Pilot Light Is Lit But Furnace Won’t Kick On. The furnace may not turn on if the pilot is lit but does not touch the furnace. The gas valve of the appliance may be the problem. The control board may not let the furnace light on even though the pilot is on.
I was going to start my heater and enjoy a nice hot chocolate as I got wet outside. After changing, I turned my heater on, but it didn’t on. I checked and saw that the pilot of my heater was lit, but the furnace of my heater was not turning on.
I thought of restarting the heater, but restarting the heater didn’t work either. The furnace needed to replace. That’s what I thought, but being lazy helped me as I checked the internet rather than going to a professional. I fixed my heater with the internet’s help.
Read to learn!
Pilot Light Is Lit But Furnace Won’t Kick On
If your furnace doesn’t turn on when the pilot of the heater is lit, then you have a bad heater issue. The heater first can get damaged for a lot of reasons. The issue with the furnace may be related to the heater’s thermostat. The gas line of the heater may be off.
The thermopile of the heater may not sense the pilot’s flame. The furnace itself gets a problem with it too. The airflow may have been restricted for some reason. The burner line may have corroded. The jet line can get corrosion too. The air filters may have clogs.
Gas issue
If the pilot light is lit, then that means you have gas, but the gas may only be enough to light the pilot. If the furnace is not turning on, then the gas may be less.
The gas can be seen less through the light of the pilot. Good gas will show a blue light on the pilot, but if the light of the pilot is orange, then the gas may not be enough.
The gas may not be suitable for your heater, or the pressure of the gas is not enough to light the furnace. If there is a problem with the heater’s gas, you need to get proper gas to your heater.
The gas should be enough pressure for the furnace as it’s for the pilot, and the color of the pilot light should be blue. Try completing the gas requirements and move on. Read more below!
Gas line issue
If there is a gas problem, then the gas line will show problems too. The gas may be turned off, so check the gas first and see if you have it coming from behind.
Check the shut-off valve and see if it’s on or not. You can check the gas by checking other appliances that run on gas, like the stove or a gas lamp that work.
The gas may be flowing to other appliances, so check the supply of gas that is linked with the furnace itself. The gas supply to the furnace may be the issue. The gas line to the furnace may have clogs.
The furnace won’t get gas with clogs in it. The close-in gas line should be cleared by a professional. The gas line can leak from behind, so get a professional after evacuating others.
Thermopile issue
Sometimes the burner light is on, but the furnace won’t work because of the thermopile. The thermopile fails to sense the flame from the burner. Without the thermopile sensing the flame, the furnace has no way of turning on as the sensing is an important factor for the furnace to turn on. The pilot light may remain lit, but until the thermopile sense the flame, the furnace won’t light.
The thermopile has a rusting issue, and the rust doesn’t let the thermopile sense. Corrosion envelopes the thermopile am makes it lose its sensing ability.
If you think the thermopile is not sensing, check the output from your thermopile with a meter. 350mV is the least output you may take as normal. Anything lesser than 350mV is not enough. Remove the thermopile if it’s less than 350mV, remove the thermopile’s rust, and put it back.
Thermostat conspiracy
The thermostat may have conspired against your furnace, and that’s why the pilot remains lit, but the furnace doesn’t. The thermostat may not be set to heat as a mistake.
So you need to turn the thermostat’s heat on. There can be a temperature conspiracy with the thermostat. The thermostat may have been set to heat at a temperature that is lower than the room temperature, and thus the furnace doesn’t turn.
The fan switch should’ve turned on if the above reason doesn’t work. The fan will help and force the furnace to blow air. Check if there is an error code relating to the thermostats.
The thermostat these days shows errors through codes, so check your thermostats. If there isn’t any error in your thermostat, then the thermostat may either be old or the thermostat has a problem that cannot be displayed in codes.
Thermocouple problem
If the thermostat is fine and so is the thermopile, then the last Thermo-thing you need to check is the thermocouple. The thermocouple of the burner won’t light if there is a problem with it. The thermocouple problem is the same problem that was faced by the thermopile.
The problem with the thermopile was rust, and the thermocouple will have the same problem. The corrosion and rust on the thermocouple affect the temperature a lot.
The temperature affects the furnace a lot and the burner too. The thermocouple has an easier fix, as the rust on the thermocouple is easy to remove. You can vacuum the rust on the thermocouple.
The vacuum will take the dust and debris from around the thermocouple away. The rust will be sucked in the vacuum as well. Use the vacuum when the burner and the thermocouple are cool for safety. The thermocouple can be replaced if it doesn’t ignite.
Closed vent
The airflow in the burner is really important. The fire cannot remain where the airflow is not proper, and that’s why the fire doesn’t remain in a vacuum. The burners have vents for this purpose.
The airflow remains smooth because of the vents. The closed vents won’t let the heater ignite at all. The flame rollout switch may be the reason that the vents have closed. The fuel gas spill switch is another reason the furnace doesn’t turn on.
The furnace doesn’t get airflow if any of the switches become faulty. The main burner won’t light because of the switches.
The vents should be open for you to get the airflow you need. The closed vents hen open will bring the airflow back, and the furnace will ignite. The switches may be faulty, so the switches should be replaced with new ones for airflow.
Pilot issue
The issue that doesn’t let the furane ignite may be because of the thing that ignites it. The pilot ignites it, but sometimes the reason the ignition doesn’t happen is because of the pilot.
The pilot itself can remain lit, but that doesn’t mean the pilot will ignite the furnace. The reason that the pilot is ignited is that the flow and everything are correct, but still, the furnace isn’t lit.
The reason for the furnace problem may be the pilot. The pilot may be on, but it may not have any contact with the furnace. The contact between the furnace and the pilot is not clear because of the distance.
The pilot may have been moved to form its position, and now the pilot is far from the furnace. The distance doesn’t let the furnace light, so push the pilot back to its place and make it near the furnace.
Furnace itself
The pilot light may have the right distance from the furnace, and the fire may even be in contact with it, but there still may not be fire. The switch inside the furnace may be off, or someone accidentally switches the furnace switch off. Turn the switch inside the furnace on. The switch in the gas system needs to be turned on as well. The switch will need electricity.
There is a power switch near the furnace, and that needs to be on too. The ductwork of the furnace can be a problem, and it may have gaps in them. The gaps won’t let the furnace ignite, so you need to turn to close the gaps in the sections. Duct tape may be helpful in closing the gaps between them. A metal tape is better for closing the gaps in the sections.
The last word
If you have a furnace that doesn’t light up even when the pilot next to it is on, then check the distance between the pilot and the furnace. The flame should touch the furnace. Make sure the furnace has enough gas to light up, just like the pilot. Get a professional. Thanks for reading!
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