Spider webs, dust, or dirt buildup can block the pathway of the pilot light, leading to a weak flame. These obstructions prevent the proper flow of gas and air needed for a strong and steady pilot flame. It's essential to regularly inspect and clean the area around the pilot light to ensure unobstructed operation.
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.
One possibility is the clogging of burner ports. The burner ports are the little openings in the stovetop through which the gas flows. If they become blocked with food or particles, the gas will not be able to flow correctly, and the flame will be low. A failing gas valve is another possibility.
The most common symptom of a bad flame sensor is when the furnace reaches ignition and the burners shut down after only a few seconds. If it runs longer than that, the problem is likely elsewhere.
If the heat exchanger rusts through or cracks, flue gases, including deadly carbon monoxide could leak into the home resulting in illness and possibly death of the occupants. Carbon monoxide poisoning can produce headaches, flu like symptoms, and even death.
Troubleshooting Weak Flames
Checking for any visible blockages, ensuring proper ventilation, and holding the equipment can help improve gas flow and subsequently strengthen the weak pilot flame. If these measures do not resolve the problem, contacting a professional technician from your gas company would be advisable.
They will cost around $200 if it is done during regular maintenance service. Likewise, flame sensors can become too dusty and malfunction, but a thorough cleaning can restore them. However, if it's too late and you need to replace the flame sensor, expect to pay between $80 and $250.
Flame sensors have an average lifespan of about five years. Therefore, you can expect to need to replace it at least twice before replacing your entire heating system.
Clean out the burners and venturi tubes (burner stems) to clear any dust, dirt, or spider webs. These kinds of blockages may lead to a low or yellow flame. You can use a garden hose or air compressor to spray straight down into the burners; likewise, you can spray into the venturi tubes.
Ideally, your natural gas furnace should emit flames that are either blue or almost completely blue. HVAC repair companies will tell you that a furnace emitting raging blue flames with light blue triangles at the center indicate optimal furnace operation. It's okay if there are small hints of yellow.
A properly working pilot light flame should be a cone-like shape, bright blue in color and yellow at the tip. A lazy orange/yellow flame means the furnace or water heater isn't getting hot enough to heat the thermocouple to the point where it triggers the gas valve to open. The thermocouple is faulty.
There is a work-around to waiting. If there is no safety risk (like a gas leak), a furnace can be reset to bypass this wait. Turn off the furnace's power switch and wait 10 seconds before turning it back on.
The Furnace Won't Come On.
If you notice your home getting colder and colder, yet the Furnace never comes on, no matter how high you set the temperature, this could indicate a problem with the ignitor.
The flame sensor plays an important role in the safe operation of a gas furnace. Most newer furnaces don't utilize the old-fashioned pilot light flame to ignite the gas burner. Instead, when the thermostat opens the main gas valve to the burner, the burner is lit by an electronic igniter.
1. Will a furnace run without a flame sensor? No, a furnace will not operate without a flame sensor.
Having a working flame sensor is critical for a functioning furnace. While most furnaces last for 10 to 20 years, flame sensors have a much shorter lifespan of about five years. Usually, when a flame sensor goes bad, the best route is to replace it outright.
This can be caused by a loose fan belt, or a dirty motor. Solution: First, clean the blower fan and the area around it. It has to deal with a lot of air, so it naturally becomes dirty over time. If that doesn't fix it, the fan belt probably needs to be replaced.
If your flame is yellow or orange, or if you see pops of yellow or orange, that is a sign that you have a combustion problem that should be addressed by a professional. Long streaks of any color, such as yellow, orange, or green means your furnace needs adjustment or cleaning from a professional HVAC technician.
Furnaces have an average lifespan of around 10 years, and most exchangers tend to go out around this time. If your furnace is close to this 10-year mark, a new furnace is likely a better investment. If your furnace is relatively new, a new heat exchanger may be worth it to avoid early furnace replacement.
Changes In How The Flame Looks
In a normal gas furnace, the flame will usually appear blue. A blue flame means that your furnace is working as it should. If this flame turns yellow, however, it might mean that your burner needs to be cleaned, or worse, that the heat exchanger is cracked.
However, most gas furnaces typically last between 15 to 20 years before efficiency declines and repair costs increase, so it's wise to consider replacement around the 15-year mark to ensure optimal performance and safety.