Is It Safe to Just Reset a Flame Rollout Switch?
Yes. It is safe to reset the rollout switch a time or two to see if it tripped for a minor reason – not a furnace repair issue.
Now, if you are asking this question, you already know enough about a gas furnace to know that there is such a thing as a flame rollout switch. The flame rollout switches on some furnaces are designed so that if they trip, they cannot be reset, but must be replaced. Most furnaces, however, have a flame rollout switch (or switches) that can be reset.
In case you have found this article and aren’t familiar with the subject, but your curiosity prompts you to read on, there are a few things that will help you understand whether or not it is safe to just reset a flame rollout switch.
The Flame Rollout Switch Described
Briefly, a flame rollout switch is what might be called a “safety switch” in a gas-fired furnace. It is located near the area where the gas flames are projected into the interior of the furnace during a heating cycle – that is, when the thermostat has called for heat. With an access panel removed from the side of the furnace, these flames can be seen, and they look similar to the blue flame from a gas torch.
If a condition exists that prevents the flames from flowing into the furnace smoothly, they will “rollout”, or flow backward out of where they are supposed to go. This will result in excess heat contacting the flame rollout switch, which will trip and stop the gas from getting to the burners. The flames will go out, and possible damage to the furnace will be prevented. In some situations, it might even prevent a fire or dangerous gases from harming the occupants of the building. That’s what the flame rollout switch is there for.
There are more details in our comprehensive FAQ guide, All You Need to Know About the Flame Rollout Switch.
What Causes Flame Rollout Switch to Trip?
There are several conditions that will cause a flame rollout switch to trip. While each of them is different, they all have one thing in common: they interfere with the smooth flow of the gas burner flames as they travel into and through the heat exchanger, then out the flue to the outside environment. They include: a cracked heat exchanger, a blocked or partially blocked flue or chimney, and low gas pressure. Any of these conditions can result in those burner flames not being drawn into the furnace’s heat exchanger. Instead, they can “roll out” into the area of the furnace where critical control components like the control board are located – and damage them quickly with heat near 2000F.
Resetting the Flame Rollout Switch
As mentioned above, if the flame rollout switch trips, it has detected excess heat in the wrong part of the furnace and has shut off the gas supply to the burners. Most of these switches can be reset, so that the furnace will once again start up when the thermostat calls for heat. It must be remembered that the flame rollout switch is a safety device. It tripped for a very important reason. However, in a rare instance, it may have tripped for some unknown reason other than an actual rollout of flames. And yes, it can be reset without risk. If the furnace has a flame rollout problem, the flame rollout switch sensor will detect it, and trip to stop the burners.
How to Reset a Flame Rollout Switch Step by Step
If you do decide to reset your flame rollout switch, follow these steps carefully:
Step 1: Safety First
a. Turn off the power that controls the furnace. There is a circuit breaker in your main electrical service panel. There is also often a switch somewhere on the side of the furnace that might look like a light switch. Either one will kill the power to your furnace.
b. Turn off the gas to your furnace. This is normally located beside the furnace on the gas line that looks like a metal pipe with a knob on it. Turning the knob ¼ turn one way or the other will shut off the gas. Tip: The gas shut-off usually has a long handle. When the handle runs parallel to the gas line, it is open. When perpendicular to it, the valve is closed.
step 2: Remove the Panel
There are often two removable panels on your furnace, one above the other. The top panel is where the burners and control elements will be found. With the panel removed, you will be able to see the burner assembly containing the gas burners (usually between 2 to 5 burners).
step 3: Locate the Flame Rollout Switch(es)
The flame rollout switch (possibly more than one) is generally located just above the gas burners. They are small devices with two wires connected to each of them. You can locate them by following the gas line to the burner ports. The switch is located near the ports. Be sure to check for more than one. If a switch is tripped, the small button in the center will be protruding outward. It may or may not be red.
step 4: Reset the Flame Rollout Switch
After making sure that the furnace has fully cooled down, press the small button inward to reset the switch. It might take a little “oomph” until it clicks, indicating it has been reset. This will enable the gas valve to open and allow the burners to fire again when the next heat cycle begins.
Tip: If you push down the reset button and it doesn’t click, just returns to about the same position it was in, the switch might not be tripped. In this case, you’ll have to try other furnace troubleshooting options.
step 5: Turn the Gas and Power Back On
If your furnace has a power switch near the furnace, we recommend that you turn this on last, so you will be able to observe the burners when they come on. If you see any bouncing of the flames on even one of the burners, or if it is obvious that some flames are coming back toward you, this is flame rollout and the reason the switch tripped in the first place. In this event, you might as well shut off the furnace rather than waiting for the flame rollout switch to trip.
step 6: Only Reset the Flame Rollout Switch One or Two Times
If you observe flame rollout with the panel off, or if the flame rollout switch trips again, the safest practice is to kill the power and gas to the furnace. Do not keep resetting the switch. This safety device has done its job to shut down the furnace with a problem and possibly prevent serious damage to the furnace and/or occupants of the building. It’s time to call a local HVAC company to find out what the problem is.