How to Test a Flame Sensor

A flame sensor plays an important role in the safety of your furnace. Its job is to make sure that the gas is being burned in the furnace instead of leaking out and building up in other places. A flame sensor can detect a weak or non-existent flame and shuts down the furnace in order to avoid gas-related issues. A dirty or broken flame sensor can lead to an emergency service call for gas build-up or a furnace that won’t turn on. This could end up costing a of of money, so regular testing and cleaning is the best idea to avoid unforeseen costs or emergencies.

We’re not all furnace experts, if at any point during the process you need a little help, reach out to Pro Duct Solutions and we’ll be right there to help you out. Pro Duct Solutions is a fast-growing Ottawa-based HVAC company and we pride ourselves on providing a comprehensive set of services. We can help you with furnace maintenance and repair as well as duct cleaning and installation. Check out the handy online booking tool on our website or give us a call with any questions.

What is a flame sensor? What does a flame sensor do?

The flame sensor is an essential safety device used in your furnace. It is connected to the pilot light and ensures that there is always a flame burning in the furnace. This is a really important feature as it makes sure that your furnace isn’t emitting gas when the light’s out. Without the pilot flame, the gas doesn’t get burned up and can create dangerous buildup of gasses inside your home. The flame sensor uses an important process called flame rectification. To complete this process, the flame sensor unit sends electrical currents through a flame rod which then detects the size of the pilot light. If the flame is too low or non-existent, it shuts off the gas.

If your flame sensor turns off the gas, it doesn’t always mean there’s something wrong with the furnace. Sometimes it can indicate a flame rod which needs cleaning. To determine whether the unit is dirty or broken, you need to conduct a test.

How to test a flame sensor?

To ensure that your flame sensor unit is working as it should, it’s a good idea to perform regular tests. The first step is to get a tool called a multimeter. It’s an instrument which is used to test electronic currents in a number of electronic items. You want to make sure your multimeter gives readings in micro-amps.

  1. Turn off the flame.
  2. Detach the flame sensor wire from the flame sensor unit.
  3. Attach one wire from your multimeter to the flame sensor wire and the other one to the unit where you unplugged the wire.
  4. Turn on the unit.
  5. Look for a reading between .5 and 10 micro-amps with the normal range between 2 and 6. Your user manual should indicate the specific reading that is ideal for your unit.

How to clean the flame sensor unit.

Once you’ve tested the unit and determined that isn’t working as it should, you may want to try cleaning the flame rod. This is a fairly easy process and could result in saving money by avoiding calling a technician in to do repairs. However, if you feel apprehensive about any step in this process, it’s a good idea to give us a call at Pro Duct Solutions. We can provide advice or we can come in and take a look at the flame sensor and make sure everything is running as it should.

  1. The most important step is to turn the furnace off. For ultimate safety, turn it off at the breaker.
  2. Since the flame rod is constantly exposed to flame, it’s going to be hot. Make sure the unit cools down before you touch it.
  3. Carefully remove the flame rod.
  4. Clean the rod by lightly scrubbing with soft steel wool or a rough sponge. Be careful not to press to hard as you risk removing the coating.
  5. Put the rod back, turn the furnace back on, and conduct another test. If the reading is within the right range for your furnace, then your job is done.

What to do if the cleaning doesn’t work?

If cleaning the rod didn’t improve the ratings you see on your multimeter, it’s time to call in Pro Duct Solutions.  We will come in and perform a thorough inspection of your entire furnace system. We will get to the root of the problem and ensure that everything is working as it should by the time we leave.

Don’t forget, if you’re having any issues with your furnace whatsoever, please give us a call at Pro Duct Solutions and we can help improve the functioning of your entire HVAC system. Our expert technicians use the most cutting-edge equipment to ensure that we find the right solution to your problem.

Book an appointment with Pro Duct Solutions
Small Author Photo

Related Posts

No items found.

Subscribe to Technician's Blog Posts

Stay informed

Thank you! Your submission has been received!

Oops! Something went wrong while submitting the form