What happens when the flame sensor goes bad?

A flame sensor is a very integral part of your furnace’s furnace and the overall safety of your household. 

As the name suggests the device does exactly what you expect it to. A flame sensor senses flame and ensures the furnace is fired up. If there are no flames, and the gas supply is on, there might be a gas leak in your house waiting to turn catastrophic with the light of a matchstick or gas stove. 

Whether your flame sensor is functioning properly or not, it will never not cut off the gas supply. In fact, a malfunctioning gas supply does exactly that: cuts off supply even when the furnace is burning and raging hot. You can identify a faulty flame sensor by looking for the following defects 

1. Short cycling 
2. Cracked porcelain on the flame sensor frame 
3. The flame sensor has visible signs of soot or corrosion 

How to fix a defective flame sensor?

If you suspect the flame sensor is causing issues with your furnace’s performance, you will have to remove the furnace access cover to locate the device. A flame sensor is a metal rod with yellowish or white porcelain near the mounting end. This porcelain insulates the sensor. It is usually mounted outside the burner assembly and has a single wire attached to it. 

Once you have successfully located the sensor, you would want to carefully follow the steps mentioned below for a quick and safe self-diagnosis of your flame sensor. 

1. Turn down the power supply to your furnace
2. Cut off the gas supply by turning the valve to the “Off” position.
3. Carefully remove the sensor mounting screw and gently pull the device out for a keen visual inspection.
4. In case the insulation is intact but you notice soot or corrosion around it, a simple cleaning should solve the issue.  
5. On the flip side, if the porcelain casing is cracked, you see other broken parts, or if cleaning does not help, you would require a replacement for the device. 
6. Having cleaned the sensor, return it to its exact original position and screw it properly.
7. Turn the power back on, restore the gas supply and ignite the furnace. 

How to clean a dirty flame sensor?

Flame sensors are delicate devices and you must be very careful and gentle despite the level of dirt and soot as small indents and grooves can accelerate carbon deposition thus making it more susceptible to malfunction. To clean a soot-ridden flame sensor you must always use an emery cloth of fine grit. Fine-grit has small, and more grit than medium grit cloths.

A fine-grit as it is less likely to cause any grooves or marks on the sensor rod. The soft metal of the flame sensor can easily get scratch marks which can collect carbon from the burner flames. For a perfectly cleaned flame sensor, you would want to leave a smooth, polished surface on the flame sensor’s meal rod. 

How to replace a defective flame sensor? 

We understand that putting back a replacement may get tricky and if for some reason you still feel like undertaking the task, we have got you covered. 

1. Remove the mounting screw and take the sensor out carefully.
2. Detach the wire from the sensor to completely disconnect the device from the furnace.
3. Put it back to the designated space and remount the screw. 
4. Carefully attach the wires to the new sensor. 

You can get a replacement for your flame sensor from a local supplier that sells furnace parts or online stores. You must be careful to get the same make and model as your old sensor otherwise your new purchase may end up being useless. You can also try universal flame sensors which fit most furnaces and do not require exact measurements and numbers. 

What if the furnace still does not work?

If you have closely followed the aforementioned steps for each task and yet do not see your furnace issues going away, the problem may likely be something else and you need a furnace maintenance Oakville. The important thing to note here is that problems with your furnace do not always point to a specific source. Many furnace issues will have similar visible signs making it difficult for owners and technicians alike to resolve the issue. 

It may be confusing and you may think you would incur a lot of expenses but the silver lining is that in the process of finding the actual fault, a lot of other components, operations, and interconnected systems, also get a check-up. Such sudden maintenance has a range of benefits that can save you a lot of money and trouble. If you were behind on routine maintenance, or if your furnace is quite old, an impromptu service will always be beneficial. 

Flame sensor replacement expenses

Replacing a flame sensor is quite inexpensive whether you are doing it yourself or through a furnace maintenance Oakville. If your flame sensor only needs a thorough cleaning, a fine-grit emery cloth will cost only about $5.a replacement might set you back anywhere between $6 to $75 depending on the type and model of the sensor. The average flame sensor can be bought for less than $40. 

On the other hand, if you do not feel comfortable performing such tasks yourself, you can always get in touch with trusted Brighton furnace repair services. Professional cleaning and check-up will incur a service charge along with the cost of the replacement if necessary. A thorough flame sensor service may set you back about $200. We have taken into consideration the maximum cost for a replacement which is $75. 

Rates may vary largely but ensure that you avail services from trusted contractors that provide sufficient warranties on parts and services. 

At Martino HVAC, we strive to understand your HVAC requirements and complaints thoroughly to implement the best possible solution. Our team has over 30 years of experience and is qualified to deliver a seamless service experience. Call us today to experience an unmatched standard of service.