The majority of gas furnaces are easier to operate than oil burners, and natural gas as well as propane burn more cleanly than fuel oil. In reality, issues with gas furnaces are frequently related to the thermocouple, your pilot light, or an electrical system component.
Although gas heaters and furnaces are equipped with shutoffs to stop gas leaks, they are not foolproof. Never switch on or off any lights in your home if you smell gas and stay away from the gas supply to the furnace.
Leave the door open as you leave the house, and phone the fire department or the gas company right away to report a leak. Do not go back inside your house if there is any threat of a gas leak.
The pilot light component is covered by a plug-type door on certain propane furnaces and heaters. Pull the door off from the furnace housing to access the pilot burner.
The assembly at the exterior of the furnace typically houses the thermocouple, reset buttons, propane valves, and pilot light controls. The main chamber (plenum) or main ductwork junction on the furnace’s top housing is where the furnace’s limit switch is situated.
What You will Need to Light a Pilot Light in a Furnace
To inspect the pilot light, you need have the following equipment available:
- Matches
- A thin wire
A gas furnace’s pilot light may go out due to drafts. Follow the manufacturer’s directions precisely to relight the pilot; they are often attached to the furnace. In the absence of specific instructions, adhere to the basic process as follows:
- Locate the pilot light assembly. A gas valve featuring on, off, as well as pilot modes is frequently included.
- Set the valve to the off position, then wait three minutes.
- Set the valve to the pilot position.
- While pressing the reset button on the pilot control panel, hold a lit match to the pilot aperture.
- Press this button until the pilot flame is bright, then set the valve to the on position.
Pilot flame not staying lit? It could be a possible plugged opening. Turn off the gas valve and use a fine wire to clean the aperture. After repeated efforts, if it still will not remain lighted, you could have a bad thermocouple. Call a qualified heating repair from Hilliard, OH service provider if the pilot flame still will not remain lit.
Some furnaces lack a pilot light and instead use an electronic system that ignites the gas. Instead, the burners are heated and ignited by an electric element. Call a qualified service technician if this electronic ignition system is not working properly. A safety device called a thermocouple might be broken if the pilot lamp would not stay lit.
Thermocouple Replacement Procedure
The thermocouple is a part of a gas furnace that is situated close to the burner for the pilot lamp. It is a safety feature that turns off the gas if the electric igniter or pilot light malfunctions. It may be necessary to modify or replace the thermocouple if the pilot lamp will not remain lit.
You must use a wrench to tighten the temperature sensor (https://eng.libretexts.org/Bookshelves/Industrial_and_Systems_Engineering/Chemical_Process_Dynamics_and_Controls_Sensors_and_Actuators_Temperature_Sensors) nut in order to adjust the thermocouple. Be careful not to tighten the nut too much; just a little bit will do. Then attempt to ignite the pilot. Replace the thermocouple in question with an alternate one of the same types if the pilot will not remain lit.
This is how a thermocouple is changed
- Inside the threaded connection to the gas line, unscrew the connection nut and copper lead.
- Unscrew the bracket nut holding the thermocouple tube in position under the mounting bracket.
- Attach a fresh thermocouple to the hole that is inside of the bracket.
- Make sure the copper connection is down and the steel tube is high.
- Screw a bracket nut over a tube under a bracket.
- Where copper lead joins the gas line, push the connecting nut onto the threaded connector. Ensure a dry and clean connection.
- Screw the nut in firmly but not too tightly. The connecting nut and the bracket nut should only be somewhat tighter than if they had been hand-tightened.
On a gas furnace, the thermocouple is situated adjacent to the pilot light.
A safety management switch known as a limit switch is situated on the furnace directly below the plenum. Click here to learn more about limit switches. The limit switch turns off the burner if the plenum heats up too much. When the temperature reaches a particular point after the burner is turned off, it also turns off the blower.
If the fan runs continually, either the limit controller switch has to be adjusted, or the blower controller on the thermostat itself has been turned to the on position. First, check the thermostat. Change the blower control from on to auto if it is now set to on; if it is already set to auto, the limit switch has to be adjusted.
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