Can You Bypass A Flame Rollout Switch

Yes, you can. You can take the flame rollout switch out of the equation when running the furnace. In fact, bypassing the flame rollout switch is as simple as disconnecting the power wires connecting to the switch and connecting the two wires directly.

However, this doesn’t mean that it’s a good thing. Read on to find the role of the flame rollout switch and why bypassing it would be a bad idea. We also provide a few alternative ways to troubleshoot and fix your flame rollout switch, so you don’t have to bypass it.

What is the Flame Rollout Switch?

The flame rollout switch is a safety device built into all modern furnaces to shut down the furnace if flames come out of the front of the furnace. You see, when the furnace is operating normally, the ignitor lights the burners, and the flames come alive. However, the furnace burns such that the flames are pulled towards the back of the furnace where the heat exchanger is located.

This way, the heat can be passed through the heat exchanger into supply ducts while exhaust gases are directed outside the house for safety reasons. However, sometimes this process may not go on so smoothly.

For instance, a strong wind that enters the furnace can result in larger, more irregular flames that may pull to the front of the furnace and sometimes “roll out” of the heat exchanger. This is called a flame rollout.

Flame rollouts are extremely dangerous. For one, the front part of the furnace contains critical controls vital to the operation of the appliance, such as electrical wiring and the control board. Excessive heating in this area could damage these parts and, consequently, the furnace.

Additionally, we’re all aware that open flames generate colorless carbon monoxide (and several other toxic gases). It’s tough to “extract” and efficiently vent these gases outside the house when the flame is burning away from the heat exchanger. 

So, by shutting down the furnace whenever there’s a flame rollout, the flame rollout switch protects the appliance, property, and the lives of people in the house.

What Causes Flame Rollout?

Furnace flame rollouts and can happen for many reasons. However, the three most common reasons are as follows;

  • Buildup of soot
  • A blocked flue
  • A cracked or defective heat exchanger
  • Blocked tube in the exchanger
  • A defective flame sensor

How Do I Know if My Flame Rollout Switch Has Tripped?

You may not know right away that your flame rollout switch is bad or has tripped because the common signs may also point to other furnace issues. However, you want to keep an eye out for the following issues;

Evidence of Burns or Discoloration

Since flame rollouts mean that the flame was burning out of the designated zone, one of the first things you want to look for is evidence or the same. Specifically, check behind the cover panel for discoloration or smoke. You can also tell that there was flame rollout if wires and plastic components on the control board are melted.

Of course, a burning smell could also point to potential overheating within the chamber.

Check the Control Board Error Code

Assuming the control board isn’t damaged, you want to check for blinking lights on the removable panel that may signal issues within the furnace.

If you find the lights, count the number of blinks between pauses. Then cross-check with the sticker or card inside the cover panel or control board to find out if it’s saying that there was a flame rollout or overheating. Alternatively, cross-check with your manual.

The Blower Fan Runs but no Heat

As we’ve mentioned repeatedly, the flame rollout switch automatically shuts the furnace in case of a flame rollout or overheating in undesignated zones. The burners will go off, meaning you can forget about enjoying the warmth until you rectify the issue.

However, since the blower motor runs even following flame rollout, you may get cold air from the supply vent. You’ll also hear the humming blower motor.

Flames Burning Outside the Combustion Chamber

Yes, scary as it is, it happens sometimes. For instance, if you were working on the furnace with the cover off following evidence of overheating, you may see the flames first-hand rollout out of the combustion chamber before the furnace goes off. A normal furnace flame is gentle, blue, and conical.

It will also appear to move away from you. However, there’s a problem if the flame is yellow or orange and seems to burn towards you. Of course, it’s extremely risky, so we strongly advise against igniting the furnace just to witness a flame rollout.

The Switch is Dead, or the Reset Button has Popped Out

Flame rollout switches are either “one-time” switches or have a reset button. One-time flame rollout switches are gone once they trip. The switch must be thrown away and a new one installed. So, if it’s dead, you can conclude that there was overheating or a flame rollout.

Meanwhile, for the second category, the reset button pops out if the switch is tripped. So, if it’s popped out, you can tell that there was overheating or a flame rollout.  

Why Does My Flame Rollout Switch Keep Tripping?

If your flame rollout switch keeps tripping, something might be causing a flame rollout whenever the furnace attempts to reignite. Alternatively, you may have a bad or defective flame rollout switch. The latter is not very common as flame rollout switches are very durable.

But if you can’t find any signs of overheating or a flame rollout, but the switch keeps tripping, then you most likely have a defective switch.

Can You Bypass the Flame Rollout Switch?

Yes, you can bypass the flame rollout switch. Just keep in mind that bypassing the rollout switch exposes you and the appliance to significant risk.

How to Bypass the Flame Rollout Switch

However, if you feel that bypassing the switch can help you confirm beyond doubt that the lame rollout switch is broken or defective, here’s how to bypass it;

  1. Turn off the furnace: Switch off the furnace using the onboard switch, turn off power at the breaker, and turn off the gas supply at the main valve.
  2. Open the furnace: Remove the front panel/cover to access the furnace’s internal components. You may need a screwdriver for this process.
  3. Locate the flame rollout switch: The flame rollout switch is typically located in the blower compartment. It’s a small button-shaped device with two wires connecting to it. All furnaces have at least one switch, though some have up to three.
  4. Remove the wires: Gently pull the wires off the flame rollout switch terminals. It should be a fairly straightforward process.
  5. Connect the wires directly: Holding one wire in each hand, connect the two and twist them together. Doing so completes the furnace circuitry while removing the flame rollout switch from the equation.

That’s it! You’ve bypassed the furnace flame rollout switch. If the furnace works without the rollout switch, the switch is damaged, defective, or tripped.

How to Fix a Flame Rollout Switch

There are four things you can do to address issues related to flame rollout switches. It depends on the underlying problem.

  1. Reset the switch: Resetting it will easily fix the problem if you’re dealing with a defective switch. Locate the reset button on the back of the rollout switch and press it back into the switch.  
  2. Repair the switch: If the switch keeps tripping, but there’s no sign of overheating or flame rollout, call an HVAC pro to check and repair it.
  3. Replace it: However, if resetting and repair don’t fix the problem, you need to replace the flame rollout switch. A new one costs around $90.
  4. Fix the underlying causes: Interestingly, sometimes you don’t need to touch the flame rollout switch. Just address the underlying issues, such as soot buildup and flue blockages, restart the furnace, and watch the problem disappear. However, sometimes you may need to reset the switch after fixing the underlying issue. 


There you go. Now you know about furnace flame rollouts, what causes the rollouts, signs of a flame rollout, and the role of the flame rollout switch.

You even know how to bypass the flame rollout switch and what to do if your flame rollout switch is defective, dead, or tripped. Don’t hesitate to call your HVAC technician for further advice