zero if the switch is working correctly.

If the switch doesn’t have continuity, it’s faulty and needs to be replaced. It’s best to call a professional technician to replace the switch as it requires technical expertise.

How to bypass a flame rollout switch?

Bypassing a flame rollout switch is never recommended as it poses a significant safety risk. The switch is designed to protect your home from a potential fire hazard; bypassing it can cause severe damage or injury. If your flame rollout switch is faulty, it’s best to call a professional technician to replace it.

What is the difference between a roll out switch and a high limit switch?

While the flame rollout switch and high limit switch are both safety devices found in gas furnaces, they serve different functions.

The flame rollout switch is designed to shut off the furnace if the flames from the burner escape from the heat exchanger and start to “roll out” into the surrounding area. This can happen if the heat exchanger is cracked or blocked or if the burners are not functioning correctly. The switch is located near the burner assembly. It is designed to detect an abnormally high temperature and cut off the gas supply to the burner.

On the other hand, the high-limit switch is designed to shut off the furnace if the temperature inside the furnace gets too high. This can happen if the air filter is clogged, the blower motor is malfunctioning, or the thermostat is set too high. The high-limit switch is located on the furnace’s plenum and is designed to detect the temperature in the plenum. If the temperature exceeds the predetermined limit, the switch will shut off the gas supply to the burner.

Final Words

A furnace flame rollout switch is a crucial safety device in a gas furnace that monitors the temperature inside the heat exchanger. It is designed to shut off the furnace if the temperature exceeds the predetermined limit, and it prevents the furnace from overheating and posing a fire hazard. If your flame rollout switch keeps tripping, addressing the issue as soon as possible is essential.

Suppose you need to reset or test your flame rollout switch. In that case, it’s best to follow the steps mentioned above or call a professional technician for assistance.

Find trusted HVAC pros in your area and receive FREE, no-commitment quotes for your project.
Find Pros
Photo of author
Mas Broto
Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.