Can You Cut Or Bend A Flame Sensor? Should You?

When replacing a flame sensor, you might find that the replacement isn't at the same angle or length as the original. You may wonder if it is okay to bend or cut the rod to make it fit. Luckily, we have done the research for you, and here is what we found.

Yes, flame sensors can be bent or cut when necessary. Use a side-cutter or hacksaw to cut the flame sensor to the correct length. Many universal flame sensors come with angle guides and protective sleeves to help you bend them safely.

The flame sensor generates an electric current to verify that there is a fire burning inside the furnace. A current is discharged from the sensor at the same time the gas valve is opened to initiate the combustion process. This allows the sensor to detect the presence of heat from a flame. Keep reading to get detailed information about flame sensors.

A home Goodman high efficiency furnace with Bradford White Residential gas water heater & an Generalaire humidifier, Can You Cut Or Bend A Flame Sensor? Should You?

Can You Cut Or Bend A Flame Sensor? Should You?

A flame sensor can be cut or bent.  To make sure that the end of the sensor rod is positioned more appropriately in the pilot light, you can give it a small bend (about 20 degrees). However, be careful to avoid damaging the ceramic insulation in any way. The burners will have a more reliable ignition as a result of this.

By bending the flame sensor, the flame rods will be arranged in such a way that one end of each flame rod is in direct contact with the flame of the burner, while the other end of each flame rod is connected to the ignition board of the furnace. To cut a flame sensor, you need a side cutter, hacksaw, or bolt cutter.

A flame sensor can be found inside the furnace. It identifies and verifies whether or not the furnace is ablaze with a flame from within. It performs its function by determining whether or not the furnace contains an active flame. When the flame is detected by the sensor and the furnace is operating normally, the heating process continues.

However, the furnace automatically turns off if the flame sensor does not detect the presence of a flame within ten seconds of the gas valve being opened. 

Click here to view this flame sensor on Amazon

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Many universal flame sensors are designed to be bent or cut and will come with guides to help you do so. Check out the video below to see the process for the Emerson White-Rodgers flame sensor:

What Metal Is A Flame Sensor Made Of?

The majority of flame sensors are made up of a rod made of stainless steel that is partially covered in porcelain. Flame sensors have no effect by themselves. There is not a single moving part, and there are no switches. Once the sensor has been connected to a control module, the module provides an alternating current voltage to the sensor.

How Do You Test A Flame Sensor?

To do a test on the flame sensor, follow these steps:

Step 1: Turn Off The Device

Ensure the furnace is well grounded. You can do this by powering down the furnace and getting an ohm reading between the neutral and the burner assembly/manifold. You should only read a few ohms of resistance at most. The lower the ohm reading, the more grounded the component is.

Step 2: Make The Necessary Connections

To make sure that the polarity is correct, connect the hot (L1) terminal to the hot terminal, and the neutral (N) terminal to the neutral terminal. It is important that the rod be positioned in such a way that it will be covered by the flame.

Check the instructions provided by the manufacturer because many boards contain test pads that read in dc volts, a light to indicate a low flame reaction, or a display that shows a flame response.

Get a meter that reads in micro-amps. Use a decent quality meter for this and make sure the leads are in the correct positions. Connect the leads in series. This implies you have to separate the wire from the rod, connect one meter lead to the rod and the other to the wire taken from the rod.

Step 3: Check The Readings

When the burners start to burn, you should see a reading of anywhere from 0.5 to 10 micro-amps, depending on the furnace. The majority of people get readings between two and six. However, check the manufacturer’s specs.

How Many Volts Is A Flame Sensor?

If a voltmeter is used to measure the voltage that exists between the flame sensor wire and the burner, the flame sensor voltage should fall within the range of 40-80 volts AC.

In the event that the voltage is outside of the acceptable range, there will be no sufficient electrical pressure to force the current into the flame.

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Should I Clean Or Replace Flame Sensor?

A home high efficiency furnace.

Cleaning and maintenance of the furnace should be performed on a seasonal basis in order to extend the life of a flame sensor.

If you give the sensor of your heating system a thorough cleaning at least once a year, you can avoid having to call for emergency heating services in the middle of the winter even if your heating system seems to be operating smoothly.

However, the safety of your system is of the utmost significance; hence, it is always preferable to be on the safe side rather than regret and replace the flame sensor if it is not functioning properly.

It is recommended that you replace the flame sensor every two or three years as a preventative measure even if the flame sensor is in good operating order and performing as it should.

Why Do Flame Sensors Fail?

A home high energy efficient furnace in a basement

A flame sensor may malfunction or fail for different reasons. A dirty sensor is the most prevalent. Metal will rust if left exposed to the byproducts of any form of combustion for an extended period of time.

As a result, since flame sensors are metal constructed, it means it's susceptible to rust, which can prevent it from detecting the flame effectively.

Another potential reason a flame sensor may fail is a sensor that is either faulty or has an insulator break. It's possible that a short in the component's electrical wiring has severed its connection to the control board.

What Happens When a Flame Sensor Goes Bad?

A home Goodman high efficiency furnace with Bradford White Residential gas water heater & an Generalaire humidifier.

If the flame sensor is malfunctioning, you should have a professional HVAC technician check out your system. If the flame sensor goes bad, your furnace will keep releasing potentially deadly gas even when there's nothing to light it. Without a clean or malfunctioning flame sensor, the heating system turns off if it senses that a flame isn't present.

After three consecutive shutdowns, most furnaces will lock out the ignition for safety purposes. Constantly tampering with a defective flame sensor in a furnace is not only highly inconvenient, but it can also lead to problems in other furnace components and a decrease in the system's overall performance.

A flame sensor helps make certain that the furnace doesn't call for gas if the flame is not lit correctly. Anyone who is inside the house is protected from the dangerous accumulation of gas thanks to this measure. Additionally, it helps to ensure that the gas is not being wasted by being run while it is not being used.

Explosions can be avoided in the home by minimizing the gas inside the home, which reduces the likelihood that the home will become filled with gas and that a spark will ignite the gas. 

How Many Ohms Should A Flame Sensor Read?

electrician measurements with multimeter tester

When measured with an ohmmeter, the flame sensor should show a reading of 0 ohms; nevertheless, a reading of 1 to 2 ohms is considered acceptable. On the other hand, when a flame is present, the resistance between the flame sensor and the ground increases to many thousand times that value.

When there is no flame present, the resistance between the flame sensor and the ground should be infinite, or at least several hundred megaohms. A standard multimeter would not be needed for measuring such a high value of resistance.

To Wrap Up

If you think your flame sensor needs to be cut or bent, it is okay to do so. To cut a flame sensor, you will be needing a side cutter, hacksaw, or bolt cutter. The flame sensor is an essential safety feature in a furnace. Thus, when the sensor fails, you can also replace it. 

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