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A furnace flame sensor works by detecting the presence of a flame within the furnace. As the gas valve opens to begin the combustion process, the current is sent out from the sensor in order to detect the presence of heat from a flame.
How do I know if my flame sensor is bad?
First, check for your gas burners to light up and then go out after a few seconds. This is the most common sign of a sensor issue. Second, if you can actual see soot covering the tip of the sensor, it’s time for a cleaning. If you look at the tip and it’s black, it’s time for service.
Can you bypass a flame sensor?
Shut off power and gas to the furnace. Remove the sensor. Clean away soot and corrosion with a clean emery cloth. Reinstall the flame sensor.
What causes a flame sensor to go out?
As with any piece of equipment a simple reason could be that dirty flame sensor just goes bad. However a more common reason is that it is just dirty. It is a sensitive sensor so any type of dust or carbon buildup could cause it to malfunction.
What will a bad flame sensor do?
What happens when a flame sensor goes bad? Without a flame sensor, your furnace will keep emitting gas even when there’s nothing to ignite it, resulting in hazardous gas buildup. If your flame sensor is dirty or faulty, it will automatically shut down the heating unit if it doesn’t detect a flame.
How does a gas furnace flame sensor work?
A furnace flame sensor works by detecting the presence of a flame within the furnace. As the gas valve opens to begin the combustion process, the current is sent out from the sensor in order to detect the presence of heat from a flame.
What would cause a gas furnace not to ignite?
The Pilot Light (Faulty Ignition Sensor) The pilot light or ignition sensor is usually the most common issue when your furnace will not ignite. This is typically the problem if you can hear your furnace click on but it does not fire up. If the sensor or ignitor is dirty, it will need to be cleaned.
How long do flame sensors last?
Flame sensor lifespan If you’ve just replaced the sensor or had a new furnace installed, you can expect the flame sensor to last for about five years. The average lifespan of a furnace is 15 to 30 years, so you can anticipate a flame sensor replacement once or twice over the course of your homeownership.
Will furnace run without flame sensor?
The flame sensor is an important safety feature inside a furnace. Without the flame sensor, if the pilot light goes out but the gas valve remains open, the gas will not burn and will seep out of the furnace. This is a dangerous situation that can result in gas poisoning or even an explosion.
Are flame sensors universal?
Universal flame sensors: You might not need an exact replacement part. Universal sensors are available too. They are available at Home Depot, Menards or other building supply store.
Can you touch a flame sensor?
Please do not confuse the flame sensor with an Ignitor. We do not want to touch the ignitor at all. If you touch an ignitor it can shorten the life of the ignitor or it could break. Clean your flame sensor with steel wool or emery cloth (fine sandpaper).
Why do flame sensors get dirty?
What Causes a Flame Sensor to Get Dirty? It’s possible for a flame sensor to go bad; but more often than not, it is not broken, just dirty from carbon buildup. Because a flame sensor has a very low tolerance for variations in the reading it takes, the slightest coating of carbon can cause it to misread and shut down.
Why does my furnace start up and then shut off?
The HVAC filter gets caked with dust and other debris over time. This causes short-cycling as you’ll notice your furnace running for a short while before turning off. The heat will build up, and your furnace will shut down as a safety mechanism. Wash or replace your furnace filters when necessary.
Why does my furnace blower turn on and off constantly?
If your blower is constantly turning on/off when the furnace isn’t heating… you most likely have a bad fan limit switch. So if your furnace blower is turning on and off when the furnace isn’t in a heat cycle, it usually means the fan limit switch is defective.
What is flame sensor made of?
A flame sensor is nothing more than a stainless steel rod partially encased in porcelain. By itself, it does nothing. There are no moving parts, no switches. When attached to a control module, the module sends out an A/C voltage to the sensor.
How does a 1 wire flame sensor work?
The flame sensor when heated up acts like a cathode of the vacuum tube. It emits electrons which flowing to the ground through the flame, like in the vacuum diode.
Why is my heat not kicking on?
If your furnace is not kicking on, it can be an issue with the thermostat. You should first make sure that the thermostat is switched to the heating function. You may also have an internal problem with your thermostat, which needs to be repaired by a professional.
Why is my furnace not staying lit?
Probably the most common issue when dealing with a furnace that will not stay lit or ignite consistently is a dirty flame sensor. The flame sensor acts as a communication vehicle with the circuit board and tells it when a flame is lit inside the furnace.
Why is my furnace running but no heat?
Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. If the blower is running but no heat is coming out, replace the filter.
How much does it cost to replace a flame sensor on a furnace?
You can expect to pay between $350 and $500 for a new flame sensor if you call a furnace repair company.
